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Administering Vaccines
Billing and Reimbursement
Combination Vaccines
Contraindications and Precautions
COVID-19 and Routine Vac
Documenting Vaccination
Hepatitis A
Hepatitis B
Meningococcal ACWY
Meningococcal B
Scheduling Vaccines
Storage and Handling
Travel Vaccines
Vaccine Recommendations
Vaccine Safety
Varicella (chickenpox)
Zoster (shingles)
Disease Issues Administering Vaccines
Vaccine Recommendations Scheduling Vaccines
Vaccine Products Contraindications and Precautions
COVID-19 Vaccines for Adolescents and Adults Vaccine Safety
Special Populations Storage and Handling
Guidance from CDC about COVID-19 vaccines is evolving rapidly. To ensure access to the most current guidance, Ask the Experts answers often connect our readers directly to vaccine resources provided by the Centers for Disease Control and Prevention (CDC).

For a comprehensive collection of COVID-19 tools and resources, visit IAC's Vaccines: COVID-19 main page: www.immunize.org/covid-19. For alerts about new IAC or CDC COVID-19 resources, subscribe to our weekly newsletter, IAC 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. Adults 65 years and older 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). State and local public health officials are responsible for COVID-19 vaccination program implementation: consult them for details about vaccination policies in their jurisdictions. ACIP has updated its recommendations frequently as new information has emerged since the first vaccine was authorized in December 2020. All ACIP COVID-19 vaccine recommendations can be accessed here: www.cdc.gov/vaccines/hcp/acip-recs/vacc-specific/covid-19.html.
In addition to ACIP recommendations for the use of these vaccines, CDC has published important interim clinical considerations for vaccination of eligible recipients: www.cdc.gov/vaccines/covid-19/clinical-considerations/covid-19-vaccines-us.html
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 12 years and older are recommended to receive an age-appropriate COVID-19 vaccination.
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, as demonstrated in this study published in MMWR: www.cdc.gov/mmwr/volumes/70/wr/pdfs/mm7032e1-H.pdf.
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.
What is the difference between an "additional dose" of COVID-19 vaccine recommended for an immunocompromised person and a "booster dose"?
An additional dose of mRNA vaccine after an initial primary series of mRNA vaccine is recommended by CDC for people with moderate or severe immunocompromise. In these populations, the immune response following the primary 2-dose series is likely to be insufficient, and the additional dose increases the likelihood of developing a sufficient immune response. The additional dose of mRNA vaccine should not be delayed. It may be given 28 days or more after the last dose of the primary series.
The term "booster dose" applies to an additional dose of vaccine administered only after the initial sufficient immune response to the primary series is likely to have waned over time. The interval between a primary series and a booster dose is at least several months.
For details about vaccination of immunocompromised people, see the section on special populations or CDC's interim clinical considerations for the use of COVID-19 vaccines: www.cdc.gov/vaccines/covid-19/clinical-considerations/covid-19-vaccines-us.html#considerations-additional-vaccine-dose.
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.
What does FDA's approval of the biologics licensure application (BLA) for Comirnaty, the Pfizer-BioNTech COVID-19 Vaccine, mean for my clinic?
On August 23, 2021, FDA approved the BLA for Pfizer-BioNTech COVID-19 Vaccine for individuals age 16 years and older; its trade name is Comirnaty. The vaccine remains authorized for emergency use for children age 12 through 15 years and for administration of an additional dose in immunocompromised people. For simplicity, the Ask the Experts COVID-19 section will continue, for now, to refer to Comirnaty as Pfizer-BioNTech COVID-19 Vaccine. No changes have been made to the storage, handling, or vaccine ordering requirements as a result of licensure. Clinicians should continue to administer this vaccine in accordance with current ACIP recommendations and CDC guidelines.
The FDA issued an updated Fact Sheet that reflects the new trade name and combines information for individuals receiving the vaccine in accordance with its licensed indication with information for those receiving the product under the terms of its emergency use authorization (EUA).
All clinics providing the Pfizer-BioNTech COVID-19 Vaccine should use the updated Fact Sheet for all recipients and caregivers: www.fda.gov/media/144414/download.
The Fact Sheet for healthcare providers is here: www.fda.gov/media/144413/download.
