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COVID-19

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COVID-19

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COVID-19
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Vaccine Products Contraindications and Precautions
COVID-19 Vaccines for Children under 12 Years Vaccine Safety
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This page was last updated on August 3, 2022. Guidance from CDC about COVID-19 vaccines may be updated frequently. For questions about guidance issued after this date, readers are referred directly to the Centers for Disease Control and Prevention (CDC) Use of COVID-19 Vaccines in the United States Interim Clinical Considerations: www.cdc.gov/vaccines/covid-19/clinical-considerations/covid-19-vaccines-us.html.

For a comprehensive collection of COVID-19 tools and resources, visit Immunize.org’s Vaccines: COVID-19 main page: www.immunize.org/covid-19. For alerts about new Immunize.org or CDC COVID-19 resources, subscribe to our weekly newsletter, IZ Express.
Disease Issues
What is COVID-19?
COVID-19 is the name given to the disease caused by infection with the SARS-CoV-2 coronavirus. This virus was first detected as a cause of human illness in late 2019 in Wuhan, China, and triggered a global pandemic that began in 2020. The virus is thought to spread mainly from person to person through respiratory droplets produced when an infected person coughs, sneezes, or talks. These droplets can land in the mouths or noses of people who are nearby or possibly be inhaled into the lungs. Some people who are infected have no symptoms of illness, while the severity of symptomatic illness ranges from mild to life-threatening. Older adults and people of any age with underlying medical conditions are at higher risk for severe illness.
The incubation period after exposure ranges from 2–14 days, with an average of about 5 days. People with COVID-19 are generally considered infectious up to 48 hours before symptom onset through 10 days after onset, though people with severe illness may be infectious longer. Symptoms may include fever or chills, cough, shortness of breath or difficulty breathing, fatigue, muscle or body aches, headache, new loss of taste or smell, sore throat, congestion or runny nose, nausea or vomiting, and diarrhea.
Where can I find answers to more clinical questions about COVID-19 disease, diagnosis, treatment and care of patients?
The CDC has assembled clinical questions and answers at this site: www.cdc.gov/coronavirus/2019-ncov/hcp/faq.html.
Vaccine Recommendations Back to top
Where can I find current COVID-19 vaccine recommendations?
The CDC's Advisory Committee on Immunization Practices (ACIP) has published recommendations for all COVID-19 vaccines that have received Emergency Use Authorization (EUA) or licensure from the federal Food and Drug Administration (FDA). ACIP and the CDC update vaccination recommendations frequently. Changes in CDC recommendations may be issued without an ACIP meeting or vote. All ACIP COVID-19 vaccine recommendations that have been published by CDC in MMWR can be accessed here: www.cdc.gov/vaccines/hcp/acip-recs/vacc-specific/covid-19.html.
In addition to published ACIP recommendations for the use of these vaccines, CDC maintains a website with critical interim clinical considerations for vaccination of eligible recipients: www.cdc.gov/vaccines/covid-19/clinical-considerations/covid-19-vaccines-us.html. This site is updated within days of any change to CDC recommendations.
Has CDC developed a frequently asked question (FAQ) page for COVID-19 vaccines?
Yes. CDC has an FAQ page about COVID-19 vaccines specifically for healthcare providers: www.cdc.gov/vaccines/covid-19/hcp/faq.html. This page includes CDC answers related to vaccination programs, EUA, administration, storage and handling, and safety and efficacy.
Who is recommended to receive COVID-19 vaccines?
All people age 6 months and older in the United States are recommended to receive an age-appropriate COVID-19 vaccination. Details of CDC’s recommendations for each product are available here: www.cdc.gov/vaccines/covid-19/clinical-considerations/interim-considerations-us.html#recommendations.
Who is eligible to receive a booster dose of a COVID-19 vaccine?
ACIP recommends that all people age 5 years and older who have completed primary vaccination against COVID-19 with an mRNA COVID-19 vaccine or the Janssen COVID-19 Vaccine (Johnson & Johnson) should receive at least one age-appropriate COVID-19 vaccine booster dose at the appropriate interval. Novavax COVID-19 Vaccine primary series recipients are not yet recommended to receive a booster dose and the Novavax vaccine is not yet authorized for use as a booster dose for individuals who received a different primary series vaccine.
The mRNA COVID-19 vaccines should be used when booster doses are indicated in almost all circumstances. However, offering the Janssen COVID-19 Vaccine to an individual age 18 years or older under the limited terms of its current FDA emergency use authorization (www.fda.gov/emergency-preparedness-and-response/coronavirus-disease-2019-covid-19/janssen-covid-19-vaccine) is preferable to not providing any COVID-19 vaccine.
Please refer to CDC’s At-A-Glance COVID-19 Vaccination Schedules document for the most current recommended booster dose schedules by age and product type: www.cdc.gov/vaccines/covid-19/downloads/COVID-19-vacc-schedule-at-a-glance-508.pdf.
For further details, please review the recommendations information available through CDC’s web page, “Use of COVID-19 Vaccines in the United States” at: www.cdc.gov/vaccines/covid-19/clinical-considerations/covid-19-vaccines-us.html.
I know that the authorized and recommended use of Janssen COVID-19 is now limited to certain individuals. Who may receive the Janssen COVID-19 Vaccine?
The ACIP voted in December 2021 to prefer the use of mRNA vaccines for the prevention of COVID-19 because the Janssen vaccine is associated with very rare, but serious, side effects: thrombosis with thrombocytopenia (TTS) and Guillain-Barré Syndrome (GBS). Cases of TTS have occurred among male and female adults of all ages, with the highest rate among women age 30 to 49 (about 1 case per 100,000 doses). Approximately 15% of reported TTS cases have been fatal. See the section on vaccine safety for additional information. The mRNA vaccines have not been associated with these side effects.
In light of these facts and the widespread availability of mRNA vaccines, in May 2022, FDA limited its EUA for the Janssen COVID-19 Vaccine. The EUA now states that the Janssen vaccine is available to prevent COVID-19 in individuals 18 years of age and older for whom other FDA-authorized or approved COVID-19 vaccines are not accessible or are not clinically appropriate, and individuals 18 years of age and older who elect to receive it because they would otherwise not receive a COVID-19 vaccine. For these individuals, the Janssen COVID-19 vaccine is authorized as:
a single primary vaccination dose
a single booster dose at least two months after completing primary vaccination with the vaccine
  a single booster dose following completion of primary vaccination with a different available COVID-19 vaccine. The dosing interval for the booster dose is the same as that authorized for a booster dose of the vaccine used for primary vaccination.
All people who elect to receive a Janssen COVID-19 vaccine booster should be informed about the risk and symptoms of TTS that could occur after vaccination (typically within 2 weeks after receipt) and the need to seek immediate medical care should such symptoms develop at any time.
Should people who have had COVID-19 illness be vaccinated?
Yes. Vaccination should be offered to individuals regardless of history of prior SARS-CoV-2 infection. People who are unvaccinated have a higher risk of reinfection than those who are fully vaccinated following natural infection. CDC has summarized the available data on vaccine-induced immunity and disease-induced immunity here: www.cdc.gov/coronavirus/2019-ncov/science/science-briefs/vaccine-induced-immunity.html.
Viral testing to assess for current SARS-CoV-2 infection or serologic testing to assess for prior infection for the purposes of vaccine decision-making is not recommended. However, as with all vaccines, vaccination should be deferred until after recovery from moderate to severe illness. In addition, to minimize the risk of exposing others to SARS-CoV-2 virus, vaccination of a person diagnosed with COVID-19 generally should be deferred until criteria have been met for individuals with COVID-19 illness to discontinue isolation.
Although waiting to vaccinate after infection is not necessary, people who recently had SARS-CoV-2 infection may consider delaying a primary series dose or their first or second COVID-19 vaccine booster dose by 3 months from symptom onset or positive test (if infection was asymptomatic). According to CDC, increasing the time between infection and vaccination may result in an improved immune response to vaccination. At this time, there is evidence of a low risk of reinfection in the weeks to months following infection. A recipient's individual risks for severe disease and current COVID-19 conditions in the community should be taken into account when deciding whether to delay vaccination up to 3 months after infection.
What is the difference between an "additional primary dose" of COVID-19 vaccine recommended for an immunocompromised person and a "booster dose"?
CDC defines an “additional primary dose” as a subsequent dose of vaccine administered to people who are less likely to develop a protective immune response after initial vaccination. People age 6 months or older who are moderately or severely immunocompromised should receive an additional primary dose of mRNA vaccine 4 weeks after the routinely recommended primary series, with two exceptions: (1) Novavax COVID-19 Vaccine 2-dose primary series recipients are not recommended to receive an additional dose at this time, and (2) those age 6 months through 4 years who receive the routine 3-dose Pfizer-BioNTech primary series are not recommended to receive an additional (fourth) primary series dose.
CDC defines a “booster dose” as a subsequent dose of vaccine administered to enhance or restore protection which might have declined over time after primary series vaccination.
A "homologous booster dose” simply means that the same vaccine product used for the booster dose was administered for the primary series.
A “heterologous booster dose,” sometimes referred to as a mix-and-match booster, is a vaccine product used for the booster dose that differs from the product administered for the primary series.
How does CDC define being "up to date" on COVID-19 vaccination?
CDC has used the term "fully vaccinated" to refer to people who have completed a primary COVID-19 vaccine series. CDC currently uses the term "up to date" (UTD) to refer to a person who has received all recommended doses in their primary vaccine series, and all booster doses recommended for them, when eligible.
As of May 20, 2022, immunocompromised people age 12 years or older and all people age 50 years or older should receive a second booster dose of either Pfizer-BioNTech COVID-19 Vaccine or Moderna COVID-19 Vaccine at least 4 months after their first booster dose to be considered up to date.
People age 18 through 49 years who received a Janssen COVID-19 Vaccine (Johnson & Johnson) for both their primary and booster dose may get a second booster dose of an mRNA COVID-19 vaccine, but the second booster dose is not required for these individuals to be considered up to date.
Vaccine Products Back to top
What is an Emergency Use Authorization (EUA)?
Under section 564 of the Federal Food, Drug, and Cosmetic Act (FD&C Act), the FDA Commissioner may allow unapproved medical products or unapproved uses of approved medical products to be used in an emergency to diagnose, treat, or prevent serious or life-threatening diseases or conditions caused by chemical, biological, radiological or nuclear threat agents when there are no adequate, approved, and available alternatives. Vaccines that receive an EUA may later be fully licensed by the FDA.
Which vaccines are currently licensed by the FDA?
On August 23, 2021, FDA approved the 2-dose primary series of the adolescent/adult formulation of Pfizer-BioNTech COVID-19 Vaccine for individuals age 16 years and older. In July 2022, the FDA expanded this license to include age 12 years and older. The brand name of this product is Comirnaty.
On January 31, 2022, FDA approved the 2-dose primary series of Moderna COVID-19 Vaccine for individuals age 18 years and older. The brand name of this product is Spikevax.
What does FDA's approval of the biologics licensure application (BLA) for Comirnaty, the Pfizer-BioNTech COVID-19 Vaccine, mean for my clinic?
The primary series of the adolescent/adult formulation of Pfizer-BioNTech COVID-19 Vaccine (trade name Comirnaty) is fully licensed and approved by the FDA for individuals age 12 years and older. In late 2021, FDA approved a manufacturing change for Comirnaty to use a different buffer to improve the stability of the vaccine; Comirnaty made with this buffer does not require dilution. It is packaged with a gray cap and gray trim around its label. As the existing supplies of the original purple cap (dilute before use) Comirnaty are replaced by the newer gray cap (do not dilute) formulation through 2022, both formulations will be available. They are considered the same vaccine; however, vaccinators must be careful to ensure that they are stored and handled correctly because their storage and handling requirements are different.
