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.

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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 spreads mainly from person to person through respiratory droplets and small particles produced when an infected person coughs, sneezes, or talks. The virus spreads easily in crowded or poorly ventilated indoor settings. 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 potentially infectious up to 48 hours before symptom onset and up to 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.

Last reviewed: November 16, 2025

The list of underlying health conditions and other factors shown to increase the risk of severe COVID-19 illness is long. Advanced age remains the strongest risk factor. In addition to age, CDC states that data has shown that compared to non-Hispanic White people, people from racial and ethnic minority groups are more likely to be infected with SARS-CoV-2. Once infected, people from racial and ethnic minority groups are more likely to be hospitalized, be admitted to the ICU, and die from COVID-19 at younger ages. CDC provides a list of at-risk conditions at this website: www.cdc.gov/covid/hcp/clinical-care/underlying-conditions.html. The conditions are stratified by strength of published evidence.

Immunize.org provides an age-appropriate list of high-risk conditions with conclusive or suggestive published evidence as part of each of its standing orders templates for use of 2025-2026 COVID-19 vaccines, all of which may be found on the COVID-19 main page: www.immunize.org/vaccines/a-z/covid-19/.

Last reviewed: November 16, 2025

The CDC has assembled clinical information about COVID-19 at this site: www.cdc.gov/covid/hcp.

Last reviewed: November 16, 2025

CDC maintains a webpage with critical interim clinical considerations for vaccination of eligible recipients: www.cdc.gov/covid/hcp/vaccine-considerations/index.html. This covers important clinical details about COVID-19 vaccination. It is typically the first content to be updated after an announced change to CDC recommendations.

All of the CDC’s Advisory Committee on Immunization Practices (ACIP) vaccine recommendations published in MMWR can be accessed here: www.cdc.gov/acip-recs/hcp/vaccine-specific/covid-19.html.

CDC posts product-specific resources at this site: www.cdc.gov/vaccines/covid-19/info-by-product/index.html. At this writing, the website was last updated July 18, 2025.

Last reviewed: November 16, 2025

ACIP recommended on September 18, 2025 that all people age 6 months and older in the United States may receive one or more doses of an age-appropriate 2025–2026 Formula COVID-19 vaccination based on individual decision-making, following shared clinical decision-making discussion with a healthcare professional (e.g., a nurse, doctor, or pharmacist). The decision to vaccinate may be influenced by the presence of conditions that increase the risk of severe COVID-19 illness.

Product options include three FDA-licensed mRNA vaccines: Comirnaty (Pfizer-BioNTech, ages 5 years and older); Spikevax (Moderna, ages 6 months and older); mNexspike (Moderna, ages 12 years and older). There is one FDA-licensed adjuvanted protein subunit vaccine: Nuvaxovid (Sanofi-Novavax, ages 12 years and older). Schedules vary by age and immunocompromised status.

Although the FDA licenses limit use of COVID-19 vaccines among recipients younger than age 64 to those with one or more conditions that increases the risk of severe COVID-19, the fact that ACIP did not include any restrictions in its shared clinical decision-making recommendation means that it is an acceptable standard of care for people younger than age 65 without a high risk condition to be vaccinated when desired.

Last reviewed: November 16, 2025

CDC recommends individual decision-making (also known as shared clinical decision-making) for COVID-19 vaccination of all people age 6 months and older. Among people age 6 months through 64 years, ACIP emphasizes that the risk-benefit of vaccination is most favorable for individuals who are at an increased risk for severe COVID-19 disease and lowest for individuals who are not at an increased risk. Details of the vaccination schedule are available here: www.cdc.gov/covid/hcp/vaccine-considerations/routine-guidance.html.

Of note, among previously unvaccinated people who are not moderately or severely immunocompromised, an initial vaccination series is recommended only for young children age 6 through 23 months. All others younger than age 65 years are recommended to receive a single dose of an age-appropriate 2025–2026 formula COVID-19 vaccine. People age 65 years and older are recommended to receive a second 2025–2026 formula COVID-19 vaccine dose 6 months later (minimum interval 2 months if using Comirnaty, Spikevax, or Nuvaxovid; minimum interval 3 months if using mNexspike).

Major U.S. professional medical societies have issued their own recommendations for the 2025–26 COVID-19 season that differ from CDC, primarily in their stronger, routine recommendations for vaccination of people at risk of severe COVID-19 illness:

Last reviewed: November 16, 2025

People who are moderately or severely immunocompromised are at increased risk for severe COVID-19 illness. ACIP and CDC recommend individual decision-making (also known as shared clinical decision-making) after a discussion with a healthcare professional (nurse, doctor, or pharmacist) for people age 6 months and older who are moderately or severely immunocompromised. They are recommended to receive at least 2 doses during the season. The CDC vaccination schedule for people with moderate or severe immunocompromise is available here: www.cdc.gov/covid/hcp/vaccine-considerations/immunocompromised.html.