The link to the prescribing information (PI) for Comirnaty is here: www.fda.gov/media/151707/download.
When will we have a VIS for the vaccines that have an EUA? 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 no VIS for COVID-19 vaccines authorized under an EUA. On August 23, 2021, FDA issued a revised fact sheet for the Pfizer-BioNTech vaccine (Comirnaty) that covers both its limited licensed indications and its broader emergency use authorization. Once a COVID-19 VIS is issued, the VIS and all available translations will be posted here: https://immunize.org/vis/.
The combined Fact Sheet for all recipients and caregivers about Comirnaty and Pfizer-BioNTech COVID-19 Vaccine is available here: www.fda.gov/media/144414/download.
The Moderna COVID-19 Vaccine EUA Fact Sheet for Recipients and Caregivers is available here: www.fda.gov/media/144638/download.
The Janssen COVID-19 Vaccine EUA Fact Sheet for Recipients and Caregivers is available here: www.fda.gov/media/146305/download.
What are mRNA vaccines?
Both the Pfizer-BioNTech COVID-19 (Comirnaty) 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. 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 do the mRNA COVID-19 vaccines work?
The FDA EUA was issued based upon the short-term effectiveness of these vaccines at preventing symptomatic illness with COVID-19. The preliminary results of large phase 3 clinical trials for both mRNA vaccines were similar, demonstrating an overall efficacy of 94–95% in preventing symptomatic COVID-19 illness compared to placebo recipients. 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. Observational studies of short-term, real world effectiveness are consistent with the clinical trial results. In the months following EUA, vaccine effectiveness against severe disease and hospitalization remains high against known variants, including the Delta variant, even as protection against milder illness may be reduced.
Please describe the Janssen COVID-19 Vaccine (Johnson & Johnson).
On February 27, 2021, the FDA issued an Emergency Use Authorization (EUA) for the Janssen COVID-19 (Ad.26.COV2.S) 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. Vaccination with the Janssen vaccine consists of a single dose (5 1010 virus particles per 0.5-mL dose) administered intramuscularly. The Janssen vaccine has been associated with a rare immune-mediated blood clotting disorder; see the vaccine safety section for additional information.
How well does the Janssen COVID-19 Vaccine work?
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 remains high against known variants, including the Delta variant, even as protection against milder illness may be reduced.
How well do COVID-19 vaccines work to prevent asymptomatic infection with SARS-CoV-2? Based on that, what can be said about what people may do after they are fully vaccinated?
A growing body of evidence suggests that fully vaccinated people are less likely than the unvaccinated to have asymptomatic infection or transmit SARS-CoV-2 to others; however, the degree of protection may vary depending on the variant of the virus to which a person is exposed and the time since vaccination. How long vaccine protection lasts and to what degree vaccines protect against emerging SARS-CoV-2 variants are under ongoing investigation. CDC guidelines 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 immunization providers need to know.
Pfizer-BioNTech COVID-19 Vaccine (Comirnaty): 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.
In addition to CDC, each company has a detailed Fact Sheet for Providers.
Pfizer-BioNTech COVID-19 Vaccine (combines information for licensed use and EUA): www.fda.gov/media/144413/download
  Moderna COVID-19 Vaccine: www.fda.gov/media/144637/download
  Janssen COVID-19 Vaccine: www.fda.gov/media/146304/download
COVID-19 Vaccines for Adolescents and Adults Back to top
What ages are authorized to receive the available COVID-19 vaccines?
On May 10, 2021, FDA authorized the Pfizer-BioNTech COVID-19 vaccine for emergency use in people age 12 years and older; it is licensed for ages 16 years and older. Moderna and Janssen COVID-19 vaccines are authorized for emergency use in people age 18 years and older. Further FDA authorization of one or more of the vaccines in younger age groups could occur once sufficient data are generated to support an application.
What do we know about the Pfizer-BioNTech COVID 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 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 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.
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 continuing 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 age 12 years and older, including 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. They can be administered any authorized vaccine: ACIP does not state a product preference. However, women younger than age 50 years should be aware of the rare risk of blood clots with low platelet counts (thrombosis with thrombocytopenia syndrome [TTS]) after receipt of the Janssen vaccine and the availability of other FDA-authorized or licensed COVID-19 vaccines (mRNA vaccines) that do not have that risk.
