More Covid Mysteries

Pedestrians in central London this week.Consider these Covid-19 mysteries:

In India — where the Delta variant was first identified and caused a huge outbreak — cases have plunged over the past two months. A similar drop may now be underway in Britain. There is no clear explanation for these declines.

In the U.S., cases started falling rapidly in early January. The decline began before vaccination was widespread and did not follow any evident changes in Americans’…MORE:NYTIMES