The Lurking Mystery of the Pandemic: Why Is It Gentler on Children?
WHY YOU SHOULD CARE
Answering these questions could be key to decoding when it’s safe to reopen schools and public spaces.
When a 6-month-old baby was admitted to a California hospital last month with a fever and a blotchy rash, doctors diagnosed a classic case of Kawasaki syndrome.
The inflammatory condition that causes swelling in the blood vessels affects approximately 1 in 200 children in the United States, with telltale signs of bloodshot eyes and cracked lips. So it came as a huge shock to the staff at Lucile Packard Children’s Hospital at Stanford when the infant tested positive for coronavirus.
“It came out of the blue,” says Dr. Dominique Suarez, who treated the child. “We don’t understand much about COVID-19 in children. Is this association a manifestation of the virus?”
Suarez’s observation, which has been repeated in dozens of hospitals around the world, has exposed one of the significant number of unknowns about a virus that leaves the vast majority of children relatively unscathed.
We don’t know what’s going on with the children. They don’t get sick at all, and if they do they’re only mildly sick.
Isabella Eckerle, Geneva Centre for Emerging Viral Diseases
Numerous studies have found that the virus is a mild disease for children. In one of the largest studies, conducted by doctors in Shanghai, 94 percent of children with the virus had an asymptomatic, mild or moderate illness. A separate review by the Karolinska Institute in Sweden found that children accounted for fewer than 5 percent of diagnosed COVID-19 cases globally. Of 2,572 infected children analyzed by the Centers for Disease Control and Prevention, 5.7 percent were hospitalized and three died.
But why children exhibit such mild forms of a virus that has killed 265,000 people globally remains unclear. “Right now it’s still a big mystery,” says Dr. Isabella Eckerle, a virologist at the Geneva Centre for Emerging Viral Diseases. “We don’t know what’s going on with the children. They don’t get sick at all, and if they do they’re only mildly sick.”
One reason some adults become seriously unwell with the virus is because their body triggers a huge immune response — a so-called cytokine storm — that can affect the heart and lungs.
“Imagine you have a couple of thieves coming into a village and you bring in an army and some cannons to fight them,” explains Dr. Gary Wong, a professor of pediatrics at the Chinese University of Hong Kong. “You get rid of the thieves but destroy the village.”
Children’s bodies rarely respond this way and seem better able to “strike the right balance” between effectively fighting disease and damaging the body, Wong says.
Why children and adults respond differently remains unclear. One theory is that children are more likely to be exposed to relatively benign coronaviruses at school or day care, and so they confront COVID-19 with a more effective response.
Yet in an anomaly that underlines the complexity of coronavirus, the massive inflammatory response of the tiny minority of children who develop Kawasaki syndrome appears to contradict the relatively benign immune response in the vast majority of children with the illness.
The lack of clarity on how the virus affects children has come into focus as governments around the world contemplate whether to reopen schools to ease the lockdown.
In the early days of the outbreak, policymakers believed the virus could spread easily among young people, like any other infectious disease, and so schools were closed around the world to limit transmission.
But recent analysis into how the virus spreads in schools and households has suggested this may not be the case. One Australian study found 18 coronavirus-positive students did not infect any of the 735 children and 128 staff they were in close contact with at school. And a study from China found children had been the index, or first case, of COVID-19 in fewer than 10 percent of households, compared with 54 percent in a comparable study of swine flu.
Other studies, including one co-authored by Eckerle into viral loads — the number of particles carried by a person with the virus — have reached different conclusions. Generally, a high viral load means people have more serious symptoms and shed more virus particles, making them more infectious. Yet Eckerle’s team found little difference between the viral loads in children and those in adults despite the former generally having a relatively mild form of the disease.
A separate study at Charité-Universitätsmedizin Berlin, one of Europe’s largest university hospitals, examined thousands of swabs and concluded that children “may be as infectious as adults.” The study highlighted concerns that asymptomatic children who did not conform to social distancing and hygiene rules could easily spread the virus, and cautioned against schools reopening.
“Transmission potential in schools and kindergartens should be evaluated using the same assumptions of infectivity as for adults,” wrote the authors, who included Dr. Christian Drosten, the institute’s director.
Such conflicting science makes it extremely difficult to make informed decisions. The rate of COVID-19 infection rose in Denmark after its schools and kindergartens reopened last month.
“We really need those basic facts about infectiousness in children,” says Jennifer Dowd, deputy director of the Leverhulme Centre for Demographic Science at Oxford.
Wong says a more comprehensive understanding of how the virus affects children is meant not just to protect young people: It will help in the pandemic fight more generally by increasing knowledge of the illness. “We want adults to react to the virus the way that children do,” he says.
“All of us are in a learning curve because we’ve never seen a virus behave like this,” Wong says. “We’re learning bit by bit.”
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