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 all people age 12 years and older, including people who are lactating. Lactating women younger than age 50 should be aware of the increased risk for TTS with the Janssen vaccine and the availability of other FDA-authorized or licensed COVID-19 vaccines (i.e., mRNA vaccines).
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 mRNA and non-replicating viral vector 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.
Why is an additional dose of mRNA vaccine recommended for some immunocompromised people?
Immunocompromised people are at increased risk for severe COVID-19 illness. Studies have shown a reduced immune response to COVID-19 vaccines in some people with immunocompromising conditions or people who take immunosuppressive medications. Small studies have shown that an additional mRNA vaccine dose in some immunocompromised people who had already completed the primary mRNA vaccine series increased the proportion of people who showed an antibody response to vaccination, which may mean they are better protected from illness. Side effects were similar to the side effects of prior doses.
Although the benefit of the additional dose of mRNA vaccine for a moderately or severely immunocompromised person is not precisely known, the available evidence of potential benefit and acceptable safety supports its use.
Immunocompromised people who receive an additional dose should be counseled that they may still have a reduced immune response to COVID-19 vaccination, even after an additional dose. 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.
Exactly which immunocompromised groups are recommended to receive an additional dose of mRNA vaccine?
The age groups eligible are those already eligible for mRNA vaccines: people age 12 years or older (Pfizer-BioNTech) and people age 18 years or older (Moderna).
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 COVID-19 vaccines: www.cdc.gov/vaccines/covid-19/clinical-considerations/covid-19-vaccines-us.html#considerations-additional-vaccine-dose.
Should I conduct serologic testing or cellular immune testing before or after offering an additional dose of mRNA vaccine to an immunocompromised patient?
No. At this time, serologic testing or cellular immune testing before or after an additional 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 dose?
CDC recommends that the additional dose should be the same brand as the primary series. However, if the same brand is unavailable, you may administer the other mRNA vaccine. An immunocompromised person should not receive more than 3 mRNA vaccine doses.
My patient takes high dose steroids and received a single dose of Janssen COVID-19 Vaccine (Johnson & Johnson) in late March 2021. He meets the definition of moderate or severe immunocompromise. Should I give him an additional dose of Janssen or mRNA vaccine?
At this time, there are insufficient data to recommend an additional dose either of mRNA vaccine or Janssen vaccine for immunocompromised patients who received primary COVID-19 vaccination with Janssen vaccine. Additional guidance from FDA and CDC is expected once data are available.
My patient has had a kidney transplant and wants to know if he is considered fully vaccinated for public health purposes (e.g., allowed to enter a restaurant where proof of immunization is required) if he has received the 2-dose mRNA primary series but has not yet had an additional dose?
Yes. CDC guidance states that, for the purposes of public health classification, all vaccinated individuals may be classified as fully vaccinated beginning 2 weeks after receipt of either a single dose of Janssen vaccine or a two-dose primary series of mRNA vaccine. A person known to be immunocompromised is not required to receive a third mRNA dose to be considered fully vaccinated. However, he should be counseled to continue to practice preventive measures, such as wearing a mask and avoiding crowds, even after an additional dose, to limit his risk of exposure to SARS-CoV-2.
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:
Pfizer-BioNTech COVID-19 Vaccine (Comirnaty): www.cdc.gov/vaccines/covid-19/info-by-product/pfizer/downloads/prep-and-admin-summary.pdf
  Moderna COVID-19 Vaccine: www.cdc.gov/vaccines/covid-19/info-by-product/moderna/downloads/prep-and-admin-summary.pdf
  Janssen COVID-19 Vaccine: 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 Use of COVID-19 Vaccines Currently Authorized in the United States." This appendix provides resources for preventing and reporting COVID-19 vaccine administration errors, and a simple table outlining actions to take after an error has occurred: www.cdc.gov/vaccines/covid-19/clinical-considerations/covid-19-vaccines-us.html#Appendix-A.
The summary table is also available from CDC as a print-ready document: www.cdc.gov/vaccines/covid-19/downloads/covid19-vaccine-errors-deviations.pdf.
