Opinion | Children Aren’t the Big Infection Risk in Schools. Adults Are.

There’s also a natural human error we make when we assume that children are our greatest infection risk. Constant vigilance over masking and distancing is exhausting. It’s understandable that teachers work their hardest to follow best practices when interacting with children, but then let their guard down with their trusted colleagues, with whom they are yearning to have normal social interactions.

I have observed this behavior among staff members at indoor camps this summer while conducting Covid-19 research and in my own workplace, and have heard about it from others. Adults go into break rooms, take off their masks, and spend a little time eating and talking to colleagues — 10 minutes, half an hour. This is when the virus has the opportunity to spread.

Understanding that adults, not children, are the most likely transmission vectors will help teachers and other staff members stay safe by remaining masked when spending time together.

Finally, in our pre-Covid-19 mental model, we think of high school students as being less of a germ source than elementary-school children. Teenagers tend to get sick less often and are better able to contain their runny noses and coughs.

However, the global data show that outbreaks are bigger in high schools than in elementary schools and that transmission is most likely happening not only among adults in these schools, but among students, too.

This is evidenced by two studies in Oise, one of the most heavily affected areas of France, where around 10 percent of people in the community were infected. The study of several elementary schools found that 9 percent of students and 7 percent of teachers were infected (and the data suggested that the children got Covid-19 from a household contact, not from school). But the second study, of a high school, found that a whopping 43 percent of teachers and 38 percent of students had been infected.

An Israeli middle and high school experienced an outbreak in May, soon after schools reopened. More than 150 students and staff members were infected. But there’s a lesson here: It happened during a heat wave, when windows were closed and air-conditioners turned on, and the school was not enforcing masking or physical distancing.