On Sept. 23, 2021, Pfizer and BioNTech announced that the U.S. Food and Drug Administration (FDA) has authorized for emergency use a booster dose of the Pfizer-BioNTech COVID-19 Vaccine for individuals 65 years of age and older, individuals 18 through 64 years of age at high risk of severe COVID-19, and individuals 18 through 64 years of age whose frequent institutional or occupational exposure to SARS-CoV-2 puts them at high risk of serious complications of COVID-19 including severe COVID-19.

The booster dose was to be administered at least six months after completion of the primary series, and is the same formulation and dosage strength as the doses in the primary series.