Some medical experts have expressed concern that COVID-19 preventative measures, like masking and remote schooling, are potentially weakening children’s immune systems by shielding them from the usual childhood illnesses.

“There’s a lot of reasons to believe that kids need to be exposed to things to keep their immunity complex, so that should they encounter something very dangerous, they have aspects of their immunity that might cross over and help protect them against those things,” says Sara Sawyer, a professor of molecular, cellular and developmental biology at the University of Colorado Boulder.

At birth, vulnerable infants get antibodies from their mother’s breast milk, which helps protect them until they can build their own immunity. It’s no accident that babies start putting things in their mouths as soon as they gain enough dexterity to pick things up.

“They’re doing that because they’re sampling the environment and building their immunity. That’s an evolutionary trait,” Sawyer says. “They’re exposing their body to germs in a certain, level way to build their immunity. So, some people would argue that childhood illnesses, like colds and stomach bugs, build our immunity so that when more dangerous things come along, we’re prepared and we don’t get as sick from those more dangerous things.”

Even before the pandemic, epidemiological evidence suggested that children in more developed countries, where handwashing and the use of sanitizer are more prevalent, might have less-developed immune systems compared to kids in developing nations who are routinely exposed to more bacteria, viruses and allergens. This makes kids in more industrialized countries more vulnerable to developing autoimmune diseases, according to what’s known as the “hygiene hypothesis.”

“The hygiene hypothesis is actually quite controversial because it’s thought that our exposure to microbes isn’t the only factor,” says Cody Warren, a virologist and immunologist who is a postdoctoral fellow at the University of Colorado Boulder. “A lot of this could also be dictated by genetics, diet, and the environment that we live in. That also shapes our immune system… it’s a real multifactorial thing that we can’t fully account for just by wearing masks. There are other things that go into that equation.”

Warren, the father of three young children, says spending lots of time outdoors is one way to balance the negatives of isolation.

“Just exploring microbes in the environment also is benefiting [and] training our immune system,” Warren says. “Our immune systems get trained through the foods that we eat, which also have microorganisms on them. And so, despite the fact that we’ve kind of been hunkered down a little bit, I do feel that our immune systems will catch up.”

There are other things parents can do, he says, to boost their children’s immune systems during pandemic times.

“One of the most important things you can do is just to stay up to date on vaccines. That’s one of the best ways that we have to train our immune systems,” Warren says. “But also, equally important is making sure our children have a good diet and they regulate stress. It’s been well documented that both of those — having a good diet, a less stressful environment — can have a positive impact on our immune system.”

Once public health officials say masks are no longer necessary, Sawyer thinks pointing out the positives of putting our masks away could reassure hesitant parents who worry about their children getting sick.

“Maybe we should have a public conversation about the possible reasons to take that mask off, if they are in school, and get back to the normal repertoire of relatively safe childhood illnesses,” she says. “The plus side of childhood illnesses is that they can build up that hornet’s nest of immunity that could protect kids against new things that then come along.”
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