Here’s what to know about the FDA authorizing an additional COVID-19 booster shot for some people

A healthcare worker prepared the Moderna COVID-19 vaccine booster.Toru Hanai/Bloomberg

The US Food and Drug Administration on Tuesday authorized a second booster dose for people 50 and older and some immunocompromised people in an effort to boost protection against COVID-19 for those who are at higher risk for more severe outcomes.

Hours later, the US Centers for Disease Control and Prevention recommended the extra shots.

Here’s what you need to know:

What did the FDA do?

The FDA authorized a second booster dose of the Moderna or Pfizer vaccines for people 50 and older at least four months after they received their first booster shot of any COVID vaccine.

The agency also said severely immunocompromised people 12 and older are now eligible for an additional Pfizer booster dose four months after their first booster shot, or, if they’re 18 or older, a booster of the Moderna vaccine.

Health officials have recommended that some people who are immunocompromised receive three doses of a COVID-19 shot as their primary vaccination course, and US regulators had already authorized a booster dose for the group. The FDA’s decision Tuesday means people who are immunocompromised will be eligible for a total of five COVID shots.

The FDA noted that booster guidance for other groups is not changing.

“The agency will continue to evaluate data and information as it becomes available when considering the potential use of a second booster dose in other age groups,” the statement said.

In previous decisions about expanding access to vaccinations, an independent panel of experts has weighed in. In this decision, the FDA went ahead without input from the group.

Why did they expand booster authorization?

Evidence suggests that the second booster will provide protection from more severe outcomes as a result of COVID-19 in older and immunocompromised people, Dr. Peter Marks, director of the FDA’s Center for Biologics Evaluation and Research said in a statement about the decision.

In a statement announcing its recommendation, the CDC said booster shots provide “substantial benefit,” adding that during the Omicron surge, people who had received booster shots were 21 times less likely to die from COVID-19 compared to unvaccinated people, and seven times less likely to be hospitalized.

CDC Director Dr. Rochelle Walensky said in the statement that people 50 and older and those with compromised immune systems “are the most likely to benefit from receiving an additional booster dose at this time,” and that the agency will “continue to evaluate the need for additional booster doses for all Americans.”

Health officials looked at data from Israel, which allowed a fourth vaccine dose for people 60 and older at least four months after their last shot. Preliminary data made public last week suggested increased protection in that age group.

What are experts saying about the decision?

Dr. Sanjay Gupta said on CNN that the spread of the Omicron subvariant, BA.2, which is fueling a rise in cases in some European countries and has become the dominant variant in the United States, is “driving” the FDA’s decision.

“It’s not clear that [BA.2] is more lethal, that it’s causing more disease necessarily, but in people who don’t have adequate immunity and are otherwise at risk, either because of age or because of being immune-compromised, that’s the biggest sort of concern, is that now this is so contagious out there that if you’ve kind of gotten away with things so far, despite not having adequate immunity, this is likely to catch up with you.”

“More contagious, less lethal, except for those people who are most at risk that are still vulnerable,” Gupta said.

The FDA has authorized a second booster shot for Americans aged 50 and older. @drsanjaygupta discusses how the dominance of Omicron subvariant BA.2 in the US may have driven the decision. pic.twitter.com/BhPZsCS6AR

— CNN (@CNN) March 29, 2022

Material from Globe wire services was used in this report.