On Mar. 29, 2022, Pfizer and BioNTech announced that the U.S. Food and Drug Administration (FDA) had expanded the emergency use of their COVID-19 vaccine to include a second booster dose in adults ages 50 years and older who have previously received a first booster of any authorized COVID-19 vaccine.

The FDA also has authorized a second booster dose for individuals 12 years of age and older who have been determined to have certain kinds of immunocompromise and who have received a first booster dose of any authorized COVID-19 vaccine. The additional booster is to be administered at least four months after the first booster and is the same formulation and strength as prior Pfizer-BioNTech COVID-19 vaccine doses.