Comirnaty remains authorized for emergency use for administration of an additional primary series dose and as a first or second booster dose in immunocompromised people ages 12 and older, and for administration as a first booster dose to all people ages 12 and older and second booster dose under specified conditions. CDC has issued emergency use instructions (EUI) for the use of this vaccine in people age 12 or older whose primary series included a COVID-19 vaccine not authorized or approved by the FDA, given either as part of a clinical trial or as partial or complete routine vaccination in another country. The EUI also addresses revaccination of people who have received hematopoietic cell transplant (HCT) therapy or CAR-T-cell therapy. EUI resources are available here: www.cdc.gov/vaccines/covid-19/eui/index.html.
For simplicity, the Ask the Experts COVID-19 section refers to Comirnaty as Pfizer-BioNTech COVID-19 Vaccine, referring, when necessary, to its two formulations as the purple cap (dilute before use) or gray cap (do not dilute) formulations.
The FDA Fact Sheet reflects the trade name and combines information for individuals receiving the adolescent/adult formulation in accordance with its licensed indication with information for those receiving the product under the terms of its emergency use authorization (EUA).
There is no Vaccine Information Statement (VIS) for COVID-19 vaccines. All clinics providing the adolescent/adult Pfizer-BioNTech COVID-19 Vaccine for a recipient age 12 years or older should use the most current EUA Fact Sheet that corresponds with the correct formulation. The current EUA Fact Sheets for healthcare providers and for recipients and caregivers in English and additional languages are available from FDA at this web page: www.fda.gov/emergency-preparedness-and-response/coronavirus-disease-2019-covid-19/Comirnaty-and-pfizer-biontech-covid-19-vaccine.
What are the differences in the purple cap (dilute before use), gray cap (do not dilute), and orange cap (dilute before use) formulations of Pfizer-BioNTech COVID-19 Vaccine?
There are four different preparations of Pfizer-BioNTech COVID-19 vaccine, each distinguished by its cap color and matching vial label trim. The maroon cap is for recipients ages 6 months through 4 years, the orange cap is for recipients 5 through 11 years, and either purple or gray cap may be given to recipients age 12 years or older. CDC has summarized the differences among each Pfizer-BioNTech formulation, including storage, preparation, and schedules, in a PDF document free to download and share or print: www.cdc.gov/vaccines/covid-19/info-by-product/pfizer/downloads/vaccine-at-a-glance.pdf.
There is no Vaccine Information Statement (VIS) for recipients of COVID-19 vaccines. In place of the VIS, recipients should be given the FDA’s EUA Fact Sheet for Recipients and Caregivers prepared for the specific formulation. All EUA Fact Sheets for licensed and authorized Pfizer-BioNTech formulations are posted by the FDA on this website: www.fda.gov/emergency-preparedness-and-response/coronavirus-disease-2019-covid-19/comirnaty-and-pfizer-biontech-covid-19-vaccine.
We don’t have a VIS for COVID-19 vaccines. What information am I supposed to give patients in writing?
For each COVID-19 vaccine authorized under an Emergency Use Authorization (EUA), the Food and Drug Administration (FDA) requires that vaccine recipients or their caregivers are provided with certain vaccine-specific EUA information to help make an informed decision about vaccination. This is accomplished by providing an EUA Fact Sheet for Recipients and Caregivers. The Fact Sheet is similar in purpose and content to vaccine information statements (VISs) for licensed vaccines but differs in that the EUA Fact Sheet is specific to each authorized COVID-19 vaccine, is developed by the manufacturer of the vaccine, and is authorized by the FDA. There is a separate EUA Fact Sheet for each formulation of a vaccine. For example, there are different Fact Sheets for each of the Pfizer-BioNTech COVID-19 Vaccine formulations (maroon cap, orange cap, gray cap, and purple cap).
CDC has issued Emergency Use Instructions (EUI) for the use of the FDA-licensed formulations of Pfizer-BioNTech COVID-19 Vaccine (Comirnaty), or Moderna COVID-19 Vaccine (Spikevax) for certain people vaccinated with vaccines not authorized or approved by the FDA, whether given outside the United States or as part of a clinical trial. The EUI also addresses revaccination of people who have received hematopoietic cell transplant (HCT) or CAR-T-cell therapy. These instructions may differ from the FDA-approved labeling (the package insert). People vaccinated in accordance with these emergency use instructions should be given an EUI Fact Sheet at the time of vaccination. Information about CDC EUI and links to these fact sheets for providers and recipients or caregivers are available here: www.cdc.gov/vaccines/covid-19/eui/index.html.
Until there is a VIS for COVID-19 vaccine, FDA has issued revised fact sheets for Comirnaty and Spikevax that cover both their limited licensed indications as a primary series for people age 12 and older (Comirnaty) or age 18 and older (Spikevax) and their broader emergency use authorizations. Once a COVID-19 VIS is issued, the VIS and all available translations will be posted here: https://immunize.org/vis/.
Below are links to each Fact Sheet for Recipients and Caregivers by age group and product type:
1. Combined Fact Sheet for Recipients and Caregivers about Comirnaty and Pfizer-BioNTech COVID-19 Vaccine (age 12 years and older, purple cap, dilute before use): www.fda.gov/media/153716/download
2. Combined Fact Sheet for Recipients and Caregivers about Comirnaty and Pfizer-BioNTech COVID-19 Vaccine (age 12 years and older, gray cap, do not dilute): www.fda.gov/media/153715/download
3. Pfizer COVID-19 Vaccine EUA Fact Sheet for Recipients and Caregivers (age 5 through 11 years, orange cap): www.fda.gov/media/153717/download
4. Pfizer COVID-19 Vaccine EUA Fact Sheet for Recipients and Caregivers (age 6 months through 4 years, maroon cap): www.fda.gov/media/159313/download
5. Combined Fact Sheet for Recipients and Caregivers about Spikevax and Moderna COVID-19 Vaccine (age 12 years and older): www.fda.gov/media/144638/download
6. Moderna COVID-19 Fact Sheet for Recipients and Caregivers (age 6 years through 11 years): www.fda.gov/media/159310/download
7. Moderna COVID-19 Fact Sheet for Recipients and Caregivers (age 6 months through 5 years, blue cap, magenta [hot pink] vial label border): www.fda.gov/media/159309/download
8. Janssen COVID-19 Vaccine EUA Fact Sheet for Recipients and Caregivers (age 18 years and older): www.fda.gov/media/146305/download.
9. Novavax COVID-19 Vaccine, Adjuvanted EUA Fact Sheet for Recipients and Caregivers (age 18 years and older): www.fda.gov/media/159898/download
What are the differences among the presentations of Moderna COVID-19 Vaccine?
Moderna COVID-19 Vaccine has 3 presentations for different age groups or uses, each identified by its vial cap and label combination. The vial with a blue cap and magenta (hot pink) bordered label contains 10 doses (25 mcg per 0.25 mL dose): it is for children age 6 months through 5 years. The vial with a blue cap and purple-bordered label contains 5 doses (50 mcg per 0.5 mL dose): it is for primary series doses in children age 6 through 11 years or for booster doses in adults age 18 years or older. The vial with a red cap and blue-bordered label contains 10 doses (100 mcg per 0.5 mL dose) for use as primary series doses in adults age 18 years or older; this vial also may be used to deliver a 50-mcg dose in 0.25 mL when needed as a booster dose in an adult.
CDC has summarized the differences among each Moderna presentation, including storage, preparation, and schedules, in a PDF document free to download and share or print: www.cdc.gov/vaccines/covid-19/info-by-product/moderna/downloads/vaccine-at-a-glance.pdf.
Vaccinators who stock multiple presentations should check three times to confirm that they are administering the proper product with the proper dose and dose volume for each patient.
 
What are mRNA vaccines?
Both the Pfizer-BioNTech COVID-19 Vaccine and the Moderna COVID-19 (mRNA-1273) Vaccine are lipid nanoparticle-formulated, nucleoside-modified mRNA vaccines encoding the prefusion spike glycoprotein of SARS-CoV-2, the virus that causes coronavirus disease 2019. Both mRNA vaccines have been associated with a rare occurrence of myocarditis and/or pericarditis; cases have occurred predominantly among males ages 12 through 39: see the vaccine safety section for additional information. Visit this CDC website for more details about how mRNA vaccines work: www.cdc.gov/coronavirus/2019-ncov/vaccines/different-vaccines/mrna.html.
How well did the mRNA COVID-19 vaccines work in the clinical trials?
The FDA EUA was issued based upon the short-term effectiveness of these vaccines at preventing symptomatic illness with COVID-19. The Pfizer-BioNTech vaccine (Comirnaty) was licensed by FDA with a reported vaccine efficacy of 91.1% against symptomatic disease among recipients age 16 years or older up to 6 months after dose 2. Both Moderna and Pfizer-BioNTech vaccines maintain approximately 90% protection against severe disease for at least 6 months after vaccination. Early observational studies of short-term effectiveness in a variety of populations were consistent with the clinical trial results. Vaccine effectiveness wanes over time and can be improved by the administration of booster doses as recommended by CDC. Vaccine effectiveness may be different for new variants of COVID-19.
Please describe the Janssen COVID-19 Vaccine (Johnson & Johnson).
The Janssen vaccine is a recombinant, replication-incompetent (unable to reproduce) adenovirus serotype 26 (Ad26) vector vaccine, encoding the stabilized prefusion spike glycoprotein of SARS-CoV-2. On February 27, 2021, the FDA first issued an Emergency Use Authorization (EUA) for the Janssen COVID-19 (Ad.26.COV2.S) Vaccine (Johnson & Johnson). Due to the extremely rare risk of the serious complications of thrombosis with thrombocytopenia syndrome (TTS) or Guillain-Barre syndrome (GBS) following vaccination with this product, the Janssen COVID-19 Vaccine is currently authorized for use in individuals 18 years of age and older for whom other FDA-authorized or approved COVID-19 vaccines are not accessible or clinically appropriate, and for individuals 18 years of age and older who elect to receive the Janssen COVID-19 Vaccine because they would otherwise not receive a COVID-19 vaccine.
Primary vaccination of people who are not moderately or severely immunocompromised consists of a single dose of Janssen vaccine administered intramuscularly. A booster dose of any authorized or licensed COVID-19 vaccine is recommended for these recipients at least 2 months (8 weeks) following this single dose. If Janssen vaccine is administered for both the primary and first booster dose to a person age 18 through 49 years, a second booster dose of an mRNA vaccine may be considered at least 4 months after the first booster dose. Individuals age 50 years or older should receive a second booster dose of an mRNA vaccine administered at least 4 months after the first booster dose, regardless of the product used for the first booster dose.
People age 18 years or older with moderate to severe immunocompromise who receive a primary dose of Janssen vaccine should receive an additional primary dose of an mRNA vaccine at least 28 days after the Janssen vaccine. A booster dose of any authorized or licensed COVID-19 vaccine (preferably mRNA) is recommended at least 2 months after the additional primary dose. A second booster dose of an mRNA vaccine should be administered at least 4 months after the first booster dose to moderately or severely immunocompromised recipients.
How well did the Janssen COVID-19 Vaccine work in the clinical trials?
