To your Health! The kids are (mostly) all right; grown-ups are the germ factories

I used to call my kids “plague vectors.” When they were in elementary school, they constantly brought home various flavors of illness: coughs, runny noses, the dreaded tummy bug. Kids can’t keep their grubby little hands out of their mouths, ears, or noses. They gnaw on their clothing and fiddle with their friends’ stuff. They hug cheek-to-cheek. Given all that, you’d think that even Harvard’s carefully masked and distanced elementary-school classes would be cesspools of coronavirus. And you’d be wrong.

To many anxious people’s surprise, when schools opened this past semester, superspreading events failed to materialize. And the few big outbreaks that did occur—notably in Israel in May, and Dallas, Georgia, in August—happened at high schools in which anti-COVID-19 measures like masking, distancing, and improved ventilation weren’t in place. What happened to the little snot-ridden plague vectors?

Younger kids get and spread COVID-19 less

The obvious explanation, in Harvard at least, is that elementary school kids—and high school kids, too—aren’t allowed in school if they have any sign of illness. So it’s not surprising that they aren’t spreading disease in their classrooms. But aside from that, some studies show that when it comes to COVID-19, children are not the germ factories we might expect them to be. Grown-ups are.

We know that for sure because researchers in Iceland have been tracking every single person in the nation who’s been quarantined because of possible COVID-19 exposure. As National Geographic reported on the Iceland study in December: “Children under 15 were about half as likely as adults to be infected, and only half as likely as adults to transmit the virus to others. Almost all the coronavirus transmissions to children came from adults. ‘They can and do get infected and transmit to others, but they do both less frequently than adults,’ says Kári Stefánsson, the chief executive of deCODE,” a biopharmaceutical company.

Why on earth should that be the case? Scientists don’t yet know all the reasons, but the answer probably lies in a nest of interrelated factors. Kids’ noses have fewer ACE2 receptors than adults’ do, and the virus needs to attach to that receptor to get into cells. Kids’ T cells, which learn to recognize and respond to microbial invaders, haven’t seen as many invaders as adults’ T cells have; maybe having so many “naïve” T cells makes kids better at responding to a brand-new virus. Maybe the very fact that kids harbor so many common-cold-causing coronaviruses gives them an advantage over this one particularly nasty coronavirus. Maybe it’s all those things put together, plus other stuff scientists haven’t figured out yet.

Whatever the reason, the scientific consensus now is clear: Something changes around the time of puberty that makes older children act more like adults, COVID-19-wise. Brown University professor of economics Emily Oster highlighted this fact using data from New York state. She showed that the rate of coronavirus infection in elementary schools was consistently lower than it was at the middle- and high-school level, where it mirrored the rate of coronavirus in the community.

That last point is super important, by the way: The rate of COVID-19 in middle and high schools mirrors the rate of coronavirus in the community; it doesn’t exceed that rate. That’s what tells you that middle and high schools aren’t superspreading environments. If they were, Oster explained, the rate of COVID-19 there would be higher than in the community as a whole.

To keep schools safe, do what schools do

But wait—why didn’t those New York high schools have big outbreaks, with almost-grownups sharing classrooms for hours? In part because the infection rate in the area was low. If the virus is running rampant in the community, it’ll cause problems in the schools, too.

But a lot of the credit goes to the COVID-19 big four. Masking. Ventilation. Hand hygiene. And maybe most important, distancing. Which, incidentally, isn’t possible if schools are completely full. So, even though high schools are filled with rebellious teens who we might expect to stick their noses out of their masks just to irritate their teachers, the evidence shows they aren’t doing that in school. Or at least not enough to make a difference.

Outside of school, it’s another story. As a report for the Association of American Medical Colleges pointed out, “Students and staffers who have tested positive for the coronavirus usually contracted the virus out of school.” That’s why experts from the CDC, the Rockefeller Foundation, and the American Federation of Teachers have all called for ongoing COVID-19 screening at schools: to keep the infections contracted in the community out of school buildings.

Kids get COVID-19 out in the community, when they’re not under teachers’ watchful eyes, and when they’re surrounded by the real plague vectors: the grown-ups.

Which brings up one more possible reason why young children get and spread COVID-19 less frequently than everybody else does: their behavior. Kids go out into the community as little as possible; many go nowhere but to school and back home. When they do go to school, they’re required to mask up, stay apart from one another, and wash their hands, and they do it. They don’t go to restaurants and eat shoulder-to-shoulder with their buddies. They don’t go to the gym to work out. When their masks slip below their noses, their teachers call them on it, and they pull their masks up.

Maybe kids get and spread COVID-19 less frequently than everyone else for one good reason: They’re the only ones who consistently follow the rules.
  

Liz Ruark is the founder of covidsafeschools.org and co-chair of COVID-Safe Schools, Harvard Public Schools’ community COVID-19 screening program. She holds a DVM degree from Tufts Cummings School of Veterinary Medicine.