Children's resistance to coronavirus might help us understand how to stop it

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As the novel coronavirus continues to sweep across the globe— in what the World Health Organization officially deemed a pandemic on Wednesday — one subset of the population has largely evaded harm: children. But why doesn’t coronavirus seem to affect children? The answer may help us tease apart its modus operandi, which can, in turn, provide insights into how to beat it, the Washington Post reports.

According to the WHO, only 2.4% of reported cases in China were kids, and there have been no reported cases in the country of a young child dying of the disease caused by the novel coronavirus, or COVID-19, per the Post. Yet people over 80 in China have an estimated death rate of 21.9%, the WHO found. Another study observed that those between the ages of 10 and 39 have a death rate of only 0.2%, and there were virtually no severe symptoms or deaths in younger age groups. This stands in sharp contrast to the seasonal flu and many respiratory diseases, which poses the greatest risk to young children and seniors.

Frank Esper, a pediatric infectious disease specialist at Cleveland Clinic Children’s, told the Post that unravelling why the novel coronavirus spares children could shed light on why it’s more dangerous in other age groups. He and other medical experts are investigating whether it may have to do with pollution damage built up in people’s lungs over time, or underlying conditions like hypertension, which few children have, among other lines of inquiry.

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The SARS coronavirus outbreak in the early aughts and the MERS coronavirus, first reported in 2012, have also left children largely unaffected, according to the Post. Vineet Menachery, a virologist at the University of Texas Medical Branch, is trying to understand this age disparity by infecting mice with SARS, which is closely related to the novel coronavirus. Baby mice bounced back, but older mice suffered severe damage in their lungs and elsewhere. Menachery associated deaths among older mice with not only weakened immune systems, but an overreaction of their immune systems to the SARS coronavirus — not unlike how people are dying from novel coronavirus infections. But why SARS didn’t kill baby mice remains unclear.

Scientists have yet to solve the puzzle of why coronavirus spares kids, but the fact that it does raises questions of whether the hundreds of school closures across the country are necessary. In fact, it’s been hypothesized that children are less prone to infection. Many epidemiologists, though, believe they’re getting infected as often as adults are — their symptoms are just milder. Indeed, authorities who identified cases in Shenzen, China based on symptoms alone found lower infection rates in children, per data released on March 4 — but the infection rates in children younger than 10 and other age groups was similar among close contacts of confirmed cases, the South China Morning Post reports.

Since kids can spread disease to their family and the community, closing schools can help curb transmission, as well as protect teachers and other adult employees, Caitlin Rivers, an epidemiologist at the Johns Hopkins Center for Health Security, told the Washington Post.

Amid the race to develop vaccines and treatments, understanding how and why the new coronavirus seriously harms some people and not others may seem like an intellectual question rooted mostly in curiosity, but it's important. “There are all these big questions we’re going to want to answer in the long-term if we want to really understand how these coronaviruses work,” Stuart Weston, a virologist at the University of Maryland School of Medicine, told the Post. Later, this understanding could inform not only treatment, but prevention, too.