The Infectious Diseases Society of America (IDSA) strongly recommends administration of age-appropriate 2025–2026 COVID-19 vaccinations to all adults and children with compromised immunity. They also recommend that household members and close contacts of immunocompromised people should be up to date with COVID-19 vaccination. See IDSA recommendations for full details: www.idsociety.org/Seasonal-RTI-Vaccinations-in-Immunocompromised-Patients/.  

Last reviewed: November 16, 2025

In past seasons, CDC recommended that all doses of COVID-19 vaccine given to children age 6 months through 4 years be from the same manufacturer. However, in the 2025–26 season, only Moderna’s Spikevax mRNA vaccine is licensed and recommended for use in children younger than age 5 years. All children in this age group who are vaccinated against COVID-19 should receive Spikevax, regardless of the brand they received in previous seasons. If the child is age 6 months through 23 months and received an incomplete (1- or 2-dose) initial COVID-19 vaccination series with Pfizer-BioNTech, a 3-dose initial series should be completed with Spikevax. It is not necessary to repeat the initial series.

In previously unvaccinated people age 5 years or older with moderate or severe immunocompromise, the same manufacturer is recommended for all initial COVID-19 vaccine series doses (either 2 doses of Nuvaxovid [if age 12 years or older] or 3 doses of an mRNA product). After completion of the initial series, any age-appropriate COVID-19 vaccine may be used in this age group.

CDC sets out conditions when it is acceptable to use an age-appropriate COVID-19 vaccine from a different manufacturer in any situation where the same manufacturer is recommended:

  • Same vaccine not available at the time of the clinic visit
  • Previous dose unknown
  • Person would otherwise not receive a recommended vaccine dose
  • Person starts but unable to complete a vaccination series with the same COVID-19 vaccine due to a contraindication
Last reviewed: November 16, 2025

Individuals with moderate to severe immunocompromise who have completed an initial COVID-19 series should receive two dose of 2025–2026 Formula COVID-19 vaccine this season with the second dose given 6 months later (minimum interval 2 months for Comirnaty, Spikevax, and Nuvaxovid; minimum interval 3 months for mNexspike).

In previous seasons, CDC recommended that additional doses of COVID-19 vaccine may be administered (with a minimum two-month interval) based on the clinical judgment of the individual’s healthcare provider and the recipient’s personal preference and circumstances. For the 2025–26 season, CDC has removed this general statement from its interim clinical considerations document (www.cdc.gov/covid/hcp/vaccine-considerations/immunocompromised.html). The CDC clinical considerations document now states, “On a case-by-case basis, providers caring for these patients may administer Moderna, Novavax, and Pfizer-BioNTech COVID-19 vaccines outside of the FDA and CDC dosing intervals when, based on their clinical judgment, the benefits of vaccination are deemed to outweigh the potential and unknown risks for the recipient who is immunocompromised.”

Last reviewed: November 16, 2025

Janssen (Johnson & Johnson) COVID-19 vaccine is no longer produced. The last remaining doses expired May 7, 2023. The history of Janssen vaccine use is relevant only to evaluation of an adult with moderate or severe immunocompromise because such individuals are recommended to receive an initial series of COVID-19 vaccine. History of a single dose of Janssen COVID-19 vaccine constitutes a complete initial series. A person with this history should follow the vaccination schedule recommended for an immunocompromised person who has already completed an initial vaccination series.

Last reviewed: November 16, 2025

Yes. Vaccination should be offered regardless of history of prior SARS-CoV-2 infection or long COVID.

Because COVID-19 illness temporarily boosts immunity, people who have recently had SARS-CoV-2 infection may consider delaying a 2025–2026 COVID-19 vaccine dose by up to 3 months following symptom onset or positive COVID-19 test (if asymptomatic). Studies have shown that a longer time between infection and vaccination may improve the immune response to vaccination. The likelihood of reinfection in the first few months following infection is low.

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. As with all vaccines, vaccination should be deferred until after recovery from moderate to severe illness.

Last reviewed: November 16, 2025

Adults age 65 years and older have the highest rates of hospitalization and death from COVID-19 illness. Protection against severe COVID-19 disease wanes after a few months. Disease surveillance data from the United States shows that SARS-CoV-2 viruses circulate and cause illness at varying levels year-round, with waves of activity observed historically in winter and late summer. It is not known whether this pattern will continue. This pattern is not like influenza, which usually causes a single epidemic wave (sometimes with more than one peak) each winter.

The 2025 CDC adult immunization schedule shows that adults age 65 years and older who are vaccinated against COVID-19 are recommended to receive a second dose of any 2025–2026 Formula COVID-19 vaccine 6 months after their first 2025–2026 Formula COVID-19 vaccine dose (minimum interval of 2 months for Comirnaty, Spikevax, and Nuvaxovid; minimum interval of 3 months for mNexspike). The second dose does not have to be the same brand as the first.

