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Young girl getting vaccine

FDA authorizes bivalent Pfizer COVID vaccine boosters for children under 5

March 14, 2023

Update: On March 16, the CDC updated its clinical guidance on boosters to match the expanded authorization from the FDA. For the latest news on COVID-19, visit

Children under 5 years who received the monovalent Pfizer-BioNTech COVID vaccine series soon may be eligible for a bivalent booster.

The Food and Drug Administration (FDA) has amended emergency use authorization for a bivalent booster in this age group at least two months after the primary series. The Centers for Disease Control and Prevention (CDC) will decide whether to recommend this use.

Peter Marks, M.D., Ph.D., director of the FDA’s Center for Biologics Evaluation and Research, said the move will give eligible families “an opportunity to update their children’s protection.”

“Currently available data show that vaccination remains the best defense against severe disease, hospitalization and death caused by COVID-19 across all age groups, and we encourage all eligible individuals to make sure that their vaccinations are up to date with a bivalent COVID-19 vaccine,” Dr. Marks said in a press release.

The bivalent booster includes the original SARS-CoV-2 strain plus an omicron BA.4/5 spike protein. Only children who received a primary series of three monovalent doses would be eligible. Those who received a bivalent dose as the third dose of their primary series are not eligible.

Vaccine uptake among young children has been low. Just 4% of children under 2 years and 6% of children ages 2-4 years have completed a primary series with any vaccine, according to CDC data.

The bivalent booster was tested in 60 children in this age group who had completed a monovalent Pfizer-BioNTech primary series. The clinical study found the booster elicited an immune response to both the original strain and BA.4/5.

The FDA assessed safety from several clinical studies. In a study that included 24 participants 6 months through 23 months who received a three-dose primary series of monovalent Pfizer-BioNTech vaccine and a bivalent booster dose, the most common side effects included irritability, drowsiness, injection site redness, pain and swelling, decreased appetite, fatigue and fever. Among 36 participants age 2-4 years, the most common side effects included fatigue, injection site pain, redness and swelling, diarrhea, vomiting, headache, joint pain and chills.




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