A large phase 3 trial was initiated in September 2020 and enrolled more than 43,000 individuals in multiple countries, including the United States, Brazil, and South Africa. Interim results demonstrated a 66% reduction in the risk of symptomatic COVID-19 beginning at least 14 days following vaccination; efficacy against severe disease was higher. The risk of hospitalization 14 days or more after vaccination was reduced by 93% compared to placebo recipients; no hospitalizations occurred among vaccine recipients 28 days or more after vaccination. No deaths related to COVID-19 infection occurred among vaccine recipients, while seven occurred among placebo recipients.
In the months following EUA, vaccine effectiveness against severe disease and hospitalization remained high against known variants, including the Delta variant, even as protection against milder illness appeared reduced. Receipt of a booster dose at least 2 months after the primary dose substantially increases neutralizing antibodies to levels consistent with a high degree of protection against symptomatic infection. Due to the occurrence of very rare but serious side effects, mRNA vaccines (which are not associated with these side effects) are preferred over Janssen vaccine for primary and booster vaccination of eligible recipients in the United States. Vaccine effectiveness may be different for different variants of COVID-19.
What is the Novavax COVID-19 Vaccine?
Novavax COVID-19 Vaccine, Adjuvanted contains the SARS-CoV-2 spike protein and Matrix-M adjuvant. The saponin-based adjuvant is made from extracts of the bark of the Soapbark tree native to Chile. It is added to enhance the immune response of the vaccine recipient. The spike protein is produced in insect cells. It was authorized in July 2022 for emergency use in adults age 18 years or older as a two-dose primary series, with the doses given at least 3 weeks apart. It is not currently authorized for use as a booster dose in people who have already received a primary series.
The initial ACIP recommendations for use of Novavax COVID-19 Vaccine are available here: www.cdc.gov/mmwr/volumes/71/wr/mm7131a2.htm?s_cid=mm7131a2_w.
How well does the Novavax COVID-19 Vaccine work?
The effectiveness of Novavax COVID-19 Vaccine against currently circulating variants of SARS-CoV-2 is not precisely known. Clinical trials of this vaccine were conducted against earlier variants no longer in circulation; however, the vaccine showed very good effectiveness against moderate to severe disease during clinical trials. Testing conducted on antibodies in the serum of Novavax vaccine recipients suggests that vaccination provides substantial protection against severe disease and death caused by currently circulating variants, consistent with other available COVID-19 vaccines.
How well do COVID-19 vaccines work to prevent asymptomatic infection with SARS-CoV-2? Based on that, what can people do when they are up to date on their COVID-19 vaccinations?
Some evidence suggests that people who are up to date (UTD) with COVID-19 vaccination are less likely than the unvaccinated to have asymptomatic infection or transmit SARS-CoV-2 to others; however, the degree of protection varies depending on the variant of the virus in circulation and declines over time. CDC guidelines for UTD individuals are updated as new data become available: www.cdc.gov/coronavirus/2019-ncov/vaccines/fully-vaccinated-guidance.html.
 
Where can I obtain detailed information about the COVID-19 vaccines?
CDC has developed a "one-stop" product-specific webpage for each COVID-19 vaccine with all of the important details that immunization providers need to know.
Pfizer-BioNTech COVID-19 Vaccine (all formulations): www.cdc.gov/vaccines/covid-19/info-by-product/pfizer/index.html.
Moderna COVID-19 Vaccine: www.cdc.gov/vaccines/covid-19/info-by-product/moderna/index.html.
  Janssen COVID-19 Vaccine: www.cdc.gov/vaccines/covid-19/info-by-product/janssen/index.html.
  Novavax COVID-19 Vaccine: www.cdc.gov/vaccines/covid-19/info-by-product/novavax/index.html.
In addition to CDC, each company has a detailed EUA Fact Sheet for healthcare providers administering vaccine.
1. Pfizer-BioNTech COVID-19 Vaccine (for age 12 years and older, purple cap): www.fda.gov/media/153713/download
2. Pfizer-BioNTech COVID-19 Vaccine (for age 12 years and older, gray cap): www.fda.gov/media/153715/download
3. Pfizer-BioNTech COVID-19 Vaccine (for age 5 through 11 years, orange cap): www.fda.gov/media/153714/download
4. Pfizer-BioNTech COVID-19 Vaccine (for age 6 months through 4 years, maroon cap): www.fda.gov/media/159312/download
5. Moderna COVID-19 Vaccine (red cap, light blue label border, primary series age 12 years and older, or booster dose, ages 18 years and older): www.fda.gov/media/157233/download
6. Moderna COVID-19 Vaccine (dark blue cap, purple label border, booster dose for age 18 years and older): www.fda.gov/media/157232/download
7. Moderna COVID-19 Vaccine (dark blue cap, purple label border, primary series dose for age 6 years through 11 years): www.fda.gov/media/159308/download
8. Moderna COVID-19 Vaccine (blue cap, magenta [hot pink] label border, primary series dose age 6 months through 5 years): www.fda.gov/media/159307/download
9. Novavax COVID-19 Vaccine (primary series, age 18 years and older): www.fda.gov/media/159897/download
10. Janssen COVID-19 Vaccine (primary series or first booster, age 18 years and older): www.fda.gov/media/146304/download
COVID-19 Vaccines for Children under 12 Years Back to top
What are the recommendations for COVID-19 vaccination of children younger than age 12 years?
All children age 6 months and older should be vaccinated against COVID-19. Both mRNA vaccines (Pfizer-BioNTech and Moderna) are authorized for use in children down to age 6 months. The number of doses and recommended formulations vary by age and by immunocompromised health status.
Refer to the CDC’s current recommended immunization schedule for age groups beginning at age 6 months in this PDF document: www.cdc.gov/vaccines/covid-19/downloads/COVID-19-immunization-schedule-ages-6months-older.pdf.
Our clinic does not stock the orange cap formulation of Pfizer-BioNTech COVID-19 Vaccine for children age 5 through 11 years. Could we draw up a 10 microgram (mcg) dose out of the purple cap adolescent/adult formulation to vaccinate these children?
No. Children 5 through 11 years should only be vaccinated with a 10-mcg dose (0.2 mL) of the orange cap (dilute before use) Pfizer-BioNTech formulation specifically authorized for ages 5 through 11 years, except as permitted by the FDA when a child is within 21 days of their 12th birthday, as described in the next question.
A dose of the purple cap (dilute before use) or gray cap (do not dilute) formulation for adolescents and adults delivers 30 mcg in a 0.3 mL volume. Ten mcg (the dose for a child 5 through 11 years) would be just 0.1 mL, a volume too small to reliably deliver the correct amount intramuscularly. It is never acceptable to alter the dilution volume or to dilute a formulation that should not be diluted in order to create a larger dose volume.
My patient turns 12 years old later this month. Should they get the lower-dose Moderna or Pfizer-BioNTech vaccine formulation approved for age 11 years now or wait and get the higher dose products authorized at age 12?
Do not wait. The simple rule is that children should receive a vaccine dosage and formulation authorized specifically for their age on the day of vaccination with each dose. However, the FDA authorization provides flexibility for product selection when managing children who transition from a younger to an older age group during the primary series. CDC has prepared reference documents outlining recommended and acceptable options for each mRNA vaccine when children transition from a younger to an older age group while receiving the primary series.
Moderna: www.cdc.gov/vaccines/covid-19/downloads/Moderna-Child-Age-Transition-508.pdf.
Pfizer-BioNTech: www.cdc.gov/vaccines/covid-19/downloads/Pfizer-Child-Age-Transition-508.pdf.
What do we know about the orange cap Pfizer-BioNTech COVID-19 Vaccine effectiveness and side effects in children ages 5 through 11 years?
Preliminary clinical trial results (initial enrollment of 2,268 children) showed that two 10-microgram (mcg) doses of orange cap (dilute before use) Pfizer-BioNTech COVID-19 Vaccine formulation for age 5 through 11 years, administered 21 days apart, reduced the risk of symptomatic COVID-19 illness by 90.9 percent for at least two months. The immune response to this dose in this age group was at least as strong as the immune response to two 30 mcg doses of the purple cap Pfizer-BioNTech COVID-19 Vaccine formulation among recipients age 16 through 25 years.
During the 7 days following vaccination, almost 9 in 10 children reported a local reaction, primarily pain at the injection site, and 2 of 3 reported a systemic reaction (most commonly fatigue or headache). The vast majority of reactions were mild or moderate and resolved within 1?2 days; reactions were milder than those reported by young adult recipients of the purple cap formulation. Systemic reactions were more likely to be reported following dose 2. No serious adverse events related to vaccination were observed in the clinical trial.
What do we know about the safety and effectiveness of Moderna and Pfizer-BioNTech mRNA COVID-19 vaccines in the youngest children?
Variants in circulation at the time of the clinical trials in young children (6 months through 4 years for Pfizer-BioNTech and 6 months through 5 years for Moderna) are no longer in circulation, so it is not possible to state with certainty how effective these vaccines are in young children against currently circulating variants. However, the recommended schedules of both Moderna and Pfizer-BioNTech vaccines in children as young as 6 months produce an immune response consistent with the immune response seen in older age groups where effectiveness against symptomatic infection, and particularly effectiveness against severe COVID-19, has been demonstrated.
Both vaccines have been demonstrated to be safe, with side effects typical of those in older age groups. The most common local reaction in this age group is pain at the injection site; the most common systemic symptom in older children was fatigue and in younger children (6 through 23 months) irritability/crying and sleepiness were most common. Fever may occur after either vaccination. Febrile seizures can occur in infants and young children ages 6 months through 5 years as a result of any condition that causes a fever (most common with high fevers). Febrile seizures are uncommon after vaccination. Febrile seizures were rare after mRNA COVID-19 vaccine clinical trials in this age group, but CDC is monitoring for this adverse event following vaccination in infants and young children.
No cases of myocarditis were reported during the clinical trials for either vaccine; however, the clinical trials were not large enough to detect a very small risk, and CDC is monitoring for this adverse event among recipients. Lengthening the interval between doses 1 and 2 may substantially reduce the risk of myocarditis. CDC recommends that the interval between dose 1 and 2 may be up to 8 weeks for all children and adults through age 64, unless rapid protection is a priority because the recipient has either a high risk of severe disease or a high risk of exposure.
COVID-19 Vaccines for Adolescents and Adults Back to top
What COVID-19 vaccine options are available for adolescents and adults ages 12 years and older?
The purple cap (dilute before use) and gray cap (do not dilute) formulations of the Pfizer-BioNTech COVID-19 Vaccine are licensed (with the brand name Comirnaty) as a primary series for age 12 years and older and booster doses are authorized for emergency use in this age group.
Moderna (Spikevax) is licensed for the primary series in ages 18 years and older and is authorized for emergency use in people age 12 years and older.
Novavax COVID-19 Vaccine is authorized for emergency use as a primary series in adults age 18 years and older.
Janssen COVID-19 vaccines are authorized for emergency use in certain people age 18 years and older for whom vaccination with an alternative vaccine is not feasible.
FDA authorization of additional vaccine products or authorization of current products for expanded age groups could occur if sufficient data are generated and submitted in an application to FDA.
Why has CDC provided the option to increase the interval between dose 1 and dose 2 of mRNA and Novavax COVID-19 vaccines up to 8 weeks?
CDC recommends the option of an 8-week interval between doses 1 and 2 of mRNA and Novavax vaccines for most people. Large observational studies in other countries have provided evidence that an 8-week interval may result in higher antibody levels and a reduced risk of vaccine-associated myocarditis, which is most likely to occur after dose 2. For this reason, an 8-week interval of an age-appropriate product may be optimal for some people age 6 months through 64 years, especially males age 12 through 39 years who are at the greatest risk of myocarditis after dose 2.