Last reviewed: November 16, 2025

CDC recommends waiting a minimum of 8 weeks (2 months) since the last 2024–2025 Formula COVID-19 vaccine to receive an age-appropriate 2025–2026 Formula COVID-19 vaccine, if using Comirnaty (Pfizer-BioNTech), Nuvaxovid (Sanofi-Novavax), or Spikevax (Moderna). They recommend a 3-month minimum interval when using mNexspike (Moderna); however, a dose of mNexspike administered at least 2 months after the most recent dose does not need to be repeated.

Any person who initiated a COVID-19 vaccination initial series (e.g., a child 6 months through 23 months of age or a person with moderate or severe immunocompromise) with a previous formulation should follow the age-appropriate recommended schedule for completion of their primary series with the current formulation of the same brand, if feasible. For the 2025–26 season, Spikevax is the only licensed and recommended option for children age 6 through 59 months, regardless of their vaccination history.

Last reviewed: November 16, 2025

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.

All available COVID-19 vaccines were initially administered under EUA. All available 2025–2026 Formula COVID-19 vaccines are fully licensed by FDA and no longer administered under EUA.

Last reviewed: November 16, 2025

Both the Pfizer-BioNTech COVID-19 Vaccine (Comirnaty) and the Moderna COVID-19 vaccines (Spikevax, mNexspike) are lipid nanoparticle-formulated, nucleoside-modified mRNA vaccines encoding the prefusion spike glycoprotein of SARS-CoV-2, the virus that causes COVID-19. The 2025–2026 formula mRNA vaccines target the Omicron JN.1 variant LP.8.1 strain. Moderna’s mNexspike was first licensed in 2025 for ages 12 years and older. It is designed to reduce the amount of mRNA required to elicit the same or slightly better immune response compared to Spikevax (10 mcg of mRNA versus 50 mcg of mRNA for an adult dose). Spikevax and mNexspike may be used interchangeably when both are age appropriate. Visit this CDC website for more details about how mRNA vaccines work: www.cdc.gov/covid/vaccines/how-they-work.html.

Last reviewed: November 16, 2025

Spikevax and mNexspike are both mRNA vaccines targeting the same strain of COVID-19. Spikevax is the original vaccine now licensed down to age 6 months. The mNexspike product is a newer mRNA vaccine licensed for ages 12 years and older with an advanced design that achieves the same or slightly better immune response with less mRNA in each dose (10 mcg in mNexspike compared to 50 mcg in adult doses of Spikevax). The two products may be used interchangeably when age appropriate.

In adults 65 years and older (and moderately or severely immunocompromised adults) who are recommended to receive a second dose 6 months after their first 2025–2026 formula dose, the minimum interval between the two recommended 2025–2026 season doses is 3 months for mNexspike, but only 2 months for the other COVID-19 vaccine products. If mNexspike is inadvertently administered after only 2 months, the dose counts as valid and does not need to be repeated.

Last reviewed: November 16, 2025

It is estimated that for every million doses administered, about one (~0.0001%) will result in an anaphylactic reaction following vaccination. The estimate for mRNA COVID-19 vaccines is slightly higher, at 2 to 5 anaphylactic reactions per million vaccinations given. With proper screening, most providers who administer thousands of vaccines in their lifetimes will never see an anaphylactic reaction.

Last reviewed: November 16, 2025

The original COVID-19 vaccines all targeted the spike protein of the original SARS-CoV-2 virus. The 2025–2026 formulation vaccines target the spike proteins of more recently circulating strains, known as the Omicron JN.1 lineage LP.8.1 strain (mRNA vaccines) or the JN.1 strain (Nuvaxovid adjuvanted protein subunit vaccine). The update is intended to boost production of antibodies that protect more effectively against disease caused by currently circulating Omicron subvariants.

The process of updating the strain without changing anything else is similar to the seasonal strain changes made for influenza vaccinations each year. Vaccine safety, side effects, and risk of allergic reactions are expected to be comparable to earlier formulations of vaccines of the same brand and dose. As with seasonal influenza vaccines, future COVID-19 vaccines can continue to be updated when needed, as the circulating viruses evolve.

Last reviewed: November 16, 2025

No. The last U.S. doses of Janssen COVID-19 Vaccine expired May 7, 2023.

Last reviewed: November 16, 2025

Nuvaxovid is the brand name of the adjuvanted protein subunit COVID-19 vaccine developed by Novavax and commercialized by Sanofi beginning in the 2025–26 season. It contains the Omicron JN.1 subvariant 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.

The 2025–2026 formulation of Nuvaxovid is FDA-licensed for use in people age 12 years or older. It is recommended as a single dose for people age 12 years through 64 years, given at least 8 weeks after the most recent dose of COVID-19 vaccine, regardless of the recipient’s vaccination history. People age 65 years or older and those age 12 years and older who are moderately or severely immunocompromised are recommended to receive 2 doses of 2025–2026 Formula COVID-19 vaccines, 6 months apart (with a minimum interval of 2 months between doses if using Nuvaxovid for both doses).

