The U.S. Food and Drug Administration (FDA) announced Friday that it has authorized boosters of the Pfizer/BioNTech and Moderna COVID-19 vaccines for all adults, CNN reports. 

Today, we amended the EUAs for the Moderna & Pfizer-BioNTech COVID-19 vaccines authorizing use of a single booster dose to be administered to those 18+ years old after completion of a primary vax series with any FDA-authorized/approved #COVID19 vaccine. https://t.co/BpITYtl90d pic.twitter.com/r49GJj5Opo

— U.S. FDA (@US_FDA) November 19, 2021

Before Friday, boosters were authorized for anyone 65 and older who had been vaccinated with the Pfizer or Moderna vaccines at least 6 months ago and for adults who were considered at high risk of infection or severe disease. 

Now, the FDA has expanded emergency use authorization for booster doses of both the mRNA vaccines beyond those two groups.

Acting FDA Commissioner Dr. Janet Woodcock issued a statement on the FDA's decision, which said, in part: "Authorizing the use of a single booster dose of either the Moderna or Pfizer-BioNTech COVID-19 vaccine for individuals 18 years of age and older helps to provide continued protection against COVID-19, including the serious consequences that can occur, such as hospitalization and death." 

Pfizer and BioNTech asked for authorization last week, basing their request on the results of a Phase 3 trial involving more than 10,000 participants.

The trial revealed that boosters were safe and had an efficacy of 95 percent against symptomatic COVID-19 compared with the two-dose vaccine schedule. This was during a time when Delta was the dominant strain.

In October, Pfizer released the booster efficacy data, and this information has yet to be peer-reviewed or published.

Moderna requested authorization of its 50-microgram booster dose for all adults Wednesday,  and the company said the FDA based the EUA on the "totality of scientific evidence shared by the company," including data that showed neutralizing antibodies had waned at about six months.

Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, referred to recent data from Israel during an interview with CNN, saying that studies there showed people age 60 and older who received a booster were less likely to become severely ill than vaccinated people who had not received a booster.

In contrast, rates of severe disease remained highest among those who weren't vaccinated.