Shorter intervals (3 weeks for Pfizer-BioNTech and Novavax; 4 weeks for Moderna) protect the recipient more quickly. Therefore, a shorter interval remains the recommended interval for the following groups:
All people who are moderately to severely immunocompromised
All adults age 65 years and older
  Others who need rapid protection due to increased risk of exposure or risk of severe disease
What is the difference between the gray cap and purple cap formulations of Pfizer-BioNTech COVID-19 Vaccine?
The purple cap (dilute before use) and gray cap (do not dilute) are the same vaccine (with each dose containing 30 mcg of mRNA), formulated with different buffers. As a result, they have the same schedule and dosage, but very different storage and handling requirements. In late 2021, FDA approved a manufacturing change for Comirnaty (adolescent/adult Pfizer-BioNTech COVID-19 Vaccine) to include a formulation that uses a different buffer. The new formulation (gray cap) contains Tris buffer, a commonly used buffer in other FDA-approved vaccines and biologics. This new formulation is more stable at refrigerated temperatures for longer periods of time. The gray cap (do not dilute) Pfizer-BioNTech COVID-19 Vaccine is used on the same schedule and for the same ages as the purple cap (dilute before use) vaccine (ages 12 years and older). The gray cap may be stored in an ultra-low temperature (ULT) freezer for up to 12 months and in the refrigerator up to 10 weeks. It should never be stored in an ordinary freezer, nor should it be refrozen after thawing.
Distribution of the purple cap (dilute before use) formulation within the United States ended on December 23, 2021. This product may be available for use until all supplies are used or expire by sometime during the second half of 2022. It may be stored in a ULT freezer for up to 12 months, in a standard freezer for up to 2 weeks, and in a refrigerator for up to one month (31 days). It should never be refrozen after thawing.
For a table showing the differences among the four Pfizer-BioNTech COVID-19 Vaccine formulations, refer to this document produced by Pfizer-BioNTech: www.cvdvaccine-us.com/images/pdf/Vaccine-Formulation-Presentation-Guide.pdf.
What do we know about the Pfizer-BioNTech COVID-19 Vaccine effectiveness and side effects in children and young teens in the 12- to 15-year-old age group?
Clinical trial results demonstrated that the immune response of young adolescents in this age group to two 30 mcg doses separated by 21 days was similar to that observed in people age 16–25 years. No symptomatic cases of COVID-19 were detected among fully vaccinated people age 12–15 years. Among vaccine recipients age 12–15 years, side effects during the 7 days after vaccination were commonly reported (90.9% of vaccine recipients reported a local reaction and 90.7% reported a systemic reaction). Most reactions were mild to moderate. Pain at the injection site was the most common local reaction. One in 10 reported a side effect that interfered with daily activities. Side effects usually resolved after 1–2 days. Systemic side effects (e.g., fever, fatigue, headache, muscle pain) were more commonly reported after the second dose than after the first dose. No specific safety concerns were identified among adolescent vaccine recipients.
Special Populations Back to top
Are COVID-19 vaccines safe during pregnancy?
A growing body of evidence on COVID-19 vaccination during pregnancy has not indicated any safety or effectiveness concerns for vaccination at any stage of pregnancy; the benefits of vaccination clearly outweigh any known or potential risks of COVID-19 vaccination during pregnancy. The currently authorized or licensed COVID-19 vaccines are non-replicating vaccines and cannot cause infection in either the mother or the fetus. No evidence exists of risk to the fetus from vaccinating pregnant people with non-replicating vaccines in general. Just like the general population, COVID-19 vaccines other than Janssen are preferred during pregnancy; Janssen vaccine may be considered when mRNA vaccination is not feasible.
No safety concerns were found in animal developmental and reproductive toxicity studies of animals that received Pfizer-BioNTech, Moderna, or Janssen vaccines. Reassuring early safety data on mRNA COVID-19 vaccines administered to people during pregnancy have been published by CDC. Data from the Vaccine Adverse Events Reporting System (VAERS), the v-safe surveillance system, and the v-safe pregnancy registry have not signaled any safety concerns for pregnant people who were vaccinated or their infants. The vaccine manufacturers are following the pregnancy outcomes of people in the clinical trials who became pregnant. Additional studies in pregnant people are ongoing in order to fully evaluate pregnancy and birth outcomes.
Pregnant individuals should be vaccinated and are encouraged to enroll in CDC’s voluntary COVID-19 vaccine safety surveillance system, v-safe. The v-safe pregnancy registry follows outcomes among pregnant people who are vaccinated.
Can COVID-19 vaccination lead to fertility problems?
There is currently no evidence that any of the COVID-19 vaccines affect current or future fertility. In fact, there is currently no evidence that any vaccines cause fertility problems. Many individuals have become pregnant after receiving COVID-19 vaccine; ongoing long-term studies of pregnancy outcomes following vaccination are underway.
Are COVID-19 vaccines recommended during pregnancy?
Yes. COVID-19 vaccination is recommended for all people who are pregnant, lactating, trying to get pregnant now, or planning for future pregnancy. Pregnant people are at increased risk of severe complications and death from COVID-19 compared to non-pregnant people of the same age. Those who contract COVID-19 during pregnancy also have almost twice the risk of stillbirth compared to those who do not contract COVID-19 during pregnancy. Recent studies have shown that antibodies produced after COVID-19 vaccination during pregnancy are transferred to the newborn, and COVID-19 vaccination of people who are pregnant reduces the risk of COVID-19 hospitalization in infants younger than 6 months. Pregnant people may receive a booster dose during pregnancy, if eligible.
CDC, the American College of Obstetricians and Gynecologists (ACOG), and the Society for Maternal-Fetal Medicine (SMFM) all recommend vaccination of pregnant people at any stage of pregnancy.
For more details about COVID-19 vaccination during pregnancy, visit CDC’s webpage, “COVID-19 Vaccines while Pregnant or Breastfeeding”: www.cdc.gov/coronavirus/2019-ncov/vaccines/recommendations/pregnancy.html.
Are COVID-19 vaccines recommended if the recipient is breastfeeding?
Yes. COVID-19 vaccination is recommended for people who are lactating.
There are limited data on the safety of currently available COVID-19 vaccines on the breastfed infant or milk production/excretion. However, the currently available COVID-19 vaccines cannot cause infection in either the lactating person or the infant. More data are needed to determine if COVID-19 antibodies present in breastmilk convey protection against SARS-CoV-2 infection for infants.
Which immunocompromised people should receive an additional primary series dose or subsequent booster doses?
The schedule of COVID-19 vaccination has become increasingly complex with the introduction of new eligible age groups and new vaccine products. Please review the CDC “At -A-Glance” COVID-19 Vaccination Schedules (pdf) for the current recommended vaccination schedules for each vaccine for immunocompetent and immunocompromised people in each eligible age group: www.cdc.gov/vaccines/covid-19/downloads/COVID-19-vacc-schedule-at-a-glance-508.pdf.
Although the benefit of the additional primary dose of mRNA vaccine for a moderately or severely immunocompromised person is not precisely known, evidence shows it is safe and can provide better protection than the standard primary series.
Immunocompromised people who receive an additional primary dose 28 days or more after dose 2 should be counseled that they may still have a reduced immune response to COVID-19 vaccination. They should be advised to continue other recommended infection prevention measures, such as wearing a face mask and avoiding crowds, to limit their risk of exposure to the SARS-CoV-2 virus. Healthcare providers should consult current guidelines for the use of Evusheld (tixagevimab and cilgavimab, Astrazeneca) for pre-exposure prophylaxis of moderately or severely immunocompromised adults, in addition to vaccination.
Exactly which immunocompromised groups are recommended to receive an additional primary dose of mRNA vaccine?
The age groups of immunocompromised people eligible for an additional primary series dose are people age 5 years or older (Pfizer-BioNTech), people age 6 months or older (Moderna), and people 18 or older (Janssen). An additional primary series dose is not recommended for Pfizer-BioNTech recipients under age 5 years because all children in that age group are recommended to receive a 3-dose primary series. An additional primary series dose also is not recommended for adults who receive a 2-dose primary series of Novavax vaccine at this time.
Recommendations for booster doses beyond the primary series also vary by age and product type. See the CDC At-A-Glance COVID-19 Vaccination Schedules for details: www.cdc.gov/vaccines/covid-19/downloads/COVID-19-vacc-schedule-at-a-glance-508.pdf.
The conditions and treatments that may result in moderate or severe immunocompromise in these eligible age groups include but are not limited to:
Active treatment for solid tumor and hematologic malignancies
  Receipt of solid-organ transplant and taking immunosuppressive therapy
  Receipt of CAR-T-cell or hematopoietic stem cell transplant (within 2 years of transplantation or taking immunosuppression therapy)
  Moderate or severe primary immunodeficiency (such as DiGeorge syndrome or Wiskott-Aldrich syndrome)
  Advanced or untreated HIV infection
  Active treatment with high-dose corticosteroids (in other words, 20 mg or more of prednisone or equivalent per day), alkylating agents, antimetabolites, transplant-related immunosuppressive drugs, cancer chemotherapeutic agents classified as severely immunosuppressive, tumor-necrosis factor (TNF) blockers, and other biologic agents that are immunosuppressive or immunomodulatory
Additional factors to consider in assessing the general level of immune competence in a patient include disease severity, duration, clinical stability, complications, comorbidities, and any potentially immune-suppressing treatment. A patient’s clinical care team is in the best position to evaluate the degree of immunocompromise and timing of vaccination.
For additional information, please review CDC's interim clinical considerations for this population: www.cdc.gov/vaccines/covid-19/clinical-considerations/interim-considerations-us.html#immunocompromised.
I have an oncology patient who was up to date on COVID-19 vaccination but is now in need of hematopoietic cell transplant (HCT). Will she require revaccination after HCT?
Yes. According to CDC’s interim clinical considerations for the use of COVID-19 vaccines, recipients of HCT or CAR-T-cell therapy who received one or more doses of COVID-19 vaccine prior to or during treatment should be revaccinated (i.e., complete primary vaccination and any recommended booster doses) for any doses received before or during treatment. Any revaccination doses should be given with an mRNA vaccine and should start at least 3 months (12 weeks) after transplant or CAR-T-cell therapy. The patient’s clinical team is best positioned to determine the degree of immune compromise, need for revaccination, and appropriate timing of revaccination.
CDC Emergency Use Instructions (EUI) for each mRNA vaccine product provide additional details on revaccination of patients in these circumstances. They are accessible on CDC’s EUI main page: www.cdc.gov/vaccines/covid-19/eui/index.html.
My patient receives periodic infusions of rituximab for immunosuppressive treatment of an immune system disorder. Should we try to coordinate the timing of his COVID-19 vaccinations around his infusion schedule?
According to CDC's interim clinical considerations for the use of COVID-19 vaccines, whenever possible, COVID-19 vaccines should be administered at least 2 weeks before initiation or resumption of immunosuppressive therapies. For patients who receive B-cell-depleting therapies on a continuing basis, COVID-19 vaccines should be administered approximately 4 weeks before the next scheduled therapy.
CDC also notes that timing of COVID-19 vaccination should take into consideration current or planned immunosuppressive therapies, optimization of both the patient's medical condition and response to vaccination, and individual benefits and risks.
Should I conduct serologic testing or cellular immune testing before or after offering an additional primary dose of mRNA vaccine to an immunocompromised patient?
No. Serologic testing or cellular immune testing before or after an additional primary dose (outside the context of research studies) is not recommended.