A 2-dose initial series is recommended for previously unvaccinated recipients who are moderately or severely immunocompromised, with the doses given at least 3 weeks apart. A third dose of any COVID-19 vaccine is recommended 6 months after the initial series is completed (with a minimum interval of 2 months between doses if using Nuvaxovid).

Last reviewed: November 16, 2025

The benefit of COVID-19 vaccination to an individual patient varies depending on the health status of the patient, their history of vaccination and COVID-19 infection, and the circulating COVID-19 strains. However, despite these variables, observational studies consistently show vaccination in all age groups provides measurable additional protection against hospitalization or death compared to those who are unvaccinated.

CDC published “Interim Estimates of 2024–2025 COVID-19 Vaccine Effectiveness Among Adults Aged ≥18 Years — VISION and IVY Networks, September 2024–January 2025” in MMWR on February 27, 2025 (www.cdc.gov/mmwr/volumes/74/wr/mm7406a1.htm). They concluded vaccine effectiveness (VE) of 2024–2025 COVID-19 vaccine was 33% against COVID-19–associated emergency department (ED) or urgent care (UC) visits among adults age18 years or older and 45%–46% against hospitalizations among immunocompetent adults age 65 years or older, compared with not receiving a 2024–2025 vaccine dose. VE against hospitalizations in immunocompromised adults age 65 years or older was 40%.

Last reviewed: November 16, 2025

CDC has a product-specific webpage for each COVID-19 vaccine (www.cdc.gov/vaccines/covid-19/info-by-product/index.html); however, at this writing the page has not been updated for the 2025–2026 Formula COVID-19 vaccines. You may access the package inserts for all four licensed 2025–26 COVID-19 vaccines on the Immunize.org COVID-19 main page: www.immunize.org/vaccines/a-z/covid-19/.

Last reviewed: November 16, 2025

CDC and ACIP recommend vaccination of all people age 6 months through 64 years based on individual decision-making (also known as shared clinical decision-making), with an emphasis that the risk-benefit of vaccination is most favorable for individuals who are at an increased risk for severe COVID-19 disease and lowest for individuals who are not at an increased risk, according to the CDC list of COVID-19 risk factors. Refer to CDC’s interim clinical considerations for COVID-19 vaccination for the specific dosing schedule: www.cdc.gov/covid/hcp/vaccine-considerations/routine-guidance.html#cdc_clinical_guidance_recomm_key-table-1-2025–2026-covid-19-vaccination-schedule-november-4-2025.

The American Academy of Pediatrics (AAP) has issued separate COVID-19 vaccination recommendations for children during the 2025–26 season. Refer to the full statement for details of their recommendations: https://doi.org/10.1542/peds.2025-073924. In summary, AAP recommends age-appropriate COVID-19 vaccination of the following groups of children:

  • All children age 6 months through 23 months
  • Residents of long-term care facilities or other congregate settings
  • Children who have never been vaccinated against COVID-19
  • Infants and children with household contacts who are at high risk for severe COVID-19
  • All children who are at risk of severe COVID-19 due to underlying conditions or treatments, including: chronic pulmonary disease, cardiovascular disease, gastrointestinal disorders, hepatic disease, hematologic disease, metabolic disorders, obesity, neurologic and neurodevelopmental conditions, immunosuppressive conditions, and rheumatologic or autoimmune disease
  • Children 2 through 18 years not in the above categories whose parent or guardian desires their protection from COVID-19
Last reviewed: November 16, 2025

This child should receive one dose recommended for his age at the time of the vaccination visit. At age 11 years, an age-appropriate single dose of either Comirnaty (Pfizer-BioNTech) or Spikevax (Moderna) mRNA vaccine is recommended. If the patient arrives in your clinic after turning 12 years old, the 2025–2026 Formula Nuvaxovid (Sanofi-Novavax) protein subunit vaccine and the mNexspike (Moderna) mRNA vaccine are also options.

Last reviewed: November 16, 2025

CDC states that a person who moves to an older age group before completing the initial series recommended for the younger age group should follow the schedule for the older age group and receive the vaccine product and dosage for the older age group. In this case, the child should receive one dose of 2025–2026 Formula Spikevax (Moderna) at least 8 weeks after the most recent dose of COVID-19 vaccine.

An initial series of COVID-19 vaccine is recommended for children 6 months through 23 months of age. Children 24 months through 59 months of age are recommended to receive only one dose of 2025–2026 Formula Spikevax regardless of their COVID-19 vaccination history.

Last reviewed: November 16, 2025

Moderately or severely immunocompromised children who transition from age 11 years to age 12 years during the initial vaccination series should complete the 3-dose series using the dosage for people ages 12 years and older for all doses received once they are age 12 years.

See www.cdc.gov/covid/hcp/vaccine-considerations/immunocompromised.html for additional details.

Last reviewed: November 16, 2025

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, and CDC continues to monitor for this adverse event following vaccination in infants and young children.

