FAQs for the Interim Clinical Considerations for COVID-19 Vaccination
This page has answers to commonly asked questions about the Interim Clinical Considerations for COVID-19 Vaccination.
For information about COVID-19 vaccine storage, preparation, and administration, see U.S. COVID-19 Vaccine Product Information.
The updated (2023–2024 Formula) Moderna and Pfizer-BioNTech (mRNA) and updated (2023–2034 Formula) Novavax (protein subunit) COVID-19 vaccines are currently available and recommended for use in the United States.
For more information, see COVID-19 vaccines.
The mRNA vaccines are recommended for people ages 6 months and older and the Novavax vaccine for people ages 12 years and older. The number of updated (2023–2024 Formula) vaccine doses a person needs depends on age, COVID-19 vaccination history, vaccine manufacturer, and immune status.
For information on the current COVID-19 vaccination schedule, see the vaccination schedule for people who are not immunocompromised and people who are moderately or severely immunocompromised.
There is no preferential recommendation for the use of one COVID-19 vaccine over another when more than one age-appropriate vaccine is recommended. There are currently three updated (2023–2024 Formula) COVID-19 vaccines recommended for use in the United States: the mRNA vaccines, Moderna and Pfizer-BioNTech, recommended for ages 6 months and older, and Novavax, recommended for ages 12 years and older.
For more information, see COVID-19 vaccines.
In accordance with General Best Practice Guidelines for Immunization, routine administration of all age-appropriate doses of vaccines simultaneously, also known as coadministration, is recommended for children, adolescents, and adults for whom no specific contraindications exist at the time of the healthcare visit.
Providers may simultaneously administer COVID-19, influenza, and respiratory syncytial virus (RSV) vaccines to eligible patients; the Health Alert Network (HAN) published on September 5, 2023, may be consulted for additional information about simultaneous administration of these vaccines.
For additional considerations if administering a COVID-19 vaccine and an orthopoxvirus (mpox) vaccine, see Interim Clinical Considerations for Use of JYNNEOS and ACAM2000 Vaccines during the 2022 U.S. Mpox Outbreak.
For more information, see Simultaneous administration of COVID-19 vaccines with other vaccines.
COVID-19 vaccine doses from the same manufacturer should be administered whenever recommended. In the following circumstances, an age-appropriate COVID-19 vaccine from a different manufacturer may be administered:
- Same vaccine not available at the vaccination site 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.
The COVID-19 vaccination schedules for People who are not moderately or severely immunocompromised and People who are moderately or severely immunocompromised should be consulted for age-specific information; see also Appendix B for recommended actions following interchangeability-related errors or deviations in administration of COVID-19 vaccines.
For additional information, see Interchangeability of COVID-19 vaccines.
Children ages 6 months–4 years who received the first 2 doses of an mRNA COVID-19 vaccine from different manufacturers should follow a 3-dose schedule. A third dose of either updated (2023–2024 Formula) mRNA vaccine (Moderna or Pfizer-BioNTech) should be administered at least 8 weeks after the second dose.
For additional information, see Interchangeability of COVID-19 vaccines.
Children who are NOT moderately or severely immunocompromised
Children in this group who transition from age 4 years to age 5 years during the initial 3-dose Pfizer-BioNTech COVID-19 vaccination series should receive 1 dose of updated (2023–2024 Formula) Pfizer-BioNTech COVID-19 Vaccine, 0.3 mL/10 ug (blue cap; blue label) on or after turning age 5 years. Alternatively, these children may complete the 3-dose series with the updated (2023–2024 Formula) Pfizer-BioNTech COVID-19 Vaccine for ages 6 months–4 years, 0.3 mL/3 ug (yellow cap; yellow label).
Children who ARE moderately or severely immunocompromised
Children in this group who transition from age 4 years to age 5 years during the initial 3-dose Pfizer-BioNTech vaccination series should complete the 3-dose series with updated (2023–2024 Formula) Pfizer-BioNTech COVID-19 Vaccine, 0.3 mL/10 ug (blue cap; blue label) for all doses received on or after turning age 5 years. Alternatively, these children may complete the 3-dose series with the updated (2023–2024 Formula) Pfizer-BioNTech COVID-19 Vaccine for ages 6 months–4 years, 0.3 mL/3 ug (yellow cap; yellow label).
For additional information, see:
Children who are NOT moderately or severely immunocompromised
Children in this group who transition from age 4 years to age 5 years during the initial 2-dose Moderna COVID-19 vaccination series should complete the series with updated (2023–2024 Formula) Moderna COVID-19 Vaccine, 0.25 mL/25 ug (dark blue cap; green label); there is no dosage change.
Children who ARE moderately or severely immunocompromised
Children in this group who transition from age 4 years to age 5 years during the initial 3-dose Moderna vaccination series should complete the 3-dose series with updated (2023–2024 Formula) Moderna COVID-19 Vaccine, 0.25 mL/25 ug (dark blue cap; green label); there is no dosage change.
For additional information, see:
Moderna: Should receive updated (2023–2024 Formula) Moderna COVID-19 Vaccine, 0.5 mL/50 ug (dark blue cap; blue label) for all doses received on or after turning age 12 years. Alternatively, they may complete the 3-dose series with updated (2023–2024 Formula) Moderna COVID-19 Vaccine for children ages 5–11 years, 0.25 mL/25 ug (dark blue cap; green label).