Does it matter which brand of mRNA vaccine I give to an immunocompromised person who is recommended to receive an additional primary dose?
CDC recommends that the additional primary dose be given at least 28 days after dose 2 of an mRNA vaccine or after the single primary dose of Janssen vaccine. If mRNA vaccine is used for the primary series, the 3rd dose should be the same brand as the first two doses of the primary series. However, if the same brand is unavailable, you may administer the other mRNA vaccine. If using Moderna, a full primary series dose should be administered as the additional primary dose. Either mRNA vaccine may be used as the additional primary dose for a recipient of a primary dose of Janssen vaccine.
Novavax vaccine is authorized only for use as a 2-dose primary series vaccine and is not intended to be used in a mixed primary series schedule with mRNA or Janssen vaccines. At this time, no additional primary series dose is recommended for immunocompromised adults who receive a 2-dose Novavax vaccine primary series.
Note that immunocompromised children age 6 months through 4 years who receive a standard 3-dose primary series of Pfizer-BioNTech vaccine are not recommended to receive an additional (fourth) primary series dose.
My patient takes high dose steroids and received a single dose of Janssen COVID-19 Vaccine (Johnson & Johnson) in late March 2021. He fits the definition for moderate or severe immunocompromise. Should I give him an additional primary dose of Janssen vaccine?
All recipients of a primary dose of Janssen vaccine should receive an additional primary dose of either mRNA vaccine at least 28 days later. They should then receive a booster dose of COVID-19 vaccine (preferably an mRNA vaccine) at least 2 months (8 weeks) after their additional primary dose and a second booster dose of an mRNA vaccine at least 4 months after their first booster dose, for a total of 4 doses. When Moderna vaccine is used as an additional primary dose in a person age 12 years or older, administer a 100 mcg primary series dose. When Moderna vaccine is used as a booster dose in an adult age 18 years or older, administer a 50-mcg booster dose. Only mRNA vaccines are authorized for use as a second booster dose, which may be given at least 4 months after the first booster dose.
For all vaccination schedule options, including the schedule for an immunocompromised person who received a primary Janssen vaccine dose, refer to the At-A-Glance COVID-19 Vaccination Schedules document from CDC: www.cdc.gov/vaccines/covid-19/downloads/COVID-19-vacc-schedule-at-a-glance-508.pdf.
My patient, age 45, is immunocompromised and is recommended to receive an additional primary dose of mRNA COVID-19 vaccine, but it has already been more than 6 months since his second mRNA dose. What do I do now?
The patient should receive his third primary dose now, using the same brand as the first two doses. If the primary series is Moderna, a full 100 mcg additional primary dose should be used.
For all recommended COVID-19 vaccination schedule options, see the At-A-Glance COVID-19 Vaccination Schedules document from CDC: www.cdc.gov/vaccines/covid-19/downloads/COVID-19-vacc-schedule-at-a-glance-508.pdf.
My patient is medically complex and severely immunocompromised and our clinical team has concerns that the recommended schedule of COVID-19 vaccination for immunocompromised patients may not be adequate. Does CDC permit any latitude in the COVID-19 vaccination schedule for such patients?
CDC's interim clinical considerations now state that, on a case-by-case basis, providers caring for moderately or severely immunocompromised patients may administer mRNA COVID-19 vaccines outside of the FDA and CDC dosing intervals based on clinical judgment when the benefits of vaccination are deemed to outweigh the potential and unknown risks for the recipient. However, CDC cautions that providers should not routinely administer doses of COVID-19 vaccine beyond those recommended.
Administering Vaccines Back to top
How are COVID-19 vaccines administered?
CDC has prepared a quick reference guide for preparation and administration of each COVID-19 vaccine, with the exception of the Moderna product with a blue cap and purple label border for ages 6 years through 11 years:
Pfizer-BioNTech COVID-19 Vaccine, age 12 years and older (purple cap, dilute before use): www.cdc.gov/vaccines/covid-19/info-by-product/pfizer/downloads/prep-and-admin-summary.pdf
Pfizer-BioNTech COVID-19 Vaccine, age 12 years and older (gray cap, do not dilute): www.cdc.gov/vaccines/covid-19/info-by-product/pfizer/downloads/gray-cap-prep-and-admin-summary.pdf
  Pfizer-BioNTech COVID-19 Vaccine, age 5 through 11 years (orange cap, dilute before use): www.cdc.gov/vaccines/covid-19/info-by-product/pfizer/downloads/Pfizer_PED_PrepAdmin.pdf
  Pfizer-BioNTech COVID-19 Vaccine, age 6 months through 4 years (maroon cap, dilute before use): www.cdc.gov/vaccines/covid-19/info-by-product/pfizer/downloads/infant-prep-admin.pdf
  Moderna COVID-19 Vaccine (red cap, blue label border), age 18 years and older: www.cdc.gov/vaccines/covid-19/info-by-product/moderna/downloads/prep-and-admin-summary.pdf
  Moderna COVID-19 Vaccine (dark blue cap with magenta [hot pink] label border) age 6 months through 5 years: www.cdc.gov/vaccines/covid-19/info-by-product/moderna/downloads/infant-prep-admin-summary.pdf
  Novavax COVID-19 Vaccine, age 18 years and older: www.cdc.gov/vaccines/covid-19/info-by-product/novavax/downloads/novavax-prep-admin-summary.pdf
  Janssen COVID-19 Vaccine, age 18 years and older: www.cdc.gov/vaccines/covid-19/info-by-product/janssen/downloads/Janssen-Prep-and-Admin-Summary.pdf
Has CDC provided clinical guidance on what to do if an error occurs while administering COVID-19 vaccinations?
Yes. CDC has published an appendix to its interim clinical considerations for the use of COVID-19 vaccines to address a wide range of errors in vaccine administration. It includes a detailed table outlining actions to take after an error has occurred: www.cdc.gov/vaccines/covid-19/clinical-considerations/interim-considerations-us-appendix.html#appendix-c.
Errors addressed include the following:
Incorrect route or site
  Incorrect age (including administration of a formulation or brand of vaccine to a person in an age group not authorized or approved for that vaccine)
  Incorrect dosing interval
  Incorrect dose (high or low)
  Administration after improper storage conditions
  Administration after the expiration/beyond use date
  Diluent errors (wrong diluent, too much or too little) with the Pfizer-BioNTech vaccines
Ask the Experts refers our readers to these CDC resources for the most current and comprehensive guidance on COVID-19 vaccine administration errors and how to manage them.
A dose of COVID-19 vaccine was administered subcutaneously instead of by the intramuscular route. Does the dose need to be repeated?
No. CDC does not recommend repeating the dose of any COVID-19 vaccine in circumstances where the dose is administered in an incorrect route or an incorrect site (i.e., not in the deltoid or anterolateral thigh).
During vaccination, the needle came loose and vaccine leaked out around it. Do we need to repeat the dose?
It depends on how much of the dose was successfully administered. If, in your judgment, the patient received at least half of the vaccine dose, do not repeat the dose. However, if you judge that less than half the dose was administered, revaccinate the recipient immediately (no minimum interval) with a full dose in the opposite arm.
Scheduling Vaccines Back to top
Where can I find the latest information on scheduling COVID-19 vaccines?
The recommended schedules for COVID-19 vaccines vary by brand, age group, and by the presence of moderate or severe immunocompromise. To obtain the current COVID-19 primary and booster vaccination schedules for each vaccine and age group (beginning at 6 months of age), including the schedules for people with moderate or severe immunocompromise, please refer to CDC’s printable At-A-Glance COVID-19 Vaccination Schedules: www.cdc.gov/vaccines/covid-19/downloads/COVID-19-vacc-schedule-at-a-glance-508.pdf.
Always check the date at the bottom of the document after new changes are announced to be sure you are using the most current version. You may also verify whether you are using the most current documents by checking Immunize.org’s regularly updated Checklist of Current Versions of U.S. COVID-19 Vaccination Guidance and Clinic Support Tools: www.immunize.org/catg.d/p3130.pdf.
If a patient does not come back on time for the second dose of an mRNA COVID-19 vaccine, do we need to re-start the vaccine series?
No. Regardless of the interval, simply administer the second dose to complete the series.
What if the patient gets the second dose of an mRNA COVID-19 vaccine early?
Primary series, additional primary series, or first booster doses administered more than 4 days before the minimum recommended interval should be repeated after the recommended minimum interval between doses: 21 days between Pfizer-BioNTech dose 1 and dose 2; 28 days between Moderna dose 1 and dose 2; 28 days between dose 2 and dose 3 for patients requiring an additional primary series dose of either product; 3 months between final primary dose and first booster dose. Doses administered within a grace period of 4 days or fewer from the recommended date are considered valid and do not need to be repeated.
A second booster dose that is administered before the recommended 4-month minimum interval after the first booster dose interval does not need to be repeated.
If the second dose of mRNA COVID-19 vaccine may be given before the recommended interval because of the 4-day grace period, should we offer that option routinely?
No. People should not be scheduled to receive dose 2 earlier than recommended (21 days for Pfizer-BioNTech, 28 days for Moderna). Schedulers should offer second dose appointments beginning on the date of the recommended interval or later. CDC guidance allows for dose 2 to be given up to 4 days before the recommended interval in order to avoid missed vaccination opportunities when a recipient unexpectedly arrives early and might not return on schedule. The series never needs to be restarted due to a delay in the second dose.
If a patient inadvertently received a different brand of vaccine as a second dose, does it need to be repeated with the correct brand?
No. If a recipient is inadvertently given a different brand of vaccine for the second dose, the CDC does not recommend that the patient receive a repeat dose of either product. A person who receives a mixed primary series of one dose of mRNA vaccine and one dose of Novavax vaccine may follow the age-appropriate mRNA or Novavax schedule for subsequent doses.
If a patient inadvertently received a different brand of vaccine as a second dose, does it need to be repeated with the correct brand?
No. If a recipient is inadvertently given a different brand of vaccine for the second dose, the CDC does not recommend that the patient receive a repeat dose of either product. A person who receives a mixed primary series of one dose of mRNA vaccine and one dose of Novavax vaccine may follow the age-appropriate mRNA or Novavax schedule for subsequent doses.
A 3-year-old child in my practice who received a first dose of Moderna COVID-19 vaccine at an outside clinic just received a dose of Pfizer-BioNTech COVID-19 vaccine as dose 2 instead of the second dose of Moderna vaccine. Do we need to give another dose?
Children who are age 6 months through 4 years and receive different mRNA products for the first two doses need to follow a 3-dose schedule. The third dose of either mRNA vaccine should be administered 8 weeks after the second dose to complete the 3-dose primary series.
If a patient received a dose of Novavax COVID-19 Vaccine, but cannot locate a second dose of Novavax vaccine, what should we do?
CDC recommends that, in general, the same vaccine product should be used for all doses in the primary series.
In the following exceptional situations, a different, age-appropriate COVID-19 vaccine may be administered to complete a primary series at a minimum interval of 28 days from the last COVID-19 vaccine dose. No VAERS report is required.
The same vaccine is not available
  The first dose is unknown
  A person starts but is unable to complete a primary series with the same COVID-19 vaccine due to a contraindication.
People who receive Janssen COVID-19 Vaccine after a dose of another COVID-19 vaccine should be considered to have received a valid, single-dose Janssen primary series.
What are COVID-19 Vaccine Emergency Use Instructions (EUI) and to whom do they apply?
