As Variants Have Spread, Progress Against the Virus in U.S. Has Stalled

United States coronavirus cases have increased again after hitting a low point late last month, and some of the states driving the upward trend have also been hit hardest by variants, according to an analysis of data from Helix, a lab testing company.

The country’s vaccine rollout has sped up since the first doses were administered in December, recently reaching a rolling average of more than three million doses per day. And new U.S. cases trended steeply downward in the first quarter of the year, falling by almost 80 percent...