Pfizer-BioNTech: Should receive updated (2023–2024 Formula) Pfizer-BioNTech COVID-19 Vaccine, 0.3 mL/30 ug (gray cap; gray label) for all doses received on or after turning age 12 years. Alternatively, they may complete the 3-dose series with updated (2023–2024 Formula) Pfizer-BioNTech COVID-19 Vaccine for children ages 5–11 years, 0.3 mL/10 ug (blue cap; blue label),
For additional information, see:
Yes, for children ages 6 months–4 years who require more than one dose of updated (2023–2024 Formula) mRNA vaccine, all doses of vaccine must come from the same manufacturer (i.e., homologous dosing). This includes children who are unvaccinated and initiating the vaccination series, and those who were previously vaccinated and completing the series.
For information on circumstances in which doses from different manufacturers (i.e., heterologous dosing) may be considered, see Interchangeability of COVID-19 vaccines.
For information on the current COVID-19 vaccination schedule, including age-specific dosages and dosing intervals, see the vaccination schedule for people who are not immunocompromised.
People ages 65 years and older should only receive the recommended number of doses of updated (2023–2024 Formula) mRNA or Novavax vaccine; an additional dose of COVID-19 vaccine is not recommended at this time.
The Advisory Committee on Immunization Practices (ACIP) will continue to evaluate available data on the epidemiology of COVID-19 and the safety and effectiveness of COVID-19 vaccines. Based on these assessments, ACIP will update COVID-19 vaccine policy and guidance as needed, especially for people at increased risk for severe COVID-19, including people ages 65 years and older.
For additional information, see the vaccination schedule for people who are not immunocompromised.
Yes, people who are moderately or severely immunocompromised have the option to receive 1 additional dose of an age-appropriate updated (2023–2024 Formula) vaccine at least 2 months following the last recommended updated (2023–2024 Formula) COVID-19 vaccine dose. Further additional doses of updated (2023–2024 Formula) vaccine may be administered, informed by the clinical judgement of a healthcare provider and personal preference and circumstances. Any further additional doses should be administered at least 2 months after the last COVID-19 vaccine dose.
For additional information, see the COVID-19 vaccination schedule for people who are moderately or severely immunocompromised.
For people who are moderately or severely immunocompromised, the vaccine (Moderna, Novavax, or Pfizer-BioNTech) for the additional doses depends on their age and the vaccine they received for their initial series.
- Ages 6 months–4 years
- Previously received Moderna: Only Moderna
- Previously received Pfizer-BioNTech: Only Pfizer-BioNTech
- Ages 5–11 years
- Either Moderna or Pfizer-BioNTech regardless of which vaccine was received for their initial series doses
- Ages 12 years and older
- Moderna, Novavax, or Pfizer-BioNTech regardless of which vaccine was received for their initial series doses
For additional information, see the COVID-19 vaccination schedule for people who are moderately or severely immunocompromised.
People can self-attest to their moderately or severely immunocompromised status and should be vaccinated according to the schedule for people who are moderately or severely immunocompromised. Health care professionals, vaccinators, and clinic administrators should not deny COVID-19 vaccination to a person because of a lack of documentation.
Recipients of HCT or CAR-T cell therapy 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 after treatment and follow the currently recommended schedule for people who are unvaccinated.
For additional information, see:
- Considerations for COVID-19 revaccination
- COVID-19 vaccination schedule for people who are moderately or severely immunocompromised
Antibody testing is not currently recommended to assess the need for vaccination in an unvaccinated person or to assess immunity to SARS-CoV-2 following COVID-19 vaccination or after SARS-CoV-2 infection. Antibody tests for SARS-CoV-2 look for the presence of antibodies made in response to a previous infection or vaccination. Antibodies are an indicator of the body’s efforts to fight off the SARS-CoV-2 virus. None of the currently authorized SARS-CoV-2 antibody tests have been validated to assess specific immunity or protection from SARS-CoV-2 infection or vaccination.
For additional information, see:
CDC recommends COVID-19 vaccination for all people ages 6 months and older, including people with a history of SARS-CoV-2 infection.
Prior infection: Offer vaccination regardless of history of prior symptomatic or asymptomatic SARS-CoV-2 infection, including to people with prolonged post-COVID-19 symptoms and people who experienced SARS-CoV-2 infection (symptomatic or asymptomatic) after vaccination. People who recently had SARS-CoV-2 infection may consider delaying their COVID-19 vaccine dose by 3 months from symptom onset or positive test (if infection was asymptomatic).
Current infection: Defer vaccination of people with known current SARS-CoV-2 infection until the person has recovered from acute illness (if the person has symptoms) and until criteria have been met for them to discontinue isolation.
Laboratory testing is not recommended for the purpose of vaccine decision-making.
For more information, see COVID-19 vaccination and SARS-CoV-2 infection.
Yes. CDC recommends COVID-19 vaccination for people who are pregnant, trying to get pregnant now, or who might become pregnant in the future; and people who are breastfeeding. Maternal vaccination has also been shown to protect infants younger than age 6 months from severe COVID-19 and hospitalization. COVID-19 vaccines are recommended for all vaccine-eligible populations including people who are pregnant or lactating.
For more information, see COVID-19 Vaccines While Pregnant or Breastfeeding.
In accordance with General Best Practice Guidelines for Immunization, preterm infants (infants born before 37 weeks’ gestation), regardless of birth weight, should receive COVID-19 vaccination, once eligible at age 6 months or older, at their chronological age and according to the same schedule and guidance as for full-term infants and children.
Infants of mothers who were vaccinated and/or had COVID-19 or SARS-CoV-2 infection before or during pregnancy should be vaccinated according to the recommended schedule.
For more information, see COVID-19 Vaccines While Pregnant or Breastfeeding.