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Ask the Experts: COVID-19

The COVID-19 questions were last reviewed on November 16, 2025. See CDC’s Use of COVID-19 Vaccines in the United States Interim Clinical Considerations for more information. To keep up with the current available COVID-19 resources from CDC, FDA, and Immunize.org, see Immunize.org’s Checklist of Current Versions of U.S. COVID-19 Vaccine Guidance and Clinic Support Tools, updated at least monthly. For alerts about new Immunize.org or CDC COVID-19 resources, subscribe to our weekly e-newsletter, IZ Express.

Results (92)

Your patient may choose to receive the vaccines at the same visit or separately, without regard to the timing interval.

When multiple vaccines are administered at a single visit, administer each injection in a different syringe and at 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. However, 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.

Last reviewed: October 18, 2026

CDC does not recommend delaying COVID-19 vaccination because a person received monoclonal antibodies or convalescent plasma. However, the order matters for pemivibart (Pemgarda), a monoclonal antibody product used for pre-exposure prophylaxis: CDC states that, under the FDA EUA, pemivibart should be given at least 2 weeks after a COVID-19 vaccine dose. Pemivibart is not a substitute for vaccination. See www.cdc.gov/covid/hcp/vaccine-considerations/immunocompromised.html.

Last reviewed: October 18, 2026

We refer our readers to CDC’s updated set of contraindications and precautions to vaccination with COVID-19 vaccines, located in its interim clinical considerations for the use of COVID-19 vaccines in the United States: www.cdc.gov/covid/hcp/vaccine-considerations/contraindications-precautions.html.

Last reviewed: October 18, 2026

We refer our readers to CDC’s updated set of contraindications and precautions to COVID-19 vaccination, located in its interim clinical considerations for the use of COVID-19 vaccines: www.cdc.gov/covid/hcp/vaccine-considerations/contraindications-precautions.html.

Last reviewed: October 18, 2026

Anaphylaxis occurs at a rate of approximately 5 cases per 1 million mRNA COVID-19 vaccinations administered. CDC considers a history of an anaphylactic reaction to a dose of mRNA COVID-19 vaccine a contraindication to receipt of further doses of mRNA-type COVID-19 vaccines. However, a person with a contraindication to one type of COVID-19 vaccine (mRNA) may receive the alternative COVID-19 vaccine type (in this case, the adjuvanted protein subunit vaccine, Nuvaxovid, if age 12 years or older) in the usual vaccination setting.

CDC offers additional considerations for patients with a history of allergic reactions in its interim clinical considerations: www.cdc.gov/covid/hcp/vaccine-considerations/contraindications-precautions.html

CDC’s Clinical Immunization Safety Assessment (CISA) Project (www.cdc.gov/vaccine-safety-systems/hcp/cisa/) may be an option for a complex COVID-19 vaccine safety question not readily addressed by CDC guidance.

Last reviewed: October 18, 2026

Individuals with only a delayed-onset local reaction (e.g., redness, induration, itching) around the injection site area after an mRNA vaccine dose do not have a contraindication or precaution to subsequent doses. Consider administering the next dose in the opposite arm, if possible.

These delayed-onset local reactions are sometimes quite large but are self-limited. These reactions are not believed to represent an increased risk for anaphylaxis after future doses.

Patients who experience this reaction 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.

Last reviewed: October 18, 2026

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, CDC does not recommend routine administration of such medications before vaccination.

CDC does not recommend antihistamines before COVID-19 vaccination to prevent allergic reactions. Antihistamines do not prevent anaphylaxis, and their use might mask cutaneous symptoms, which could delay diagnosis and management of anaphylaxis.

Last reviewed: October 18, 2026

The COVID-19 vaccines currently available in the United States (mRNA vaccines and the Nuvaxovid adjuvanted protein vaccine) are not contraindicated in patients with a history of TTS. The Janssen COVID-19 vaccine associated with immune-mediated TTS in the United States has not been available in the United States since 2023.

Last reviewed: October 18, 2026

According to CDC, MIS-C and MIS-A both include a dysregulated immune response to SARS-CoV-2 infection. Experts consider the benefits of vaccination to outweigh the theoretical risk of an MIS-like illness or the risk of myocarditis following COVID-19 vaccination in a person with a history of MIS-C or MIS-A if the person meets the following criteria: (1) they have clinically recovered, including return to baseline cardiac function; and (2) it has been at least 90 days since the diagnosis of MIS-C or MIS-A.