Errors addressed include the following:
Incorrect route or site
  Incorrect age
  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 vaccine
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?
For detailed information on COVID-19 vaccine scheduling, refer to the CDC's interim clinical considerations for COVID-19 vaccination: www.cdc.gov/vaccines/covid-19/info-by-product/clinical-considerations.html.
What is the recommended schedule for mRNA COVID-19 vaccines?
The Pfizer-BioNTech COVID-19 Vaccine (Comirnaty) primary series is administered as a two-dose series, 21 days apart. Both doses should be the Pfizer-BioNTech vaccine.
The Moderna COVID-19 Vaccine primary series is administered as a two-dose series, 28 days apart. Both doses should be the Moderna vaccine.
Second doses of either mRNA vaccine may be scheduled routinely up to 6 weeks after the first dose, if desired, but should not be scheduled earlier than the recommended interval.
Every effort should be made to administer the same brand for both doses. There are no data on the effectiveness of a mixed-brand vaccination series. In exceptional situations in which the first-dose vaccine product cannot be determined or is no longer available, any available mRNA COVID-19 vaccine may be administered at a minimum interval of 28 days between doses to complete the mRNA COVID-19 vaccination series. If two doses of different mRNA COVID-19 vaccine products are administered in these situations (or inadvertently), no additional doses of either product are recommended at this time.
If no mRNA vaccine is obtainable for the second dose, a single dose of the Janssen vaccine may be administered at least 28 days after the mRNA vaccine dose. The recipient should be considered to have received a valid, single-dose Janssen vaccination—not a mixed vaccination series.
Individuals with moderate or severe immunocompromise who complete a two-dose primary series of either mRNA vaccine are recommended to receive an additional dose of mRNA vaccine, preferably of the same brand, at least 28 days after completing the primary series.
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. Simply administer the second dose to complete the series.
What if the patient gets the second dose of an mRNA COVID-19 vaccine early?
Second doses administered within a grace period of 4 days or fewer from the recommended date for the second dose are considered valid; however, doses administered earlier do 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 mRNA vaccine as a second dose, does it need to be repeated with the correct brand?
If a recipient is inadvertently given a different brand of mRNA vaccine for the second dose, the CDC does not currently recommend that the patient receive a repeat dose of either product.
If a patient received a dose of mRNA COVID-19 vaccine, but cannot obtain a second dose of the original brand of mRNA vaccine, what should we do?
Once a series is initiated, the first choice is to complete the mRNA COVID-19 vaccine series with the same brand. In exceptional circumstances where the same brand cannot be obtained, the series may be completed with a different mRNA brand.
Only in situations where no second dose of mRNA COVID-19 vaccine may be given (due to availability or contraindication), a single dose of Janssen COVID-19 vaccine may be considered at a minimum interval of 28 days from the mRNA COVID-19 vaccine dose. Patients who receive the Janssen COVID-19 vaccine after a dose of an mRNA COVID-19 vaccine should be considered to have received a valid, single-dose Janssen vaccination—not a mixed vaccination series.
We have a patient who was fully vaccinated with a COVID-19 vaccine not authorized in the U.S. Do we need to revaccinate?
Not necessarily. People who completed a COVID-19 vaccination series with a vaccine that has been authorized for emergency use by the World Health Organization (WHO) do not need any additional doses with an FDA-authorized COVID-19 vaccine. People who completed or partially completed a COVID-19 vaccine series with a vaccine that is not authorized by either FDA or WHO may be offered an FDA-authorized COVID-19 vaccine series. The minimum interval between the last dose of a non-FDA authorized vaccine and an FDA-authorized COVID-19 vaccine is 28 days.
As of August 13, 2021, WHO has listed the following vaccines for emergency use:
Pfizer-BioNTech COVID-19 vaccines (also known as Comirnaty, tozinameran)
  AstraZeneca-Oxford COVID-19 vaccines (also known as ChAdOx1-S, Covishield, Vaxzevria)
  Janssen (Johnson & Johnson) COVID-19 Vaccine
  Moderna COVID-19 Vaccine (also known as Spikevax)
  Sinopharm COVID-19 Vaccine (also known as BBIBP-CorV)
  Sinovac COVID-19 Vaccine (also known as CoronaVac)
We have a patient who was partially vaccinated with a COVID-19 vaccine not authorized for use in the U.S. What should we do?
