As the virus continues to mutate, the C.D.C. urged Americans to roll up their sleeves again for annual vaccinations.
ยฉ Jenn Ackerman for The New York Times
Across every age group, a vast majority of Americans who were hospitalized for Covid did not receive one of the shots offered last fall, according to data presented at a meeting of the C.D.C.
The panel endorsed targeting a variant of the coronavirus that is now receding, though some officials suggested aiming at newer versions of the virus that have emerged in recent weeks.
ยฉ Jamie Kelter Davis for The New York Times
Studies have shown that protection against serious illness from Covid-19 tends to improve as the vaccines more precisely target dominant strains, according to the Food and Drug Administration.