There are additional considerations for vaccination of those who do not meet these criteria. Refer to CDC’s detailed guidance for the most current clinical considerations for vaccination of children and adults who have experienced this syndrome following SARS-CoV-2 infection or who have experienced MIS-like illness following COVID-19 vaccination: www.cdc.gov/covid/hcp/vaccine-considerations/special-situations-and-populations.html.

Last reviewed: October 18, 2026

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. “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.

For people who have a history of myocarditis associated with MIS-C or MIS-A following SARS-CoV-2 infection, see CDC’s interim clinical considerations concerning COVID-19 vaccination and MIS-C and MIS-A: www.cdc.gov/covid/hcp/vaccine-considerations/special-situations-and-populations.html.

Complete and current clinical considerations for COVID-19 vaccination of patients with a history of myocarditis are available from CDC here: www.cdc.gov/covid/hcp/vaccine-considerations/safety-considerations.html.

Last reviewed: October 18, 2026

CDC considers development of myocarditis or pericarditis within 3 weeks after a dose of any COVID-19 vaccine a precaution to a subsequent dose of any COVID-19 vaccine, and experts advise that these people should generally not receive a subsequent dose of any COVID-19 vaccine. Under certain conditions, the clinical team may determine that benefits of vaccination outweigh risks, but vaccination should wait until at least their episode of myocarditis or pericarditis has resolved and there is no evidence of ongoing heart inflammation or sequelae. See CDC’s detailed guidance for additional information about these clinical considerations: www.cdc.gov/covid/hcp/vaccine-considerations/safety-considerations.html.

Last reviewed: October 18, 2026

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. 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.

Among children ages 6 months through 4 years pain or tenderness at the injection site was the most frequent local reaction noted in clinical trials. 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.

Last reviewed: October 18, 2026

In clinical trials of the COVID-19 adjuvanted protein vaccine, known commercially as Nuvaxovid (Sanofi-Novavax), 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.

Last reviewed: October 18, 2026

Vaccinating people against influenza who have recently tested positive for COVID-19 involves multiple considerations, such as whether vaccinating them could expose others to COVID-19, how sick they are, their risk for severe influenza illness, the ability to vaccinate at a later date, and the desire to avoid confusing postvaccination symptoms with those of COVID-19. Usually, people who are known to be infectious should not be brought to a vaccination setting if doing so could expose others to COVID-19. Any moderate or severe acute illness is a precaution to influenza vaccination: vaccination should generally be deferred until recovery. For people with mild or asymptomatic COVID-19, delaying vaccination also might be considered to avoid confusing COVID-19 symptoms with postvaccination reactions.

Last reviewed: October 18, 2026

Yes. CDC’s contraindications and precautions do not preclude giving an age-appropriate current COVID-19 vaccine to individuals with a history of GBS.

Last reviewed: October 18, 2026

There is no evidence that any of the COVID-19 vaccines affect current or future fertility.

Last reviewed: October 18, 2026


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Last reviewed: May 26, 2023

There is an extremely rare risk of myocarditis (inflammation of the heart muscle) and/or pericarditis (inflammation of the tissue surrounding the heart) following receipt of any COVID-19 vaccine. This rare risk is greatest in biological males age 12 through 39 years. The balance of benefit and risk depends on age, sex, underlying conditions, prior infection and vaccination, and the vaccine schedule. COVID-19 itself is more likely to cause myocarditis and other cardiac complications.

The risk after vaccination appears related to age (12 through 39 years), biological sex (male), and the short (3- to 4-week) interval between initial series doses. Under CDC’s 2026–2027 schedule, an initial series is not recommended except in infants and toddlers younger than age 2 years or in people with moderate or severe immunocompromise. CDC states that extending the interval between the first and second doses to 8 weeks in children age 6 through 23 months who are not moderately or severely immunocompromised might reduce the extremely rare risk of myocarditis following the second dose in this age group; however, this is not recommended if delaying vaccination poses an unacceptable risk of severe COVID-19 illness.

Most patients diagnosed with myocarditis after mRNA COVID-19 vaccination have been hospitalized for short periods, with most experiencing resolution of acute symptoms by hospital discharge. CDC continues to assess long-term outcomes in people with myocarditis after mRNA COVID-19 vaccination.

CDC recommends that people who receive COVID-19 vaccines, especially males age 12 through 39, 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 the adjuvanted protein subunit COVID-19 vaccine (now with brand-name Nuvaxovid) and have also been reported during post-authorization use outside the United States.

CDC’s complete interim clinical considerations for COVID-19 vaccination and myocarditis or pericarditis are available here: www.cdc.gov/covid/hcp/vaccine-considerations/safety-considerations.html.

