FDA authorizes 2nd booster shots of Pfizer and Moderna COVID-19 vaccines for older adults and immunocompromised people

The FDA said the shots may be given to adults over 50 at least four months after they have received their first booster dose.

• The FDA has authorized second COVID-19 boosters for those older than 50 or with weakened immune systems.
• A second booster of Moderna or Pfizer's vaccine may be given at least four months after a first booster, it said.
• The extra shot will bolster immunity against severe COVID-19, and there were no safety concerns, the FDA said.

The US Food and Drug Administration has authorized a second COVID-19 vaccine booster shot from Pfizer and Moderna for older adults and immunocompromised individuals.

"This action will now make a second booster dose of these vaccines available to other populations at higher risk for severe disease, hospitalization and death," the FDA said in a statement on Tuesday.

It added: "Emerging evidence suggests that a second booster dose of an mRNA COVID-19 vaccine improves protection against severe COVID-19 and is not associated with new safety concerns."

Before, only certain immunocompromised individuals could get a single booster shot after three initial doses. 

Now, the FDA said a second booster shot of Moderna or Pfizer's coronavirus vaccine may be given to adults older than 50 at least four months after they have received a first booster dose of any authorized vaccine. 

It said the second booster shot from Pfizer can also be given to individuals older than 12 if they're immunocompromised — for example those who have undergone solid organ transplantation, or have other medical conditions of an "equivalent level of immunocompromise".

A second booster shot from Moderna can be given to individuals older than 18 if they are immunocompromised, as for Pfizer's shot, the FDA said.

In the case of both vaccines, they must be delivered at least four months after the initial booster shot, the FDA said. 

Recommendations haven't changed for those that received Johnson&Johnson's single dose vaccine, it said.

The FDA said in making its decisions about additional boosters, it examined data from a fairly small, ongoing clinical trial in Israel, as well as safety data from more than 700,000 people in Israel who received have received second boosters.

The FDA said it would continue to evaluate the data for the potential use of a second booster dose in other age groups. 

Leana Wen, a professor of public health at George Washington University said on Twitter Tuesday of the FDA decision: "On balance, this is the right call, as it allows individuals who choose additional protection now to get it."

The Centers for Disease Control and Prevention will now need to decide who should get the additional doses and when. The CDC didn't immediately respond to Insider's request for information on when this might be.

Any recommendations are expected to take into account risks and benefits, but this has become increasingly difficult as the pandemic has worn on. For example, the risk of severe disease varies amongst adults older than 50 depending on factors such as underlying health conditions, age, and time since last booster dose or previous infection.

"I've been getting multiple inquiries from lay friends over the past few days: 'What does this mean, and what should I do?' " John P. Moore, a professor of microbiology and immunology at Weill Cornell Medicine told the Washington Post. "I find it increasingly difficult to tell friends what they should do. It's becoming really problematic."