No cases of myocarditis were reported during the clinical trials for either vaccine. To date, post-authorization surveillance has not detected an increased risk for myocarditis and pericarditis following mRNA COVID-19 vaccination in children ages 6 months–4 years (Pfizer-BioNTech) and ages 6 months–5 years (Moderna).

Last reviewed: November 16, 2025


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Last reviewed: November 16, 2025

Comirnaty (Pfizer-BioNTech) mRNA COVID-19 vaccine is FDA-licensed for use in ages 5 years through 64 years with at least one underlying condition that puts them at risk for severe COVID-19 infection and individuals 65 years and older

mNexspike (Moderna) is FDA-licensed for use in ages 12 through 64 years with at least one underlying condition that puts them at risk for severe COVID-19 infection and individuals 65 years and older

Nuvaxovid (Sanofi-Novavax) is FDA-licensed for use in ages 12 through 64 years with at least one underlying condition that puts them at risk for severe COVID-19 infection and individuals 65 years and older

Spikevax (Moderna) mRNA COVID-19 vaccine is FDA-licensed for use in ages 6 months through 64 years with at least one underlying condition that puts them at risk for severe COVID-19 infection and individuals 65 years and older

Although the FDA licenses are limited in the age group younger than 65 years to those with underlying conditions that put them at risk for severe COVID-19 infection, the ACIP has recommended use based on individual decision-making (i.e., shared clinical decision-making) for all people age 6 months and older. This means that it is acceptable standard of care to offer COVID-19 vaccination to people in this age group without a high-risk condition when vaccination is desired.

Last reviewed: November 16, 2025

Clinical trial results for the original monovalent Pfizer-BioNTech COVID-19 Vaccine (administered as a two-dose primary series) demonstrated that 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.

The safety and side effects of the 2025–2026 formula are expected to be consistent with the previous formulations of the product.

Last reviewed: November 16, 2025

The 2025–2026 formula Nuvaxovid (Sanofi-Novavax) vaccine is an option for any person age 12 years or older who is due for a 2025–2026 updated vaccination. Below are listed the 2025–26 season dosing schedules (if using Nuvaxovid for all doses) for different ages and health conditions:

  • Age 12 through 64 years, not moderately or severely immunocompromised: one 2025–2026 formula dose, at least 8 weeks after most recent dose from a previous season
  • Age 65 years and older, not moderately or severely immunocompromised: two 2025–2026 formula doses 6 months apart (minimum interval 2 months)
  • Age 12 years or older, moderately or severely immunocompromised:
    • Previously unvaccinated: give 2 doses at least 3 weeks apart as an initial series, followed by a third dose about 6 months after dose 2 (minimum interval 2 months)
    • Previously completed an initial series of any COVID-19 vaccine (2 doses of Novavax protein subunit vaccine or 3 doses of an mRNA vaccine): give first 2025–2026 formula dose at least 8 weeks after most recent COVID-19 vaccine from the previous season, then give a second dose about 6 months later (minimum interval, 2 months)

See Immunize.org’s standing orders template for administration of 2025–2026 formula adjuvanted protein subunit vaccine to individuals age 12 years and older for details: www.immunize.org/wp-content/uploads/catg.d/p3141.pdf.

Last reviewed: November 16, 2025

Yes. Evidence continues to demonstrate that COVID-19 vaccination is safe and effective during any stage of pregnancy; the benefits of vaccination clearly outweigh any known or potential risks of COVID-19 vaccination during pregnancy. The currently 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 during pregnancy with non-replicating vaccines in general.

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 related to vaccination during pregnancy for mother or infant.

Pregnant women have historically been at an increased risk of severe disease, adverse pregnancy outcomes, and maternal death from COVID-19 infections. ACIP recommends the use of 2025–2026 COVID-19 vaccine during pregnancy based upon individual decision-making (i.e., shared clinical decision-making).

The American College of Obstetricians and Gynecologists (ACOG) recommends all pregnant women receive any age-appropriate 2025–2026 Formula COVID-19 vaccine if they have not already received one. Current ACOG recommendations are available here: www.acog.org/clinical/clinical-guidance/practice-advisory/articles/2020/12/covid-19-vaccination-considerations-for-obstetric-gynecologic-care.

Last reviewed: November 16, 2025

Pregnant women have historically been at an increased risk of severe disease, adverse pregnancy outcomes, and maternal death from COVID-19 infections. Studies have shown that antibodies produced after COVID-19 vaccination during pregnancy are transferred to the newborn, and COVID-19 vaccination during pregnancy reduces the risk of COVID-19 hospitalization in infants younger than 6 months.

ACIP recommends the use of 2025–2026 COVID-19 vaccine during pregnancy based upon individual decision-making (i.e., shared clinical decision-making) after a discussion with a nurse, doctor, or pharmacist.