People who are partially vaccinated outside the U.S. with a COVID-19 vaccine brand not authorized in the U.S. may be offered a complete FDA-authorized or licensed COVID-19 vaccine series. The minimum interval between the last dose of a non-FDA authorized vaccine and an FDA-authorized or licensed COVID-19 vaccine is 28 days.
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.
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. COVID-19 vaccines and other vaccines may be administered without regard to timing.
COVID-19 vaccines were previously recommended to be administered alone, with a minimum interval of 14 days before or after administration of any other vaccines. This was out of an abundance of caution and not due to any known safety concerns or concerns about interference with effectiveness. Although data are not available for COVID-19 vaccines administered simultaneously with other vaccines, 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.
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 of COVID-19 vaccine or other vaccines are 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.
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?
COVID-19 vaccination may take place on the same day or any day after a TST is placed. A TST will not interfere with the response to vaccination. The reliability of a TST is expected to be unchanged if a TST is placed before or simultaneously with COVID-19 vaccination. The reliability of a negative TST or interferon gamma release assay (IGRA) soon after COVID-19 vaccination has not been studied.
COVID-19 vaccination should not be delayed because of testing for tuberculosis (TB) infection. A TST is not a vaccine. If not administered on the same day, CDC recommends that a TST be delayed at least 4 weeks after completion of COVID-19 vaccination because the reliability of a negative TST result soon after COVID-19 vaccination is unknown.
For additional details on COVID-19 vaccination of patients being evaluated for active tuberculosis, please refer to CDC clinical considerations for COVID-19 vaccines and laboratory testing: www.cdc.gov/vaccines/covid-19/clinical-considerations/covid-19-vaccines-us.html#laboratory-testing.
How does the use of monoclonal antibodies to treat symptomatic COVID-19 affect the scheduling of COVID-19 vaccination?
There are no data on the effect of passive antibody therapies for COVID-19, including monoclonal antibodies and convalescent plasma, on the effectiveness of vaccination with COVID-19 vaccines. As a precautionary measure, CDC recommends waiting at least 90 days after receipt of passive antibody therapy for COVID-19 illness before initiating the COVID-19 vaccine series. Individuals who develop COVID-19 illness after the first COVID-19 vaccination and receive passive antibody therapy should wait 90 days after antibody therapy to receive the second dose. There is no need to restart the vaccination series.
Antibody therapies not specific to COVID-19 treatment (e.g., intravenous immunoglobulin, RhoGAM) are unlikely to substantially impair development of a protective antibody response to COVID-19 vaccination. Thus, there is no recommended minimum interval between antibody therapies not specific to COVID-19 treatment and any COVID-19 vaccination.
Contraindications and Precautions Back to top
Please describe the contraindications for each COVID-19 vaccination.
CDC considers a history of the following to be a contraindication to vaccination with COVID-19 vaccines:
Severe allergic reaction (e.g., anaphylaxis) after a previous dose or to a component of the COVID-19 vaccine
  Immediate allergic reaction of any severity to a previous dose or known (diagnosed) allergy to a component of the vaccine
Polyethylene glycol (PEG) is an ingredient in both mRNA COVID-19 vaccines, and polysorbate 80 is an ingredient in Janssen COVID-19 vaccine. PEG and polysorbate are structurally related, and cross-reactive hypersensitivity between these compounds may occur. People with a contraindication to one of the mRNA COVID-19 vaccines should not receive doses of either of the mRNA vaccines (Pfizer-BioNTech or Moderna). However, people with a contraindication to mRNA COVID-19 vaccines may be able to receive Janssen vaccine, and vice versa (see description of COVID-19 vaccine precautions for details). Known polysorbate allergy is no longer a contraindication to mRNA vaccination; however, known polysorbate allergy is a contraindication to Janssen vaccine and thus, a precaution to mRNA COVID-19 vaccination.
A list of ingredients in each COVID-19 vaccine is available here: www.cdc.gov/vaccines/covid-19/clinical-considerations/covid-19-vaccines-us.html#Appendix-C.
