The F.D.A. has authorized additional shots for older Americans and those with certain immune deficiencies. Here’s what scientists know about who needs the doses, and when.
Aiming to protect Americans who are most vulnerable to the coronavirus, the Food and Drug Administration on Tuesday authorized a second booster dose of Covid vaccine for all adults 50 and older. The agency’s decision comes as the highly contagious Omicron subvariant BA.2 pummels Europe and threatens to do the same in the United States.
But the scientific evidence for fourth dose is incomplete, at best, and researchers do not agree on whether the shots are needed. Here are some factors to consider when making your…