The Food and Drug Administration approved updated Covid-19 vaccines on Thursday, paving the way for the shots to soon land in pharmacies, doctors’ offices and health centers. The Centers for Disease Control and Prevention has said it will recommend that adults and children six months and older get updated vaccines. Here’s what to know.

How are the new shots different?

The F.D.A. approved one vaccine from Pfizer and one from Moderna. Representatives from the drug companies said that their shots were ready to ship immediately after approval.

Both vaccines target KP.2, a strain of the coronavirus that started to spread widely this spring. The variants that are most prevalent in the United States right now are very similar to KP.2, and so the vaccines should protect against them.

“When the match is very good, as we anticipate it would be with the current circulating strains, you get actual protection from infection for several months,” said Dr. Paul Sax, the clinical director of the division of infectious diseases at Brigham and Women’s Hospital in Boston.

The vaccine that rolled out last fall, by contrast, was geared at an older variant that has since petered out.