May 23, 2022 – Pfizer and BioNTech announced topline safety, immunogenicity and vaccine efficacy data from a Phase 2/3 trial evaluating a third 3-µg dose of the Pfizer-BioNTech COVID-19 Vaccine in children 6 months to under 5 years of age. Following a third dose in this age group, the vaccine was found to elicit a strong immune response, with a favorable safety profile similar to placebo.
Vaccine efficacy, a secondary endpoint in this trial, was 80.3% in children 6 months to under 5 years of age. This descriptive analysis was based on 10 symptomatic COVID-19 cases identified from seven days after the third dose and accrued as of April 29, 2022. The trial protocol specifies a formal analysis will be performed when at least 21 cases have accrued from seven days after the third dose. Final vaccine efficacy data will be shared once available.
In the Phase 2/3 trial, 1,678 children received a third dose of the 3-µg formulation at least two months after the second dose at a time when Omicron was the predominant variant. The immunogenicity analysis of geometric mean titer (GMT) ratio and seroresponse rate was conducted on a subset of study participants one month following the third dose in children 6 months to under 5 years of age, compared to the second dose in the 16- to 25-year-old population. Non-inferiority was met for both the 6- to 24-month-old population and the 2- to under 5-year-old population for both co-primary endpoints. Three 3-µg doses of the Pfizer-BioNTech COVID-19 Vaccine was well-tolerated in this age group, and no new safety signals were identified. The majority of adverse events were mild or moderate.
Studies in adults, adolescents, and children over 5 years of age continue to indicate that three doses of the Pfizer-BioNTech COVID-19 Vaccine enhances protection compared to two doses. The safety, immunogenicity and vaccine efficacy data for three doses of the vaccine in children under 5 years of age are consistent with the data seen in adults, suggesting that a third dose will provide similar benefit in children.