CDC has issued emergency use instructions (EUI) for the use of the FDA-licensed mRNA vaccines (adolescent/adult Pfizer-BioNTech COVID-19 Vaccine [Comirnaty] or Moderna COVID-19 Vaccine [Spikevax]), that differ from the FDA-approved package insert. These instructions apply to certain people who received primary series COVID-19 vaccination with vaccines not authorized or approved by the FDA (either in another country or as part of a clinical trial) and to people who may need revaccination following hematopoietic cell transplant (HCT) or CAR-T-cell therapy.
Vaccine schedule guidance is provided by age for the general population and for individuals with moderate or severe immunocompromise.
All CDC EUI resources, including the Pfizer-BioNTech and Moderna EUI Fact Sheets for Healthcare Providers, as well as those for recipients and caregivers (available in English and Spanish), are at this site: www.cdc.gov/vaccines/covid-19/eui/index.html.
We have a patient who was vaccinated with a COVID-19 vaccine in another country. What do we do?
CDC has issued a detailed set of emergency use instructions (EUI) that provides a legal framework for the use of licensed COVID-19 vaccines to vaccinate people who have received vaccines not authorized or licensed in the United States. A key factor in determining next steps is whether or not the vaccine administered in another country is listed for emergency use by the World Health Organization (WHO-EUL), which signals that the vaccine has been reviewed and considered acceptable for use by WHO experts.
CDC has outlined each vaccination option on its website. For specific cases, please review CDC’s detailed EUI table here: www.cdc.gov/vaccines/covid-19/clinical-considerations/interim-considerations-us-appendix.html#appendix-a.
A list of the vaccines that have already received WHO-EUL status is available here: https://extranet.who.int/pqweb/vaccines/vaccinescovid-19-vaccine-eul-issued.
My patient was vaccinated in a clinical trial with a vaccine that is not yet authorized for use by the FDA. How should we evaluate his need for vaccination now?
People vaccinated as part of a clinical trial with a vaccine not authorized or approved for use in the United States are covered under the CDC’s Emergency Use Instructions (EUI).
CDC has provided specific guidance for evaluating the current vaccination needs of people who participated in a COVID-19 vaccine clinical trial here: www.cdc.gov/vaccines/covid-19/clinical-considerations/interim-considerations-us-appendix.html#appendix-b.
What should be done if a patient scheduled for vaccination is exposed to COVID-19 and quarantined or is isolated for suspected or confirmed SARS-CoV-2 infection?
In general, the people scheduled for COVID-19 vaccination who are exposed to SARS-CoV-2 virus and quarantined should reschedule vaccination after their quarantine period has ended in order to avoid the risk of exposing vaccinators to the virus.
People diagnosed with SARS-CoV-2 infection before a scheduled vaccination should defer vaccination until after recovery and the end of the isolation period to avoid the risk of exposing vaccinators to the virus. Although waiting longer to vaccinate after infection is not necessary, people who recently had SARS-CoV-2 infection may consider delaying a primary series dose or their first or second COVID-19 vaccine booster dose by 3 months from symptom onset or positive test (if infection was asymptomatic). According to CDC, increasing the time between infection and vaccination may result in an improved immune response to vaccination. At this time, there is evidence of a low risk of reinfection in the weeks following infection. A recipient’s individual risks for severe disease and current COVID-19 conditions in the community should be taken into account when deciding whether to delay vaccination up to 3 months after infection.
Residents or patients with a known COVID-19 exposure in congregate healthcare settings (e.g., long-term care facilities) or congregate non-healthcare settings (e.g., correctional facilities, homeless shelters) may be vaccinated. In these settings, exposure to and transmission of SARS-CoV-2 can occur repeatedly for long periods of time, and healthcare personnel and other staff are already in close contact with residents. People residing in congregate settings (healthcare and non-healthcare) who have had an exposure and are awaiting SARS-CoV-2 testing results may be vaccinated if they do not have symptoms consistent with COVID-19. Vaccinators should employ appropriate infection prevention and control procedures.
Can COVID-19 vaccine recipients be given other vaccines at the same visit?
Yes, with one exception, COVID-19 vaccines and other vaccines may be administered without regard to timing. Extensive experience with non-COVID-19 vaccines has demonstrated that the immune response and side effects following vaccination are generally similar when vaccines are administered simultaneously and when vaccines are administered alone.
The timing of COVID-19 vaccination following recent orthopoxvirus (e.g., monkeypox) vaccination is the one exception to the principle that COVID-19 vaccines may be administered without any regard to the timing of other vaccines. There is a small risk for myocarditis after receipt of ACAM2000 orthopoxvirus vaccine and an even more rare risk for myocarditis after receipt of mRNA COVID-19 vaccines (Moderna and Pfizer-BioNTech) or Novavax COVID-19 Vaccine. There is an unknown risk for myocarditis after Jynneos orthopoxvirus vaccination. For this reason, people, particularly adolescent or young adult males, might consider waiting 4 weeks after orthopoxvirus vaccination (either Jynneos or ACAM2000) before receiving a Moderna, Novavax, or Pfizer-BioNTech COVID-19 vaccine.
If an orthopoxvirus vaccine is recommended for a person to prevent infection in the setting of a monkeypox outbreak, orthopoxvirus vaccination should not be delayed because of recent receipt of a Moderna, Novavax, or Pfizer-BioNTech COVID-19 vaccine; no minimum interval between COVID-19 vaccination with these vaccines and vaccination with Jynneos or ACAM2000 is necessary.
My patient is due for a second dose of recombinant zoster vaccine (Shingrix, GSK). However, the patient is eligible to receive COVID-19 vaccine and wants to be vaccinated against COVID-19 as soon as possible. What should we advise our patient about scheduling the second Shingrix dose?
Your patient may choose to receive the vaccines at the same visit or separately, without regard to the timing interval. It is unknown whether side effects would be increased with coadministration. In general, when deciding whether to coadminister other vaccines with COVID-19 vaccine, you should consider whether the patient is behind or at risk of becoming behind on recommended vaccines, their risk of vaccine-preventable disease (e.g., during an outbreak or occupational exposures), and the reactogenicity profile of the vaccines.
When multiple vaccines are administered at a single visit, administer each injection in a different injection site. For adolescents and adults, the deltoid muscle may be used for more than one injection, though injection sites should be at least one inch apart. It is generally preferable to administer reactogenic vaccines such as Shingrix and COVID-19 vaccine in different arms, if possible. If the patient prefers both injections in the same deltoid, that is also acceptable.
Immunize.org has developed a one-page guide to administering multiple intramuscular vaccinations to an adult at one visit: www.immunize.org/catg.d/p2030.pdf.
A patient had a routine tuberculin skin test (TST) placed the day before the patient's appointment for a COVID-19 vaccine. Should we proceed with vaccination or do we need to reschedule?
CDC advises that COVID-19 vaccination should not be delayed because of testing for tuberculosis (TB) infection. Testing for TB infection with one of the immune-based methods, either the tuberculin skin test (TST) or an interferon-gamma release assay (IGRA), can be done before, after, or during the same encounter as COVID-19 vaccination: www.cdc.gov/vaccines/covid-19/clinical-considerations/interim-considerations-us.html#special-populations.
How does the use of monoclonal antibodies or convalescent plasma to treat or prevent COVID-19 affect the scheduling of COVID-19 vaccination?
In February 2022, CDC updated its guidance on the scheduling of COVID-19 vaccination around monoclonal antibodies or convalescent plasma. CDC now recommends that COVID-19 vaccination does NOT need to be delayed following receipt of monoclonal antibodies or convalescent plasma.
In people who previously received a COVID-19 vaccine, administration of tixagevimab/cilgavimab (Evusheld, AstraZeneca) for pre-exposure prophylaxis (PrEP) should be deferred for at least two weeks after vaccination, per the product's emergency use authorization.
Contraindications and Precautions Back to top
Please describe the contraindications for each COVID-19 vaccination.
We refer our readers to CDC's updated set of contraindications and precautions to vaccination with COVID-19 vaccines, located in table 4 of its interim clinical considerations for the use of COVID-19 vaccines in the United States: www.cdc.gov/vaccines/covid-19/clinical-considerations/interim-considerations-us.html#contraindications.
What are the precautions to COVID-19 vaccination?
We refer our readers to CDC's updated set of contraindications and precautions to COVID-19 vaccination, located in table 4 of its interim clinical considerations for the use of COVID-19 vaccines: www.cdc.gov/vaccines/covid-19/clinical-considerations/interim-considerations-us.html#contraindications.
Can people who are immunocompromised or who have autoimmune disease be vaccinated with COVID-19 vaccines?
Yes, they may be vaccinated as long as they do not have a contraindication to vaccination. Antibody testing is not recommended to assess for immunity to SARS-CoV-2 following COVID-19 vaccination.
Recipients should be counseled about the unknown and variable effectiveness of COVID-19 vaccination in immunocompromised populations and the potential for reduced immune responses. They should maintain other practices, such as wearing a mask in public and avoiding crowds, to reduce their risk of exposure to SARS-CoV-2. Healthcare providers treating patients with moderate to severe immunocompromise who are not expected to respond effectively to vaccination should consider the use of Evusheld (AstraZeneca) antibody therapy for pre-exposure prophylaxis.
The current immunization schedules for each available vaccine product for people ages 6 months or older with moderate or severe immunocompromise are listed in CDC’s At-A-Glance COVID-19 Vaccination Schedules document: www.cdc.gov/vaccines/covid-19/downloads/COVID-19-vacc-schedule-at-a-glance-508.pdf.
CDC provides detailed considerations for vaccination of people with moderate or severe immunocompromise here: www.cdc.gov/vaccines/covid-19/clinical-considerations/interim-considerations-us.html#immunocompromised.
Are there any common types of allergies that are neither contraindications nor precautions to vaccination?
Allergic reactions (including severe allergic reactions) not related to vaccines (COVID-19 or other vaccines) or injectable therapies, such as allergic reactions related to food, pet, venom, or environmental allergies, or allergies to oral medications (including the oral equivalents of injectable medications), are not a contraindication or precaution to COVID-19 vaccination. The vial stoppers of COVID-19 vaccines are not made with natural rubber latex, and there is no contraindication or precaution to vaccination for people with a latex allergy. COVID-19 vaccines do not contain eggs, gelatin, or metals.
A self-limited, delayed-onset local reaction around the injection site ("COVID arm") has been reported by some mRNA vaccine recipients several days after vaccination (see next question). This type of reaction is not a precaution or contraindication to future doses of the same vaccine.
A vaccine recipient reported experiencing a red, itchy, swollen patch of skin that developed several days after vaccination around the injection site of her first COVID-19 vaccine dose. It resolved after a few days. Is this a contraindication? Should this alter our plans for dose two?
This condition is not rare and is also known as "COVID arm". She should receive dose two as recommended. Individuals with only a delayed-onset local reaction (e.g., redness, induration, itching) around the injection site area after the first vaccine dose do not have a contraindication or precaution to the second dose.
These delayed-onset local reactions are sometimes quite large but are self-limited. It is not known whether individuals who experienced a delayed-onset injection site reaction after the first dose will experience a similar reaction after the second dose. However, these reactions are not believed to represent an increased risk for anaphylaxis after a subsequent dose. Thus, individuals with such delayed injection site reactions after the first mRNA COVID-19 vaccine dose should receive the second dose using the same vaccine product as the first dose and at the recommended interval, preferably in the opposite arm.
Patients who experience "COVID arm" may take an antihistamine if it is itchy or a pain medication such as acetaminophen or a non-steroidal anti-inflammatory (NSAID) if it is painful.
Patients concerned about the risk of allergic reaction or side effects following COVID-19 vaccination are asking if they should take acetaminophen, aspirin, and/or antihistamines before receiving COVID-19 vaccination. What does CDC advise?
