Ask the Experts: COVID-19: For Children under 12 Years

Results (6)

All children age 6 months and older should be vaccinated against COVID-19 with at least one dose of an updated (2023–2024) formulation vaccine. COVID-19 vaccination of children in this age group has been demonstrated to be safe and to prevent hospitalization and severe complications of COVID-19 illness. Both Pfizer-BioNTech and Moderna mRNA products are authorized for use in children down to 6 months of age. Novavax adjuvanted protein subunit vaccine is authorized for use beginning at age 12 years.

Most children younger than age 5 years initially require a primary series of two (Moderna) or three (Pfizer-BioNTech) doses of the same brand. The primary series may include doses of previously authorized formulations. CDC recommends use of the same brand (referred to as homologous doses) for all recommended doses given to children younger than age 5 years. If it is not possible to administer a homologous dose (the brand is unavailable at the time and location of the vaccination visit, the brand of a previous dose is unknown, the child would not be vaccinated with the homologous dose due to a contraindication or other reason), then administer the age-appropriate formulation of the available brand. A 3-dose primary series is required for all children and adults who have moderate or severe immunocompromise.

CDC has prepared infographics to make it easier to determine exactly what vaccination is due for each patient, based upon the patient’s age, vaccination history, and immunocompromised status. For most children younger than age 12 years, see this CDC infographic:

For children younger than 12 years who are moderately or severely immunocompromised, see this CDC infographic:

Last reviewed: March 19, 2024

This child should receive the dose recommended for his age at the time of the vaccination visit. At age 11 years, an age-appropriate single dose of either Pfizer-BioNTech or Moderna mRNA vaccine is recommended. If the patient arrives in your clinic after turning 12 years old, the 2023-2024 Formula Novavax protein subunit vaccine is also an option. If using the Novavax product, a previously unvaccinated person requires two doses, given 3 to 8 weeks apart, as a primary series.

Last reviewed: March 19, 2024

CDC states ( that a person who moves to an older age group between vaccine doses should receive the vaccine product and dosage for the older age group for all subsequent doses.

Children who initiated their primary series with Pfizer-BioNTech brand products and turn age 5 years during the primary series have two options:

  1. Receive a single dose of updated (2023–2024 Formula) Pfizer-BioNTech COVID-19 Vaccine, 0.3 mL/10 mcg (blue cap; blue label) on or after turning age 5 years. If the 10-mcg dose is the second dose, administer 3–8 weeks after the first dose; if it is the third dose, administer at least 8 weeks after the second dose, OR
  2. Complete the 3-dose series with updated (2023–2024 Formula) Pfizer-BioNTech COVID-19 Vaccine for ages 6 months–4 years, 0.3 mL/3 mcg (yellow cap; yellow label), as outlined in the FDA EUA.
Last reviewed: March 19, 2024

Children who initiate the Moderna 2-dose vaccination series at age 4 years and turn 5 years-old before receiving the second dose should receive the second dose in the series (no dose change is needed). See

Last reviewed: March 19, 2024

CDC states ( that if a person moves to an older age group between vaccine doses, they should receive the vaccine product and dosage for the older age group for all subsequent doses. Thus, CDC’s general recommendation in this case is to complete the primary series with the dose appropriate for a child age 12 years.

In the case of immunocompromised children who initiate the primary series before turning 12 years old and need to complete the primary series after turning 12, the FDA EUA also permits completing the entire 3-dose series with the formula authorized for children ages 5 through 11 years.

Last reviewed: March 19, 2024

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: March 19, 2024

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