The American College of Obstetricians and Gynecologists (ACOG) recommends all pregnant women receive any age-appropriate 2025–2026 Formula COVID-19 vaccine if they have not already received one. A person who is up to date on COVID-19 vaccination and becomes pregnant is not recommended to get an additional dose. Current ACOG recommendations are available here: www.acog.org/clinical/clinical-guidance/practice-advisory/articles/2020/12/covid-19-vaccination-considerations-for-obstetric-gynecologic-care.

Last reviewed: November 16, 2025


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Last reviewed: November 16, 2025

Yes. COVID-19 vaccination may be given during lactation.

Last reviewed: November 16, 2025

Please see CDC’s Interim Clinical Considerations for the Use of COVID-19 Vaccines for dosage guidance for detailed tables, including dosing intervals and options (www.cdc.gov/covid/hcp/vaccine-considerations/immunocompromised.html). You will also find the vaccination schedules for people who are moderately or severely immunocompromised in the Immunize.org standing orders templates for administration of COVID-19 vaccines:

In general, people who are moderately or severely immunocompromised and previously unvaccinated are recommended to receive a 2-dose (protein subunit) or 3-dose (mRNA) initial series of COVID-19 vaccine, with an additional dose 6 months later of any age-appropriate COVID-19 brand (minimum interval of 2 months for Nuvaxovid, Spikevax, or Comirnaty; 3-month minimum interval for mNexspike). CDC recommends use of the same manufacturer for all doses of the initial series when feasible. Spikevax and mNexspike are both made by Moderna and are interchangeable in ages 12 years and older.

Those who completed an initial series before the 2025–2026 formula vaccines were available should receive 2 doses of 2025–2026 Formula COVID-19 vaccine (any age-appropriate brand) about 6 months apart (minimum interval of 2 months for Nuvaxovid, Spikevax, or Comirnaty; 3-month minimum interval for mNexspike).

Immunocompromised people should be counseled that they may have a reduced immune response to COVID-19 vaccination. Continuing other infection prevention measures, such as wearing a face mask and avoiding crowds, can help limit their risk of exposure to the SARS-CoV-2 virus.

Pemivibart (Pemgarda, Invyvid) is a monoclonal antibody for COVID-19 pre-exposure prophylaxis in people who are moderately or severely immunocompromised and unlikely to mount an adequate immune response to COVID-19 vaccination and who meet the FDA-authorized conditions for use. See additional information from CDC at the immunocompromised link in the first paragraph.

Last reviewed: November 16, 2025

The conditions and treatments that CDC specifies may result in moderate or severe immunocompromise include but are not limited to:

  • Active treatment for solid tumor and hematologic malignancies
  • Hematologic malignancies associated with poor responses to COVID-19 vaccines regardless of current treatment status (e.g., chronic lymphocytic leukemia, non-Hodgkin lymphoma, multiple myeloma, acute leukemia)
  • Receipt of solid-organ transplant or an islet transplant and taking immunosuppressive therapy
  • Receipt of chimeric antigen receptor (CAR)-T-cell therapy or hematopoietic cell transplant (HCT) (within 2 years of transplantation or taking immunosuppressive therapy)
  • Moderate or severe primary immunodeficiency (e.g., common variable immunodeficiency disease, severe combined immunodeficiency, DiGeorge syndrome, Wiskott-Aldrich syndrome)
  • Advanced HIV infection (people with HIV and CD4 cell counts less than 200/mm³, history of an AIDS-defining illness without immune reconstitution, or clinical manifestations of symptomatic HIV) or untreated HIV infection
  • Active treatment with high-dose corticosteroids (i.e., 20 mg or more of prednisone or equivalent per day when administered for 2 or more weeks), 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 (e.g., B-cell-depleting agents)

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.

See CDC’s interim clinical considerations for this population: www.cdc.gov/covid/hcp/vaccine-considerations/immunocompromised.html.

Last reviewed: November 16, 2025

Yes. See revaccination considerations at www.cdc.gov/covid/hcp/vaccine-considerations/immunocompromised.html. This is the most current statement from CDC on COVID-19 revaccination:

Recipients of chimeric antigen receptor (CAR)-T-cell therapy or hematopoietic cell transplant (HCT) who received 1 or more doses of COVID-19 vaccine prior to or during treatment should be revaccinated. Revaccination should start at least 3 months (12 weeks) after transplant or CAR-T-cell therapy and should follow the currently recommended schedule for people who are unvaccinated.

Revaccination may also be considered for patients who received 1 or more doses of COVID-19 vaccine during treatment with B-cell-depleting therapies (e.g., rituximab, ocrelizumab) that were administered over a limited period (e.g., as part of a treatment regimen for certain malignancies) according to the currently recommended schedule for people who are unvaccinated. The suggested interval to start revaccination is about 6 months after completion of the B-cell-depleting therapy. Timing of vaccination for patients who receive B-cell-depleting therapies on a continuing basis (e.g., for treatment of certain autoimmune conditions such as rheumatoid arthritis or multiple sclerosis) is addressed in CDC’s considerations for timing of COVID-19 vaccination in relation to immunosuppressive therapies.