CDC has provided a chart to assist in the evaluation of immediate reactions to vaccination: www.cdc.gov/vaccines/covid-19/clinical-considerations/covid-19-vaccines-us.html#Appendix-D.
What are the precautions to COVID-19 vaccination?
CDC considers a history of an immediate allergic reaction to any other vaccine or injectable therapy (i.e., intramuscular, intravenous, or subcutaneous vaccines or therapies [excluding subcutaneous immunotherapy for allergies, i.e., "allergy shots"]) as a precaution but not a contraindication to vaccination. People with a reaction to a vaccine or injectable therapy that contains multiple components, one of which is a vaccine component, but in whom it is unknown which component elicited the immediate allergic reaction, have a precaution to vaccination.
People with a contraindication to one type of the currently authorized or licensed COVID-19 vaccines (e.g., mRNA) have a precaution to the other (e.g., Janssen viral vector). However, because of potential cross-reactive hypersensitivity between ingredients in mRNA and Janssen COVID-19 vaccines, consultation with an allergist-immunologist should be considered to help determine if the patient can safely receive vaccination. Healthcare providers and health departments may also request a consultation from the Clinical Immunization Safety Assessment COVIDvax project (www.cdc.gov/vaccinesafety/ensuringsafety/monitoring/cisa/index.html). Vaccination of these individuals should only be undertaken in an appropriate setting under the supervision of a health care provider experienced in the management of severe allergic reactions.
People with a contraindication to mRNA COVID-19 vaccines (including due to a known PEG allergy) may consider vaccination with Janssen COVID-19 Vaccine. People who have received one mRNA COVID-19 vaccine dose but for whom the second dose is contraindicated should wait at least 28 days after the mRNA vaccine dose to receive Janssen COVID-19 Vaccine.
People with a contraindication to Janssen COVID-19 Vaccine (including due to a known polysorbate allergy) may consider mRNA COVID-19 vaccination. Polysorbate allergy is no longer a contraindication to mRNA COVID-19 vaccination, it is a precaution.
The following considerations can be used to conduct a risk assessment for vaccination in individuals with a precaution to vaccination:
Risk of exposure to SARS-CoV-2
  Risk of severe disease or death due to COVID-19
  The unknown risk of anaphylaxis following COVID-19 vaccination in a person with a history of an immediate allergic reaction to other vaccines or injectable therapies
  Ability of the recipient to be vaccinated in a setting where appropriate medical care is immediately available for anaphylaxis. Note, for people with a contraindication to one type of COVID-19 vaccine (e.g., mRNA vaccines), vaccination with another type (e.g., Janssen viral vector vaccine) should only be undertaken in an appropriate setting under the supervision of a health care provider experienced in the management of severe allergic reactions.
For additional guidance about contraindications and precautions, please refer to www.cdc.gov/vaccines/covid-19/clinical-considerations/covid-19-vaccines-us.html#Contraindications.
Can people who are immunocompromised or who have autoimmune disease be vaccinated with mRNA 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.
People should be counseled about the unknown vaccine safety profile and effectiveness in immunocompromised populations and the potential for reduced immune responses. Individuals with moderate or severe immunocompromise who have received a primary series of mRNA vaccine are recommended to receive an additional dose of mRNA vaccine at least 28 days after the primary series. Please see detailed considerations about administration of an additional dose here: www.cdc.gov/vaccines/covid-19/clinical-considerations/covid-19-vaccines-us.html#considerations-additional-vaccine-dose.
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 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?
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. Some people have reported delayed-onset local reactions, including Moderna clinical trial participants, beginning a few days through the second week after the first dose. The 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 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)?
No. The rare syndrome that combines thrombosis (blood clot) and thrombocytopenia (low platelet count), known as TTS, that is associated with the Janssen COVID-19 Vaccine appears to be similar to another rare immune-mediated syndrome, heparin-induced thrombocytopenia (HIT). Until more information becomes available, experts advise that individuals with a history of an episode of an immune-mediated TTS, such as HIT, should be offered another FDA-authorized or licensed COVID-19 vaccine (i.e., mRNA vaccine) if they are within at least 90 days after resolution of their TTS illness. After 90 days, patients may be vaccinated with any FDA-authorized or licensed COVID-19 vaccine.
