The FDA is expected to authorize 2nd boosters for people 50 and up

Anyone 50 years and older could soon be eligible for a second booster dose of the Moderna or Pfizer-BioNtech COVID-19 vaccine. The Food and Drug Administration is expected to authorize the additional booster shots without holding a meeting of its independent vaccine advisors.

The plan comes as evidence increases that protection from three shots is fading and a fourth shot would help boost immunity back up. And as BA.2, an even more contagious version of the omicron variant, continues to spread in the U.S., concern is mounting it could fuel another surge.

"We have a large number of people who are at least four to six months past their third shot," says Dr. Eric Topol, founder and director of the Scripps Research Translational Institute, who supports the move.

"Without protection against the omicron variant, particularly now we're confronting BA.2, there's a very high risk of hospitalization and death," he says.