A more rational concern—also cited by these governors—addresses the possibility that asymptomatic schoolchildren could end up passing the virus to their teachers, parents, or other adults. But even here the balance of existing evidence suggests this worry is largely unfounded. “Children under 10 are less likely to get infected than adults, and if they get infected, they are less likely to get seriously ill,” said Kári Stefánsson, in an interview following the publication of an Icelandic study he coauthored in The New England Journal of Medicine. “What is interesting,” he continued, “is that even if children do get infected, they are less likely to transmit the disease to others than adults. We have not found a single instance of a child infecting parents.”

The same conclusion has been reached by many others. A report released by the National Institute for Public Health and the Environment for the Netherlands found “no indications that children younger than 12 years were the first to be infected within the family.” Rather, it remarked, “The virus is mainly spread between adults and from adult family members to children.” A report of the WHO-China Joint Mission on Coronavirus Disease stated: “Of note, people interviewed by the Joint Mission Team could not recall episodes in which transmission occurred from a child to an adult.”

A joint press release in late April from three associations of French pediatricians stated that the “risk of infection for adults is mainly due to contact between adults themselves (teachers, staff, and parents grouped out of school).” It encouraged the return to school even for children with chronic diseases, as “delaying this return appears to be of no benefit for the management of their illness.”