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. These people can receive any FDA-authorized or licensed vaccine, including the Janssen vaccine.
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)?
Currently, there are no data on the safety and efficacy of COVID-19 vaccines in people with a history of multisystem inflammatory syndrome in children (MIS-C) or in adults (MIS-A) after SARS-CoV-2 infection. The mechanisms of MIS-C and MIS-A are not well understood but include a dysregulated immune response to SARS-CoV-2 infection. It is unclear if people with a history of MIS-C or MIS-A are at risk of recurrence of the same dysregulated immune response following reinfection with SARS-CoV-2 or in response to vaccination.
People with a history of MIS-C or MIS-A may choose to be vaccinated. Considerations for vaccination may include:
Clinical recovery from MIS-C or MIS-A, including return to normal cardiac function
  Personal risk of severe acute COVID-19
  Level of COVID-19 community transmission and personal risk of reinfection
  Lack of safety data of COVID-19 vaccines following these illnesses
  Timing of any immunomodulatory therapies
Though not required before vaccination, a conversation between the patient, their guardian(s), and their clinical team or a specialist may assist with decisions about the use of a COVID-19 vaccine.
People with a history of MIS-C or MIS-A should consider delaying vaccination until they have recovered from their illness and for 90 days after the date of diagnosis of MIS-C or MIS-A, because the risk of SARS-CoV-2 reinfection (and benefit of vaccination) may increase with time following initial infection.
My patient had an episode of myocarditis 5 years ago. Is a history of myocarditis a contraindication or precaution to vaccination with an mRNA vaccine?
People who have a history of myocarditis or pericarditis unrelated to mRNA COVID-19 vaccination may receive any currently FDA-authorized or licensed COVID-19 vaccine after the episode of myocarditis or pericarditis has completely resolved. This includes resolution of symptoms attributed to myocarditis or pericarditis, as well as no evidence of ongoing heart inflammation or damage as determined by the person's clinical team.
Individuals who experience myocarditis or pericarditis after their first mRNA vaccination are advised to defer receiving the second dose until additional safety data are available. If such a person elects to receive a second dose, they should wait until their episode of myocarditis or pericarditis has fully resolved and make the decision in consultation with their clinical team.
For additional details, see CDC's interim clinical considerations for COVID-19 vaccination of people with certain underlying health conditions: www.cdc.gov/vaccines/covid-19/clinical-considerations/covid-19-vaccines-us.html#underlying-conditions.
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. However, given the possible association between the Janssen COVID-19 Vaccine and an increased risk of GBS, a patient with a history of GBS and their healthcare provider should discuss the availability of mRNA COVID-19 vaccines to offer protection against COVID-19.
Vaccine Safety Back to top
What 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.
What 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.
On April 13, 2021, after 6 reports of TTS to VAERS, the FDA and CDC recommended a pause in the use of the Janssen vaccine while a thorough safety investigation was conducted. This pause also allowed healthcare professionals to be informed how to recognize, diagnose, treat, and report suspected cases of TTS. On April 23, 2021, based on its conclusion that the risk of severe COVID-19 disease substantially outweighed the rare risk of TTS, ACIP reaffirmed its interim recommendation for use of the Janssen vaccine in all people age 18 years and older under the FDA EUA.
The highest rates of TTS were identified by CDC in women younger than age 50 years. At the time the pause was lifted, the rate was 7 cases per million Janssen vaccine doses administered to women age 18–49 years and 0.9 per million to women age 50 years and older.
The FDA's EUA fact sheets now include a warning that rare TTS might occur after vaccination, primarily among women age 18–49 years. It is critical to ensure that women younger than age 50 years are aware of the increased risk for TTS after receipt of the Janssen vaccine and the availability of other FDA-authorized or licensed COVID-19 vaccines (i.e., mRNA vaccines) not associated with TTS.
What are the symptoms of TTS and where can I learn more about treatment?
TTS following vaccination with the Janssen COVID-19 Vaccine is rare, but the risk is increased among women younger than age 50 years. 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)?
