The U.S. Food and Drug Administration (FDA) on Sept. 22 authorized booster doses for certain people already vaccinated against COVID-19 but at high risk of infection, including those over age 65 and those who are more likely to get exposed to the disease, such as health care, frontline, emergency and transportation workers, among others. The booster authorization only applies to Pfizer-BioNTech’s COVID-19 vaccine.

“After considering the totality of the available scientific evidence and the deliberations of our advisory committee of independent, external experts, the FDA amended the Emergency Use Authorization (EUA) for the Pfizer-BioNTech COVID-19 vaccine to allow for a booster dose in certain populations such as health care workers, teachers and day care staff, grocery workers and those in homeless shelters or prisons, among others,” said Dr. Janet Woodcock, acting FDA commissioner in a statement announcing the FDA’s decision. “As we learn more about the safety and effectiveness of COVID-19 vaccines, including the use of a booster dose, we will continue to evaluate the rapidly changing science and keep the public informed.”