Last reviewed: October 18, 2026

Serious allergic reactions, such as anaphylaxis, in the minutes following vaccination are rare but are possible with any vaccine. CDC recommends that every vaccination site (regardless of vaccines being given) have staff available who are trained and equipped to recognize and respond to signs of anaphylaxis in a vaccine recipient.

Anaphylaxis following vaccination with mRNA COVID-19 vaccines is reported at a rate of approximately 5 cases per million doses administered.

An immediate severe allergic reaction to any component or previous dose of one COVID-19 vaccine type (the two types are mRNA or protein subunit) is a contraindication to vaccination with that type; however, CDC permits use of the alternate vaccine type for age-eligible patients in the usual vaccination setting, provided there is no additional contraindication to that product. CDC encourages consultation with an allergist-immunologist. See CDC’s COVID-19 interim clinical considerations section on contraindications and precautions for details: www.cdc.gov/covid/hcp/vaccine-considerations/contraindications-precautions.html.

Last reviewed: October 18, 2026

CDC routinely recommends considering observation for 15 minutes after vaccination for syncope (fainting) or development of an immediate allergic reaction.

If you vaccinate a person who has an allergy-related precaution with the same COVID-19 vaccine type associated with that precaution, CDC recommends considering a 30-minute observation period and referral to an allergist-immunologist. CDC permits use of the alternate vaccine type in the usual vaccination setting. See www.cdc.gov/covid/hcp/vaccine-considerations/contraindications-precautions.html.

Last reviewed: October 18, 2026

For all licensed COVID-19 vaccines (Moderna [mNexspike, Spikevax], Sanofi-Novavax [Nuvaxovid], Pfizer-BioNTech [Comirnaty]) CDC encourages healthcare providers to report to the Vaccine Adverse Event Reporting System (VAERS) the following:

  • Any adverse event that occurs after the administration of a vaccine licensed in the United States, whether or not it is clear that a vaccine caused the adverse event
  • Vaccine administration errors, whether or not associated with an adverse event

Information on how to submit a report to VAERS is available at https://vaers.hhs.gov or by calling 1-800-822-7967.

Last reviewed: October 18, 2026

Multiple national surveillance systems are used to monitor the safety of COVID-19 vaccines in different ways. CDC provides information about vaccine safety surveillance systems, with links to information about the safety of COVID-19 vaccines, here: www.cdc.gov/vaccine-safety/vaccines/covid-19.html.

Last reviewed: October 18, 2026

V-safe is a safety monitoring system that vaccine recipients can use to share with CDC how they feel after vaccination. It was created initially for COVID-19 vaccines. Currently, recipients of RSV vaccines also may register for V-safe. To learn more about the program and how to guide vaccine recipients who wish to participate, visit CDC’s website: www.cdc.gov/vaccine-safety-systems/v-safe/index.html.

Last reviewed: October 18, 2026

No. COVID-19 vaccines are not currently part of the VICP. The COVID-19 vaccines are currently part of a similar program called the Countermeasures Injury Compensation Program (CICP). For more information, visit this web page: www.hrsa.gov/cicp.

Last reviewed: October 18, 2026

For the 2026–2027 season, Comirnaty manufacturer-filled syringes (MFS), mNexspike MFS, and Nuvaxovid MFS all should be stored exclusively in the refrigerator at standard vaccine storage temperatures (between 2°C and 8°C [36°F and 46°F]) until the printed expiration date.

Spikevax MFS, if received frozen and never thawed, may be stored at ordinary vaccine freezer storage temperatures (between -50°C and -15°C [-58°F and 5°F]) until the printed expiration date. Once thawed, it may be stored at standard vaccine refrigerator temperatures (above) for up to 60 days or until the expiration date (whichever comes first).

Comirnaty single dose vials (SDV) for ages 6 months through 11 years, if received frozen and never thawed, may be maintained until the printed expiration date in an ultracold freezer between -90°C and -60°C (-130°F and -76°F). Once thawed, it may be stored at standard vaccine refrigerator temperatures (above) for up to 10 weeks, or until the expiration date, whichever comes first.

For further details, refer to the specific vaccine’s package insert. Immunize.org has assembled links to key COVID-19 vaccine resources, including package inserts, in the Checklist of Current Versions of U.S. COVID-19 Vaccination Guidance and Clinic Support Tools: www.immunize.org/catg.d/p3130.pdf.

Last reviewed: October 18, 2026

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 unopened vials or manufacturer-filled syringes (MFS) and always with a continuous temperature monitoring device to ensure adherence to authorized storage times and temperatures. See the product package insert for details on permissible conditions for transport.

Last reviewed: October 18, 2026

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