The death toll in the United States from the coronavirus pandemic passed 200,000 on Tuesday as the first day of fall brought questions about what may be ahead.

More deaths have been announced in the United States than in any other country, and reports of new coronavirus cases have climbed in the U.S. and parts of Europe in recent days, suggesting an uncertain new phase in the crisis.

When researchers in China were analyzing hospital data of patients with Covid-19, they noticed an odd trend: Very few of the sick patients regularly wore glasses.

In one hospital in Suizhou, China, 276 patients were admitted over a 47 day period, but only 16 patients — less than 6 percent — had myopia or nearsightedness that required them to wear glasses for more than eight hours a day. By comparison, more than 30 percent of similarly aged people in the region needed glasses for nearsightedness, earlier research had shown.