Medications to reduce fever and pain (e.g., acetaminophen, non-steroidal anti-inflammatory drugs) may be taken to treat post-vaccination local or systemic symptoms, if medically appropriate. However, routine administration of such medications before vaccination is not recommended because information on the impact of such use on COVID-19 vaccine-induced antibody responses is not available at this time.
Administration of antihistamines before COVID-19 vaccination to prevent allergic reactions is not recommended. Antihistamines do not prevent anaphylaxis, and their use might mask cutaneous symptoms, which could delay diagnosis and management of anaphylaxis.
It is not recommended that people take aspirin or an anticoagulant before vaccination with the Janssen COVID-19 vaccine or any other FDA-authorized COVID-19 vaccine unless they take these medications as part of their routine medications.
Is COVID-19 vaccination contraindicated in a patient who has had immune-mediated thrombosis with thrombocytopenia syndrome (TTS)?
It is contraindicated to administer Janssen COVID-19 Vaccine to persons with a history of TTS following receipt of the Janssen COVID-19 Vaccine or any other adenovirus vector-based COVID-19 vaccines (e.g., AstraZeneca COVID-19 Vaccine, which is not authorized or approved in the United States). Individuals who have experienced TTS following Janssen COVID-19 Vaccine may be vaccinated with a booster dose of mRNA vaccine 2 months (8 weeks) after receipt of the Janssen vaccine, if their clinical condition is stabilized. Individuals with a history of an episode of an immune-mediated TTS, such as HIT, should be offered an mRNA or Novavax COVID-19 vaccine for the primary series.
Additional clinical considerations concerning the use of Janssen COVID-19 Vaccine are available from CDC here: www.cdc.gov/vaccines/covid-19/clinical-considerations/interim-considerations-us.html#considerations-Janssen.
My patient has a history of deep venous thrombosis (DVTs). Is that a precaution or contraindication to vaccination with the Janssen COVID-19 Vaccine?
Venous thromboembolism (VTE), defined as deep vein thrombosis, pulmonary embolism, or both, are common. The biologic mechanisms for VTE (as well as arterial thrombi) differ from the underlying immune-mediated mechanism for thrombosis with thrombocytopenia syndrome (TTS). Experts believe that the presence of risk factors for VTE does not make individuals more susceptible to TTS after vaccination with the Janssen vaccine. As with the general population, other age-appropriate authorized or approved COVID-19 vaccines are preferred over Janssen vaccine for these recipients.
Is there a precaution or contraindication against vaccination of children or adults who have recovered from COVID-19 Multisystem Inflammatory Syndrome (MIS-C or MIS-A)?
There are limited data on the safety of COVID-19 vaccines in people who have had MIS-C or MIS-A from SARS-CoV-2 infection and who have not yet received COVID-19 vaccine. Case-by-case consultation with their clinical team or a specialist (e.g., specialist in infectious diseases, rheumatology, or cardiology) is strongly encouraged. CDC continues to update its clinical considerations for vaccination of children or adults who have experienced MIS-C or MIS-A. Visit this link for the most current clinical considerations for vaccination of children and adults who have experienced this syndrome following SARS-CoV-2 infection: www.cdc.gov/vaccines/covid-19/clinical-considerations/interim-considerations-us.html#covid19-vaccination-misc-misa.
My patient had an episode of myocarditis 5 years ago. Is a history of myocarditis a contraindication or precaution to vaccination with an mRNA or Novavax vaccine?
CDC guidance is that people who have a history of completely resolved myocarditis or pericarditis unrelated to COVID-19 vaccination (e.g., due to SARS-CoV-2 or other viruses) may receive any age-appropriate COVID-19 vaccine that is FDA-approved or FDA-authorized. “Complete resolution” includes resolution of symptoms attributed to myocarditis or pericarditis, as well as no evidence of ongoing heart inflammation or sequelae as determined by the person’s clinical team.
History of myocarditis or pericarditis after a dose of an mRNA (Pfizer-BioNTech or Moderna) COVID-19 vaccine or Novavax COVID-19 Vaccine is a precaution to vaccination with any COVID-19 vaccine, and subsequent doses should generally be avoided.
Complete and current clinical considerations for COVID-19 vaccination of patients with a history of myocarditis are available from CDC here: www.cdc.gov/vaccines/covid-19/clinical-considerations/interim-considerations-us.html#myocarditis-pericarditis.
For additional information about myocarditis and mRNA COVID-19 vaccines, visit www.cdc.gov/vaccines/covid-19/clinical-considerations/myocarditis.html.
My patient has a history of Guillain-Barré syndrome (GBS). Is that a contraindication or precaution to vaccination with any COVID-19 vaccine?
People with a history of GBS can receive any currently FDA-authorized or licensed COVID-19 vaccine. Vaccine safety monitoring suggests an elevated risk of GBS in the 42 days following the Janssen COVID-19 Vaccine, with the highest risk observed in people ages 40 through 64 years. Most reports of GBS have been in males. The risk of this very rare outcome is clearly outweighed by the benefits of vaccination with a COVID-19 vaccine, including Janssen COVID-19 Vaccine in exceptional situations when vaccination with another COVID-19 vaccine is not possible.
Vaccine Safety Back to top
What common side effects are expected after vaccination with mRNA vaccines?
Recipients of mRNA COVID-19 vaccines often experience local (e.g., pain, swelling, redness at the injection site, localized swollen lymph nodes in the armpit of the vaccinated arm) or systemic (e.g., fever, fatigue, headache, chills, body and joint aches) post-vaccination symptoms. Depending on vaccine product (Pfizer-BioNTech vs. Moderna), age group, and vaccine dose, approximately 80–91% of vaccinated people develop at least one local symptom and 55–91% develop at least one systemic symptom following vaccination.
Most systemic post-vaccination symptoms are mild to moderate in severity, occur within the first three days of vaccination, and resolve within 1–3 days of onset. These symptoms are more frequent and severe following the second dose and among younger people compared to older people.
Among children ages 6 months through 4 years (Pfizer-BioNTech) or 6 months through 5 years (Moderna), pain or tenderness at the injection site was the most frequent local reaction. The most common systemic symptom in older children was fatigue; in younger children (ages 6 through 23 months), irritability/crying and drowsiness/sleepiness were most common. Most systemic symptoms were mild to moderate in severity, typically began 1 to 2 days after vaccination, and resolved after 1 to 2 days.
What common side effects are expected after vaccination with Novavax COVID-19 Vaccine?
In clinical trials of Novavax COVID-19 Vaccine, pain or tenderness at the injection site was the most frequently reported local reaction among vaccine recipients; redness and swelling were reported less frequently. Fatigue, headache, and muscle pain were the most commonly reported systemic reactions. Most symptoms were mild to moderate in severity and resolved within 1 to 3 days. Overall, symptoms were more frequent in people ages 18 through 64 years compared to people ages 65 years and older and more frequent after dose 2 than dose 1.
What common side effects are expected after vaccination with Janssen COVID-19 Vaccine (Johnson & Johnson)?
Recipients of the Janssen viral vector vaccine in the phase 3 clinical trial often experienced local or systemic post-vaccination symptoms, though the majority of reported symptoms were mild to moderate in severity and resolved within 1 to 3 days after vaccination. The frequency of any local reaction was higher in participants aged 18 to 59 years than participants age 60 years or older (59.8% vs 35.4%). Pain at the injection site was the most frequently reported solicited local reaction. The frequency of systemic reactions was higher in participants age 18–59 years than participants 60 years or older (61.5% vs 45.3%). For both age groups, fatigue and headache were the most commonly reported systemic reactions. Fever was more common in participants 18–59 years (12.8%) compared to those 60 years or older (3.1%).
What is the thrombosis with thrombocytopenia syndrome, called TTS, associated with the Janssen COVID-19 Vaccine?
TTS is a rare, immune-mediated syndrome that involves acute venous or arterial thrombosis (blood clot) and new onset thrombocytopenia (low platelet count) in patients with no recent known exposure to heparin. The onset of TTS is typically 1 to 2 weeks following vaccination; treatment with heparin, a common anticoagulant used to treat blood clots, worsens the condition. In the U.S., the majority of people with TTS after Janssen COVID-19 vaccination had clots located in cerebral venous sinuses; clots occurred in other unusual locations including in the portal vein and splenic vein, and also included a combination of venous and arterial thromboses.
Cases of TTS following administration of the Janssen COVID-19 Vaccine have been reported in males and females, in a wide age range of individuals 18 years and older, with the highest reporting rate (approximately 1 case per 100,000 doses administered) in females ages 30-49 years; overall, approximately 15% of TTS cases have been fatal.
Based on an updated risk-benefit analysis, including the risk of TTS, use of mRNA COVID-19 vaccines is preferred over the Janssen COVID-19 vaccine for all vaccine-eligible people. The FDA EUA for Janssen vaccine limits its authorized use to people for whom mRNA vaccines are clinically inappropriate or those for whom mRNA vaccination is not feasible. All people who elect to receive a Janssen COVID-19 vaccine booster should be informed about the risk and symptoms of TTS that could occur after vaccination (typically within 2 weeks after receipt), the need to seek immediate medical care should such symptoms develop at any time, and the availability of mRNA COVID-19 vaccines instead of the Janssen COVID-19 Vaccine.
What are the symptoms of TTS and where can I learn more about treatment?
Cases of TTS following administration of the Janssen COVID-19 Vaccine have been reported in males and females, in a wide age range of individuals 18 years and older, with the highest reporting rate (approximately 1 case per 100,000 doses administered) in females ages 30-49 years; overall, approximately 15% of TTS cases have been fatal. Symptom onset typically begins 1 to 2 weeks after vaccination. People should seek medical attention right away if they have any of the following symptoms after receiving the Janssen vaccine:
Shortness of breath
  Chest pain
  Leg swelling
  Persistent abdominal pain
  Severe or persistent headaches or blurred vision
  Easy bruising or tiny blood spots under the skin beyond the site of the injection
Treatment of TTS is different from the treatment of typical blood clots; heparin should be avoided in any patient suspected of TTS until the diagnosis can be ruled out.
For additional clinical guidance, see the CDC Health Alert Network Report from April 13, 2021: emergency.cdc.gov/han/2021/han00442.asp and treatment guidelines from the American Society for Hematology: www.hematology.org/covid-19/vaccine-induced-immune-thrombotic-thrombocytopenia.
Have any COVID-19 vaccines been associated with Guillain-Barré syndrome (GBS)?
Vaccine safety monitoring indicates an increased risk of GBS within 42 days of vaccination with the Janssen COVID-19 Vaccine, with the highest risk among people ages 40 through 64. Most reports have been in males. Although the chance of GBS occurring is extremely low, Janssen vaccine recipients should be counseled to seek medical attention promptly if symptoms of GBS occur, such as progressive muscle weakness. Currently, no association has been observed between GBS and mRNA COVID-19 vaccines.
Moderna or Pfizer-BioNTech mRNA COVID-19 vaccines or Novavax COVID-19 Vaccine are preferred for individuals with a history of GBS. A history of GBS is a precaution for receipt of Janssen vaccine.
Patients who experienced GBS within 6 weeks after Janssen COVID-19 vaccination should not receive future doses of Janssen COVID-19 vaccine. They should be informed of the recommendation for a booster dose 2 months after the first dose and the option to receive an mRNA vaccine for booster doses. Discussions with the clinical team for the patient are encouraged to assist decision-making.
