Today, CDC Director Rochelle P. Walensky, M.D., M.P.H., endorsed the CDC Advisory Committee on Immunization Practices’ (ACIP) recommendation for a booster shot of the Pfizer-BioNTech COVID-19 vaccine in certain populations and also recommended a booster dose for those in high risk occupational and institutional settings. The Food and Drug Administration’s (FDA) authorization and CDC’s guidance for use are important steps forward as we work to stay ahead of the virus and keep Americans safe. This updated interim guidance from CDC allows for millions of Americans who are at highest risk for COVID-19 to receive a Pfizer-BioNTech COVID-19 booster shot to help increase their protection.