Kids aren't viral vectors. Really.

As a paediatrician, I love treating children, but I am well aware that the urgent care clinic where I work is not germ-free. Inevitably, I catch the occasional bug from a kid with a runny nose and a cough.

When the coronavirus pandemic began, I worried that I would treat children who were asymptomatic or mildly ill ("just a cold"), then get the virus myself and spread it to my parents or friends. Many teachers who are about to return to school have the same worries.

But we have known for months that the coronavirus does not act like normal cough and cold viruses that we often catch from children. In a surprise to pediatricians, teachers and parents alike, the virus behaves the opposite of what we are used to. Children and adolescents do not seem to get sick with Covid-19 as frequently as adults. And children, especially elementary school-aged children, do not seem to transmit it effectively to one another, nor to adults.

This has been documented in countries around the world, including Greece, Switzerland and Australia. Even when schools are open, most children who get ill are found to have been infected by someone in their household, not from a school contact.

That study that says kids have more virus didn’t measure transmission

These data put into context a recent study of 145 children and adults in Chicago in March and April that was widely reported. It found that young, symptomatic children had more of the virus in their noses than adults. Some speculated that this meant that the children could spread it as easily as adults. But the study was small and didn't actually measure transmission; we learn much more useful information from the global data, which show it is unlikely that the increased viral load translates to increased infectiousness.

We understand this; we've heard it before. And yet it's still hard to change that deeply rooted idea of the snotty-nosed kid as the germ propagator.

As we consider reopening schools, and elementary schools in particular, we need to reframe this mental model. The real risk of transmission in elementary schools is not the kids; it's the adults.

It’s the adults, not the kids, that we need to worry about being virus vectors

Why is this important? It means we have much more control over transmission than we would with another kind of virus, because teachers and other school employees can control and modify their behavior in ways that children cannot.

We know much more about the coronavirus than we did in March, when many schools first closed their doors. Our guiding principles to stop its spread are mask-wearing, physical distancing, hand washing, small classes and good ventilation (open windows instead of recycled air). Adults can make sure these principles are maintained.

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 behaviour 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.

Research shows older students are also spreaders

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.

This is not to dismiss the risk of kids getting infected - obviously it happens. Around 100,000 children and young adults tested positive for the virus in the last two weeks of July in the United States.

High schools should be treated like adult workplaces

Taken together, the data tell us that high schools should be treated more like adult workplaces - with many studying from home for a substantial proportion of time. Hybrid curriculums are most likely going to be an important part of middle-school life as well, though more information is still sorely needed on Covid-19 among middle schoolers.

But when it comes to elementary school, there are ways to reopen schools safely for in-person instruction. We should put aside the specter of the 6-year-old viral vector still trying to figure out how to use a tissue, and realize that we can control transmission if we follow the public health principles outlined above, on masking, physical distancing and more. This will require real effort. But it can be done.