FDA Authorizes Pfizer’s COVID-19 Bivalent Vaccine as Booster Dose for Infants, Preschoolers

The U.S. Food and Drug Administration recently amended the emergency use authorization (EUA) of the Pfizer–BioNTech COVID-19 bivalent vaccine to provide for a single booster dose of the vaccine in children who are six months through four years of age at least two months after completion of primary vaccination with three doses of the monovalent (single strain) Pfizer–BioNTech COVID-19 vaccine.

What Parents and Caregivers Need to Know

• Children six months through fours years of age who completed their three-dose primary series with the Pfizer–BioNTech COVID-19 monovalent vaccine more than two months ago are now eligible to receive a single booster dose of the Pfizer–BioNTech COVID-19 bivalent vaccine. 

• Since December 2022, children six months through four years of age who receive the first two doses of the monovalent Pfizer–BioNTech COVID-19 vaccine should complete their three-dose primary series with the Pfizer–BioNTech COVID-19 bivalent vaccine. These children are not eligible for a booster dose of a bivalent vaccine at this time and are expected to have protection against the most serious COVID-19 outcomes. Only those children will be eligible who completed their three-dose primary series with the monovalent Pfizer–BioNTech COVID-19 vaccine before this bivalent vaccine three-dose primary series authorization. 

• The Pfizer–BioNTech COVID-19 bivalent vaccine includes an mRNA component corresponding to the original virus strain to provide an immune response that is broadly protective against COVID-19 and an mRNA component corresponding to the Omicron variant BA.4 and BA.5 lineages to provide better protection against COVID-19 caused by this particular variant. 

“Today’s authorization provides parents and caregivers of children six months through four years of age who received the three-dose primary series with the monovalent Pfizer-BioNTech COVID-19 vaccine an opportunity to update their children’s protection by receiving a booster dose with the Pfizer-BioNTech COVID-19 vaccine, bivalent,” said Peter Marks, MD, PhD, director of the FDA’s Center for Biologics Evaluation and Research. “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.” 

FDA Evaluation of Available Effectiveness Data

For the authorization of a single booster dose of the Pfizer–BioNTech COVID-19 bivalent vaccine for the abovementioned subset of children, the FDA evaluated immune response data from 60 children in this age group who had completed primary vaccination with three doses of Pfizer–BioNTech COVID-19 monovalent vaccine and received a booster dose of Pfizer–BioNTech COVID-19 bivalent vaccine in a clinical study. Around one month later, the study participants demonstrated an immune response to both the original SARS-CoV-2 virus strain and Omicron BA.4/BA.5 subvariants.

In addition, the authorization is supported by the FDA’s previous analyses of the effectiveness of primary vaccination with the monovalent Pfizer–BioNTech COVID-19 vaccine in individuals 16 years of age and older and individuals six months through four years of age, and previous analyses of immune response data in adults greater than 55 years of age who had received one booster dose with an investigational Pfizer–BioNTech bivalent COVID-19 vaccine (for original and Omicron BA.1 subvariants).

FDA Evaluation of Available Safety Data

The safety of the Pfizer–BioNTech COVID-19 bivalent vaccine as a booster dose in infants and preschoolers of the said vaccination profile is based on the following safety data previously evaluated by the FDA: 

• A clinical study that evaluated a booster dose with Pfizer–BioNTech’s investigational bivalent COVID-19 vaccine (original and Omicron BA.1 subvariant), in individuals greater than 55 years of age

• Clinical studies which evaluated primary vaccination with the monovalent Pfizer–BioNTech COVID-19 vaccine in individuals six months of age and older

• Clinical studies which evaluated booster vaccination with monovalent Pfizer–BioNTech COVID-19 vaccine (previously, but no longer, authorized) in individuals five years of age and older, and

• Postmarketing safety data with the monovalent and bivalent Pfizer–BioNTech COVID-19 vaccines

In addition, among individuals six months of age and older, safety was assessed in participants in two clinical studies. In one study, participants six months through 11 years of age who were previously vaccinated with a three-dose primary series of Pfizer–BioNTech COVID-19 monovalent vaccine received a booster dose of the Pfizer–BioNTech COVID-19 bivalent vaccine. 

Among 24 participants, from six months through 23 months, the most common side effects included irritability, drowsiness, injection site redness, pain and swelling, decreased appetite, fatigue, and fever. Among 36 participants from two to four years of age, the most common side effects included fatigue, injection site pain, redness and swelling, diarrhea, vomiting, headache, joint pain, and chills. Among 113 participants of five through 11 years of age, the most common side effects included, fatigue, headache, muscle pain, joint pain, chills, fever, vomiting, diarrhea, injection site pain, swelling and redness, and swelling of the lymph nodes in the same arm of the injection. 

In another study, 316 participants 12 years of age and older who were previously vaccinated with a two-dose primary series and a single booster dose of Pfizer–BioNTech COVID-19 monovalent vaccine, received a second booster dose with the Pfizer–BioNTech COVID-19 bivalent vaccine. The most commonly reported side effects by the participants in this age group were the same as those reported by those in the five to 11 years age group.

The safety data accrued with the investigational bivalent vaccine (original and Omicron BA.1 subvariant) and with the Pfizer–BioNTech COVID-19 monovalent vaccine are relevant to the Pfizer–BioNTech COVID-19 bivalent vaccine, because these vaccines are manufactured using the same process.

The fact sheets for recipients, caregivers, and health care providers include information about the vaccine’s potential side effects, as well as the risks of myocarditis and pericarditis.

The amendment to the EUA was issued to Pfizer Inc.

- This press release was originally published on the U.S. Food and Drug Administration website