We may have been kidding ourselves about the likelihood of children spreading the coronavirus. A major study conducted in South Korea shows that children under 10 do give the virus to each other and to adults less often than other age groups do, the New York Times reports. But it does happen. And particularly worrisome as schools prepare to reopen is the finding that those ages 10 to 19 spread the coronavirus even more often than adults do. This study contradicts some research, but a Harvard expert called the earlier work flawed. The South Korean study, which included contact tracing, "is very carefully done, it’s systematic and looks at a very large population," he said. "It's one of the best studies we’ve had to date on this issue."
One theory for why the youngest spread the virus about half as often as adults is that children exhale closer to the ground, away from adults. And they exhale less air. There are few answers about why older children are so infectious. It might be because they often combine the physical size of adults with the lack of hygiene of young children. "We can speculate all day about this," one expert said, per the Times, "but we just don’t know." Even without definitive answers, an epidemiologist said, children would have to be found to not transmit the virus at all for it to be completely safe for them to gather. "Putting them together in schools, having them mix with teachers and other students will provide additional opportunities for the virus to move from person to person,” he said. An infectious disease expert warned: "There will be transmission. What we have to do is accept that now and include that in our plans." (Read more coronavirus stories.)