Pfizer Inc. and BioNTech SE announced the U.S. Food and Drug Administration (FDA) expanded emergency use authorization (EUA) to include a booster dose after completion of the primary series of the Pfizer-BioNTech COVID-19 Vaccine in children 5 through 11 years of age. The booster dose is given at least five months after the second dose of the two-dose primary series and is the same 10-µg dose of the Pfizer-BioNTech COVID-19 Vaccine. To date, more than 8 million5- to 11-year-olds in the U.S. have completed primary series. The expanded EUA is based on data from the Phase 2/3 clinical trial, which showed that a booster dose of the Pfizer-BioNTech COVID-19 Vaccine elicited a strong immune response in this age group, generating neutralizing antibodies against both the Omicron variant and wild-type SARS-CoV-2 virus regardless of prior SARS-CoV-2 infection. No new safety signals were observed. The third dose was well tolerated, with a safety profile similar to the two-dose primary series. This Phase 2/3 data builds on efficacy data for the primary two-dose series which showed 90.7% efficacy in children 5 through 11 without prior SARS-CoV-2 infection, measured from 7 days after the second dose, at a period when Delta was the prevalent strain. The companies have already submitted an application to the European Medicines Agency for a booster dose in this age group and are planning to file with other regulatory agencies around the world. The Pfizer-BioNTech COVID-19 Vaccine is the only COVID-19 vaccine authorized for use in the U.S. for children 5 through 11 years of age. The Phase 1/2/3 clinical trial evaluating the safety, tolerability, and immunogenicity of a3-µg formulation of the Pfizer-BioNTech COVID-19 Vaccine on a three-dose schedule in children ages 6 months through 4 years (also known as under 5) is ongoing. Initial data is expected in the coming weeks.