I have both mRNA and Janssen vaccines available. Now that FDA has limited the use of Janssen vaccine, when should I offer the Janssen vaccine?
Use of mRNA COVID-19 vaccines and Novavax vaccine is preferred over Janssen COVID-19 Vaccine for all vaccine-eligible people except in situations where use of an alternative vaccine is not feasible, as described below:
When there is a contraindication to mRNA and Novavax COVID-19 vaccines
  When a person would otherwise remain unvaccinated for COVID-19 due to lack of access to mRNA or Novavax COVID-19 vaccines
  When a person refuses mRNA and Novavax vaccination and chooses to receive the Janssen COVID-19 Vaccine despite the safety concerns identified
All people who elect to receive a Janssen COVID-19 Vaccine booster should be informed about the risk and symptoms of TTS that could occur after vaccination (typically within 2 weeks after receipt), the need to seek immediate medical care should such symptoms develop at any time, and the availability of mRNA and Novavax COVID-19 vaccines instead of the Janssen COVID-19 Vaccine.
Can COVID-19 vaccination lead to fertility problems?
There is no evidence that any of the COVID-19 vaccines affect current or future fertility.
Tell me about mRNA COVID-19 vaccines and the risk of myocarditis and pericarditis.
A rare risk for myocarditis (inflammation of the heart muscle) and/or pericarditis (inflammation of the tissue surrounding the heart) has been observed following receipt of mRNA COVID-19 vaccines and Novavax COVID-19 Vaccine.
Among mRNA vaccine recipients, these rare cases of myocarditis or pericarditis have occurred most frequently in adolescent and young adult males within the first week after receiving the second dose of an mRNA COVID-19 vaccine. The risk appears lower following a booster dose. Myocarditis has been even more rarely reported in children younger than age 12 years after COVID-19 vaccination. Most patients with myocarditis after mRNA COVID-19 vaccination have been hospitalized for short periods, with most completely recovering from their acute symptoms. CDC is assessing long-term outcomes in people with myocarditis after mRNA COVID-19 vaccination
People receiving mRNA vaccines, especially males age 12 through 39, should be counseled about the risk of myocarditis or pericarditis and advised to seek medical attention promptly if they develop chest pain, shortness of breath, or feelings of a fast, fluttering, or pounding heartbeat.
Cases of myocarditis and pericarditis were identified in clinical trials of Novavax COVID-19 Vaccine and have also been reported during post-authorization use outside the United States. These findings suggest that an increased risk for these conditions may be present after receiving Novavax COVID-19 vaccine.
Evidence from other countries indicates that waiting 8 weeks to administer the second mRNA dose can significantly reduce the risk of myocarditis following dose 2; antibody levels after dose 2 may also be higher when given after an 8-week interval. CDC now recommends that an 8-week interval between dose 1 and dose 2 may be optimal for some people age 6 months through 64 years, especially adolescent and young adult males. CDC does not recommend the 8-week dose interval for people who need rapid protection from COVID-19, including adults 65 or older, people with moderate to severe immunocompromise, and in circumstances where rapid protection is desired due to high levels of circulating COVID-19.
CDC's complete interim clinical considerations for COVID-19 vaccination and myocarditis or pericarditis are available here: www.cdc.gov/vaccines/covid-19/clinical-considerations/interim-considerations-us.html#myocarditis-pericarditis.
CDC also has published additional clinical considerations for the evaluation and care of patients with myocarditis or pericarditis following mRNA vaccination: www.cdc.gov/vaccines/covid-19/clinical-considerations/myocarditis.html.
How should patients with allergies presenting for COVID-19 vaccination be evaluated?
Serious allergic reactions, such as anaphylaxis, in the minutes following vaccination are rare but are possible with any vaccine. Every vaccination site should have staff available who are trained and equipped to recognize and respond to signs of anaphylaxis in a vaccine recipient. See this CDC website for additional information about preparing for the management of anaphylaxis: www.cdc.gov/vaccines/covid-19/clinical-considerations/managing-anaphylaxis.html?anaphylaxis-management.html.
Anaphylaxis following vaccination with mRNA COVID-19 vaccines is reported at a rate of approximately 2 to 5 cases per million doses administered.
An immediate allergic reaction to any component or previous dose of an mRNA COVID-19 vaccine is a contraindication to vaccination with both the Pfizer-BioNTech and Moderna vaccines; however, use of the Novavax or Janssen vaccines may not be contraindicated; see the CDC’s COVID-19 interim clinical considerations section on contraindications and precautions for details: www.cdc.gov/vaccines/covid-19/clinical-considerations/interim-considerations-us.html#contraindications.
This CDC chart of vaccine components is designed to assist the triage of patients with various health conditions or allergies: www.cdc.gov/vaccines/covid-19/clinical-considerations/interim-considerations-us-appendix.html#appendix-e.
How long should patients be observed for signs of an immediate allergic reaction following vaccination with a COVID-19 vaccine?
In accordance with general best practices for vaccination, all people should be observed for at least 15 minutes after vaccination for signs of an immediate allergic reaction.
People who should be observed for 30 minutes following COVID-19 vaccination include:
People with a contraindication to one type of COVID-19 vaccine who are receiving a different type (for example, a person with a contraindication to mRNA COVID-19 vaccines who receives Novavax vaccine should be observed for 30 minutes following Novavax vaccination)
  People with a history of non-severe, immediate (onset within 4 hours) allergic reaction after a previous dose of COVID-19 vaccine
  People with a history of an immediate allergic reaction of any severity to a non-COVID-19 vaccine or injectable therapies
  People with a history of anaphylaxis due to any cause
Where can I find the latest information on allergic reactions and COVID-19 vaccines?
Visit this CDC website for the latest information: www.cdc.gov/coronavirus/2019-ncov/vaccines/safety/allergic-reaction.html.
For information about how to triage people with a history of allergy who present for COVID-19 vaccination, see CDC’s triage guidance: www.cdc.gov/vaccines/covid-19/clinical-considerations/interim-considerations-us-appendix.html#appendix-e.
I have heard that the FDA has specific reporting requirements for healthcare providers who administer COVID-19 vaccines under EUA. What are they?
Adverse events that occur in a recipient following COVID-19 vaccination should be reported to the Vaccine Adverse Event Reporting System (VAERS). Vaccination providers are required by the FDA to report the following that occur after COVID-19 vaccination under Emergency Use Authorization:
All vaccine administration errors
  Serious adverse events, including thrombotic thrombocytopenic syndrome (TTS), Guillain-Barré syndrome (GBS), or myocarditis
  Cases of Multisystem Inflammatory Syndrome (MIS) in children or adults
  Cases of COVID-19 that result in hospitalization or death
Reporting is encouraged for any other clinically significant adverse event even if it is uncertain whether the vaccine caused the event. Information on how to submit a report to VAERS is available at https://vaers.hhs.gov or by calling 1-800-822-7967.
How is the safety of COVID-19 vaccines being monitored?
Multiple national surveillance systems are being used to monitor the safety of new COVID-19 vaccines in different ways. Please see this CDC website for additional information on each system: www.cdc.gov/coronavirus/2019-ncov/vaccines/safety.html.
What is v-safe?
CDC's v-safe program is a smartphone-based tool that uses text messaging and web surveys to provide personalized health check-ins after a person receives a COVID-19 vaccination. It also provides second dose reminders. Participation is voluntary; pregnant individuals are especially encouraged to participate in the v-safe pregnancy registry. Vaccine recipients may sign up for the program after receiving the first dose. For more information, visit www.cdc.gov/coronavirus/2019-ncov/vaccines/safety/vsafe.html.
Is compensation for an injury resulting from an EUA COVID-19 vaccine available through the National Vaccine Injury Compensation Program (VICP)?
No. The COVID-19 vaccines are not part of the VICP. The COVID-19 vaccines are part of a similar program called the Countermeasures Injury Compensation Program (CICP). For more information, visit this web page: www.hrsa.gov/cicp.
Storage and Handling Back to top
Where can I find details about the storage and handling of COVID-19 vaccines?
You may find guidance on the storage and handling of each authorized or licensed COVID-19 vaccine in the CDC’s Vaccine Storage and Handling Toolkit addendum on COVID-19 vaccines: www.cdc.gov/vaccines/hcp/admin/storage/toolkit/storage-handling-toolkit.pdf.
CDC has produced a printable quick reference guide summarizing the storage and handling requirements for each authorized COVID-19 vaccine:
Pfizer-BioNTech COVID-19 Vaccine:
°
Purple cap (age 12+ years): www.cdc.gov/vaccines/covid-19/info-by-product/pfizer/downloads/storage-summary.pdf
° Gray cap (age 12+ years): www.cdc.gov/vaccines/covid-19/info-by-product/pfizer/downloads/gray-cap-storage-summary.pdf
° Orange cap (age 5 through 11 years): www.cdc.gov/vaccines/covid-19/info-by-product/pfizer/downloads/Pfizer_PED_StorageHandling_Summary.pdf
° Maroon cap (age 6 months through 4 years): www.cdc.gov/vaccines/covid-19/info-by-product/pfizer/downloads/infant-storage-handling-summary.pdf
Moderna COVID-19 Vaccine (all formulations in one document): www.cdc.gov/vaccines/covid-19/info-by-product/moderna/downloads/Moderna-Storage-Summary-508.pdf
Novavax COVID-19 Vaccine: www.cdc.gov/vaccines/covid-19/info-by-product/novavax/downloads/novavax-storage-handling-summary.pdf
Janssen COVID-19 Vaccine: www.cdc.gov/vaccines/covid-19/info-by-product/janssen/downloads/janssen-storage-handling-summary.pdf
Immunize.org has assembled key COVID-19 vaccine storage and handling resources in its section on Clinic Resources and Tools at our “Vaccines: COVID-19” main page: www.immunize.org/covid-19/#tools.
Under what conditions may we transport COVID-19 vaccines? Is transport of a partial vial or predrawn syringe ever permissible?
Although routine transportation of vaccines to different facilities is not generally recommended, there are times when this is necessary. CDC recommends transporting COVID-19 vaccine in vials and always with a continuous temperature monitoring device to ensure adherence to authorized storage times and temperatures. Because liquid mRNA COVID-19 vaccines should not be shaken vigorously, it is preferred to transport vials in their solid frozen state or to initiate transport while frozen, if they are not already thawed. Never re-freeze vaccine that is already thawed. Moderna recommends that thawed vials of liquid be cushioned to minimize agitation during transport. A partially used vial may be transported (e.g., in the process of vaccinating homebound individuals), but cannot be transferred from one provider to another nor can it be transported across state lines. Details are provided in the 2022 CDC Vaccine Storage and Handling Toolkit addendum on COVID-19 vaccines: www.cdc.gov/vaccines/hcp/admin/storage/toolkit/storage-handling-toolkit.pdf.
There may be instances when the only option is to transport vaccine in a predrawn syringe. CDC refers to the U.S. Pharmacopeia (USP) guidance for transporting predrawn vaccine in syringes in the USP COVID-19 Vaccine Toolkit: Operational Considerations for Healthcare Practitioners. The complete document provides detailed guidance on COVID-19 vaccine transport and is available for download from this site: www.usp.org/covid-19/vaccine-handling-toolkit.
Back to top
This page was updated on August 11, 2022.
This page was reviewed on August 3, 2022.
 
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This website is supported in part by a cooperative agreement from the National Center for Immunization and Respiratory Diseases (Grant No. 1NH23IP922654) at the Centers for Disease Control and Prevention (CDC) in Atlanta, GA. The website content is the sole responsibility of IAC and does not necessarily represent the official views of CDC.