Why do children fare better than adults against COVID-19? Their innate immune response stops the virus earlier, study says.

Since the start of the pandemic, health experts have offered numerous theories to explain why children fared better than adults against the coronavirus.

Some thought kids were less likely to come into contact with the virus as schools closed. Others hypothesized they might not have a specific molecule essential for the virus to attach to host cells.

But a new study found children are largelyable to avoid severe disease because a natural part of their immune response stops the virus early in its tracks, according to researchers at the Albert Einstein College of Medicine, Montefiore Health System and Yale University.

“What our data would suggest overall is that when children see the virus they have a very robust innate immune response and our belief is that it seems to be protective (and) stop the virus at first encounter,” said study co-author Dr. Kevan Herold, professor of immunology and internal medicine at Yale University.

The study, published Tuesday in the peer-reviewed journal JCI Insight, involved 12 children and 27 adults seen at the Montefiore Medical Center emergency department who tested positive for COVID-19.

Researchers used nasal swabs for RNA sequencing and found children had higher levels of genes associated with immune cells compared to adults. They also found several protective cytokines, which are proteins secreted by immune cells.

None of the 12 children in the study required oxygen, while seven of the 27 adults did, and four of them died.

The report follows another study conducted by the same authors and published in September that compared blood samples from pediatric and adult COVID-19 patients. Although researchers found little difference between the blood samples, they foundclues that indicated they would find what they were looking for in nasal swabs.

Based on the two studies, study authors say children have a strong innate immune response that stops the virus early in the upper respiratory tract without allowing it to progress into severe disease. Meanwhile, adults may have to rely on a slower, adaptive immune response that’s triggered later in the disease’s progression.

“Your innate response is not pathogen-specific, it’s more of a response in general when your body sees virus or any other pathogen … it doesn’t have to match exactly that virus,” said Dr. Betsy Herold, chief of the division of pediatric infectious diseases and vice chair for research in pediatrics at Albert Einstein College of Medicine and Montefiore Health System, who co-authored the study with her husband. “The kids make more of the innate response and, therefore, they don’t need as much of this robust adaptive response.”

Although children may have a natural immune response to fight off infection, BetsyHerold says it’s still important for them to get vaccinated when the COVID-19 vaccine becomes available. Pfizer’s vaccine with German partner BioNTech is authorized now for 16 and 17 year-olds, and vaccines for younger children are expected later this year.

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Having an innate immune response to the coronavirus doesn’t fully protect children from getting sick, she warns. As of April 1, nearly 3.47 million children have tested positive for COVID-19 and more than 280 have died, according to the American Academy of Pediatrics. Although they’re unlikely to develop severe disease, children can still act as a vector and transmit COVID-19 to more vulnerable adults.

Kids who aren’t vaccinated also run the risk of developing multisystem inflammatory syndrome in children (MISC), a rare but dangerous syndrome that causes intense bodily inflammation and can damage the heart, kidneys and other organs, Betsy Herold added.

“Having both a really good innate immune system based on their age combined with adaptive immune responses based on the vaccine is going to put them in the best place they could ever hope to be and really is going to help us get rid of this pandemic,” she said.

Follow Adrianna Rodriguez on Twitter: @AdriannaUSAT.

Health and patient safety coverage at USA TODAY is made possible in part by a grant from the Masimo Foundation for Ethics, Innovation and Competition in Healthcare. The Masimo Foundation does not provide editorial input.

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