WASHINGTON - The US Food and Drug Administration (FDA) on Wednesday authorized booster shots of Pfizer's COVID-19 vaccine for people aged 65 and older or at high-risk.

"After considering the totality of the available scientific evidence and the deliberations of our advisory committee of independent, external experts, the FDA amended the EUA (emergency use authorization) 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 Acting FDA Commissioner Janet Woodcock.

"This pandemic is dynamic and evolving, with new data about vaccine safety and effectiveness becoming available every day. 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," said Woodcock.

The FDA said boosters are authorized for people between the ages of 18 through 64 who are at high risk, as well as those "whose frequent institutional or occupational exposure" to the virus puts them at high risk of serious complications of COVID-19.

The agency said booster doses are to be administered at least six months after completion of the second shot.