CDC continues to recommend that a patient’s clinical team is best positioned to determine the degree of immune compromise, need for revaccination, and appropriate timing of revaccination.

Last reviewed: November 16, 2025

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. Review the CDC’s considerations for COVID-19 vaccination of those on immunosuppressive therapies here: www.cdc.gov/covid/hcp/vaccine-considerations/immunocompromised.html#cdc_cg_special_populations_about-considerations-for-timing-of-covid-19-vaccination-in-relation-to-immunosuppressive-therapies.

On a case-by-case basis, providers caring for these patients may administer COVID-19 vaccines outside of the FDA and CDC dosing schedules based on their clinical judgment of what is most beneficial to the patient.

Last reviewed: November 16, 2025

CDC states that no additional medical documentation is required before administering COVID-19 vaccine. The patient’s self-attestation of a high-risk condition, including moderate or severe immunocompromise, is sufficient. Those who report moderate or severe immunocompromise should be offered the modified schedule for people with moderate or severe immunocompromise. Vaccinators should not deny COVID-19 vaccination to a person due to lack of documentation of a self-reported high-risk condition.

Last reviewed: November 16, 2025

Immunocompromised people who require an initial series of 3 doses of mRNA COVID-19 vaccine or two doses of Nuvaxovid (Sanofi-Novavax) adjuvanted protein COVID-19 vaccine should receive the initial series using COVID-19 vaccines from the same manufacturer, unless it is not feasible. If the same manufacturer cannot be used for all primary series doses (e.g., the brand is unavailable at the time of the vaccination visit, the previous brand is unknown, or the patient would not be vaccinated with the previous brand due to a contraindication or other reason), then administer another age-appropriate brand. Spikevax (Moderna) is the only licensed 2025–2026 Formula COVID-19 vaccine option for children younger than age 5 years. If the immunocompromised recipient is age 5 years or older, once the initial series is complete, any appropriate brand may be used for all subsequent doses. Spikevax and mNexspike are interchangeable: both vaccines are made by Moderna.

Last reviewed: November 16, 2025

The patient’s initial series is considered complete following a single dose of the Janssen COVID-19 Vaccine. People who are moderately or severely immunocompromised and have completed an initial series (no matter how long ago) should now receive 1 dose of an age-appropriate 2025–2026 Formula COVID-19 vaccine (at least 8 weeks after their most recent dose of a previous formulation). They should receive a second 2025–2026 Formula COVID-19 vaccine dose 6 months later (minimum interval 2 months for Comirnaty, Spikevax, and Nuvaxovid; minimum interval of 3 months if using mNexspike).

Last reviewed: November 16, 2025

The patient should receive a 2025–2026 COVID-19 mRNA dose now, of the same manufacturer as the initial two doses (if feasible), in order to complete the 3-dose initial mRNA vaccine series recommended for people with moderate or severe immunocompromise. Advise the patient that he should receive an additional 2025–2026 Formula COVID-19 dose of any brand in 6 months (minimum interval 2 months if using Comirnaty, Spikevax, or Nuvaxovid; minimum interval 3 months if using mNexspike).

Last reviewed: November 16, 2025

All COVID-19 vaccines are administered intramuscularly. Preparation details and dose volume vary by product. Most 2025-2026 formula products are now available in manufacturer-filled syringes.

Last reviewed: November 16, 2025

Yes. CDC 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/covid/hcp/vaccine-considerations/appendices.html.

Categories of errors covered in the CDC table include:

  • Site/route
  • Age
  • Product and dosage
  • Storage and handling
  • Incorrect intervals
  • Interchanging product types when not recommended

Ask the Experts refers our readers to this CDC table for the most current and comprehensive guidance on COVID-19 vaccine administration errors and how to manage them. For all vaccine administration errors the following steps are recommended: inform the patient of the error, report the error to VAERS (https://vaers.hhs.gov) unless CDC’s guidance states that the error does not need to be reported, evaluate why the error occurred, and implement strategies to prevent future errors.

Last reviewed: November 16, 2025

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). In the case of a subcutaneous injection, the patient should be advised of the possibility of self-limited local or systemic side effects.

Last reviewed: November 16, 2025

Providing a vaccine recipient with a COVID-19 vaccine VIS is recommended by CDC but not required. The requirement to provide the VIS to a patient is present only when a vaccine is included in the federal Vaccine Injury Compensation Program (VICP). COVID-19 vaccines are not included in the VICP at this time. The current official VIS and all available translations are available from Immunize.org: www.immunize.org/vaccines/vis/covid-19/.

Last reviewed: November 16, 2025

Periodically verify whether you are using the most current available 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. This resource is updated as needed with the dates of the most currently available materials from CDC and FDA.

Information from CDC is generally updated first on the CDC web page: Interim Clinical Considerations for Use of COVID-19 Vaccines in the United States: (www.cdc.gov/covid/hcp/vaccine-considerations/index.html).