Reports to the Vaccine Adverse Event Reporting System (VAERS) following use of Janssen COVID-19 Vaccine indicate an increased risk of GBS within 42 days of vaccination. Investigations to assess whether Janssen vaccine causes GBS are ongoing. Although the chance of GBS occurring is 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.
Patients with a history of GBS may receive Janssen COVID-19 Vaccine, but should be counseled about the potential increased risk of GBS and the availability of alternative vaccine options for COVID-19 protection.
I have both mRNA and Janssen vaccines available. Should I avoid offering the Janssen COVID-19 Vaccine to my younger female patients?
All who prefer the Janssen vaccine may be offered that option, if available. It is critical that all women younger than age 50 be made aware of the rare, but increased, risk of TTS following Janssen vaccine administration and the availability of other COVID-19 vaccines not associated with TTS. However, the ACIP has concluded that the risks of delaying full immunization while the virus that causes COVID-19 is circulating widely substantially outweigh the risk of TTS. Completing vaccination with a single dose is an advantage, and a priority, for some recipients.
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.
Reports of myocarditis (inflammation of the heart muscle) and pericarditis (inflammation of the tissue surrounding the heart) within a few days of mRNA COVID-19 vaccination have prompted the FDA to include information about these conditions in the Fact Sheets for each mRNA vaccine. There has not been a similar reporting pattern observed after receipt of Janssen COVID-19 Vaccine.
ACIP conducted a risk assessment and observed that the reported risk was rare, but was most commonly reported in males age 12 through 29; reported cases have occurred more often after dose 2 than dose 1. In most cases, patients who were diagnosed with myocarditis or pericarditis after mRNA vaccination have responded well to medication and rest and had prompt improvement of symptoms. ACIP has concluded that the benefit of vaccination clearly outweighs the risk of myocarditis or pericarditis.
People receiving mRNA vaccines, especially males age 12 through 29, 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.
CDC has published additional clinical considerations for 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 Janssen viral vector vaccine may not be contraindicated (see the COVID-19 section on contraindications and precautions for details). Please see this CDC chart of vaccine components designed to assist the triage of patients with various health conditions or allergies: www.cdc.gov/vaccines/covid-19/clinical-considerations/covid-19-vaccines-us.html#Appendix-C.
How long should patients be observed for signs of an immediate allergic reaction following vaccination with a COVID-19 vaccine?
People with a history of an immediate allergic reaction of any severity to a vaccine or injectable therapy and people with a history of anaphylaxis due to any cause should be observed for 30 minutes. People with a contraindication to a different type of COVID-19 vaccine should be observed for 30 minutes following vaccination (for example, people with a contraindication to mRNA COVID-19 vaccines who receive Janssen viral vector vaccine should be observed for 30 minutes following Janssen vaccination). All other people should be observed for 15 minutes.
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.
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:
Vaccine administration errors
  Serious adverse events, including TTS
  Cases of Multisystem Inflammatory Syndrome
  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.
IAC 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.
I heard the Pfizer-BioNTech vaccine storage requirements changed in May 2021. Where can I get more information?
In May 2021, the FDA authorized storage of the Pfizer-BioNTech vaccine at refrigerated temperatures, between 2C and 8C (36F and 46F), for up to 1 month (31 days). It is permissible to store the vaccine in a standard freezer between -25C and -15C (-13F to 5F) for up to 2 weeks before storing in the refrigerator for up to 31 days. No changes to these specifications were made at the time of licensure on August 23, 2021. Detailed storage and handling information is available from CDC in a printable document: www.cdc.gov/vaccines/covid-19/info-by-product/pfizer/downloads/storage-summary.pdf.
Pfizer-BioNTech vaccine (Comirnaty) stored in an ultra-low temperature freezer (ULT, between -80C and -60C [-112F and -76F]) may have its expiration date extended as more data become available on the vaccine's stability under those storage conditions. Contact the manufacturer before discarding any vaccine past its printed expiration date to verify that its expiration date has not been extended.
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, if possible, or to initiate transport while they are frozen. Moderna recommends that thawed vials of liquid be cushioned to minimize agitation during transport. Thawed vaccine should never be refrozen. 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 2021 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 on page 11 of 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 23, 2021.
This page was reviewed on August 23, 2021.
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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.