The U.N. chief warned that the world faces a “generational catastrophe” because of school closures, with more than a billion students at home. In a video message, he urged countries to suppress the virus sufficiently to allow schools to reopen, calling the coronavirus pandemic “the largest disruption of education ever.”

A policy brief published alongside Guterres’s message emphasized that suppressing transmission of the virus is “the single most significant step” leaders can take toward reopening schools…

Many large school districts have already announced a delay in on-campus learning, including those in New York and Los Angeles and in the D.C. area.

But schools are opening elsewhere, making the country a patchwork of open and closed as many students begin classes in one form or another this month. The United States leads the world in confirmed coronavirus cases, with more than 4.7 million, and has recorded more than 153,000 deaths. Tuesday marked the ninth consecutive day in which the country averaged more than 1,000 coronavirus-related fatalities following the recent peak in new cases.