Last reviewed: November 16, 2025

No. Simply administer the next dose that is currently recommended, using a vaccine from the same manufacturer, if feasible, even if previous doses in the series were an earlier formulation.

Last reviewed: November 16, 2025

CDC guidance allows for doses given up to 4 days before the recommended interval to be counted as valid – such doses do not need to be repeated. However, people should not be routinely scheduled to receive a dose earlier than recommended. Schedulers should offer appointments beginning on the date of the recommended interval or later.

Last reviewed: November 16, 2025

In this specific situation, a child age 6 months–23 months who received one 2024–2025 Formula Pfizer-BioNTech COVID-19 vaccine dose should receive 2 doses of Spikevax (Moderna) vaccine to complete the initial series.

Refer to the schedule tables on the CDC website (www.cdc.gov/covid/hcp/vaccine-considerations/routine-guidance.html#cdc_clinical_guidance_recomm_key-table-1-2025–2026-covid-19-vaccination-schedule-november-4-2025) or on the Immunize.org standing orders template for children age 6 months through 11 years (www.immunize.org/wp-content/uploads/catg.d/p3140a.pdf) for specific dosing intervals.

Last reviewed: November 16, 2025

Beginning with the 2025–2026 season, a single dose of 2025–2026 Formula Nuvaxovid adjuvanted protein COVID-19 vaccine is recommended for all recipients age 12 through 64 years who are not moderately or severely immunocompromised, regardless of their vaccination history. Those age 65 years or older are recommended to receive a second dose of any 2025–2026 Formula COVID-19 vaccine 6 months after the first 2025–2026 Formula dose (minimum interval 2 months if using Comirnaty, Spikevax, or Nuvaxovid; minimum interval 3 months if using mNexspike).

Last reviewed: November 16, 2025

An asymptomatic person who is scheduled for COVID-19 vaccination and is exposed to SARS-CoV-2 virus may be vaccinated. COVID-19 vaccination after exposure is not recommended as post-exposure prophylaxis, so vaccination should not be expected to prevent illness caused by past exposure. A person who is currently sick with a respiratory virus should defer vaccination until at least the recovery from the acute illness, and consider additional measures to prevent infecting others, in accordance with current CDC guidance. Healthcare facilities may have specific policies in place to reduce the risk of spread of respiratory viruses to healthcare staff and other patients.

People who recently had SARS-CoV-2 infection and are due for a COVID-19 vaccine may consider delaying the dose by up to 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. There is a low risk of reinfection in the weeks following an infection. A recipient’s individual risks for severe disease and current COVID-19 conditions in the community should be taken into consideration when deciding whether to delay vaccination up to 3 months after infection.

Last reviewed: November 16, 2025

Routine administration of all age-appropriate doses of vaccines at the same visit, also known as coadministration, is acceptable for children, adolescents, and adults if there are no contraindications at the time of the healthcare visit. COVID-19 vaccine may also be coadministered with nirsevimab or clesrovimab (RSV preventive antibody for infants), given in different syringes and at different anatomical sites. COVID-19 vaccines may also be given at any interval before or after any other vaccination.

There are special considerations for orthopoxvirus vaccination. There is no required minimum interval between receiving a dose of any COVID-19 vaccine and an orthopoxvirus vaccine, either Jynneos or ACAM2000 vaccine (e.g., for mpox prevention), regardless of which vaccine is administered first. However, use of Jynneos vaccine should be prioritized over ACAM2000 when co-administering a COVID-19 vaccine and an orthopoxvirus vaccine.

People, particularly adolescent or young adult males, who are recommended to be vaccinated against both mpox and COVID-19 might consider waiting 4 weeks between vaccines. This is because of the observed risk for myocarditis and pericarditis after receipt of ACAM2000 orthopoxvirus vaccine and COVID-19 vaccines, and the hypothetical risk for myocarditis and pericarditis after Jynneos vaccine. However, if a patient’s risk for mpox or severe disease due to COVID-19 is increased, administration of mpox and COVID-19 vaccines should not be delayed.

Last reviewed: November 16, 2025

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: November 16, 2025

The timing of CDC-recommended vaccination is unaffected by the receipt of COVID-19 monoclonal antibodies or convalescent plasma.

Last reviewed: November 16, 2025

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: November 16, 2025

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: November 16, 2025

Anaphylaxis occurs at a rate of approximately 5 cases per 1 million mRNA COVID-19 vaccinations administered. History of an anaphylactic reaction to a dose of mRNA COVID-19 vaccine is 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) 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_vaccine_special_topics_research-considerations-for-people-with-a-history-of-allergies-or-allergic-reactions.

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: November 16, 2025

This condition is not rare and is sometimes referred to as “COVID arm”. Future doses should be given as recommended. 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. It is not known whether individuals who experienced a delayed-onset injection site reaction after one dose will experience a similar reaction after future doses. These reactions are not believed to represent an increased risk for anaphylaxis after future doses.

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.

Last reviewed: November 16, 2025

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 potential 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.

Last reviewed: November 16, 2025

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