On May 25, 2022, Pfizer and BioNTech announced topline safety, immunogenicity and vaccine efficacy data from a Phase 2/3 trial evaluating a third 3-ﾵg 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.