The Pandemic Is Receding in the Worst Hotspots. Will It Last?

LONDON — A month ago, the pandemic looked bleak. More than 750,000 coronavirus cases were tallied worldwide in a single day. Infections surged across the entire United States. New variants identified in the United Kingdom, Brazil and South Africa threatened the rest of the world.

But the last month has brought a surprisingly fast, if partial, turnaround. New cases have declined to half their peak globally, driven largely by steady improvements in some of the same places that weathered devastating outbreaks this winter.

Cases are an imperfect measure, and uneven...