Covid-19 has been disruptive and bewildering for everyone, but especially for children. In the UK and in most US states, schools closed in March. Many of them will keep their doors shut until the fall. That’s six months without the normality of a school day, not to mention a significant break without any formal education for the many children who cannot access online classes.
It’s a global issue. Schools have had to close in 191 countries, affecting more than 1.5 billion students and 63 million teachers, according to the United Nations. But in many countries, schools are now cautiously reopening: in Germany, Denmark, Vietnam, New Zealand, and China, children are mostly back behind their desks. These countries all have two things in common: low levels of infection and a reasonably firm ability to trace outbreaks.
What about the UK or the US, where the number of cases is relatively high and tracing systems are still in the early stages? How will we know when it’s safe for children to return? There can never be a cast-iron guarantee. But for parents to be able to gauge the level of risk, there are three questions that need answering. How susceptible are children to covid-19? How badly does it affect them? And do they spread it to others?
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We know that children are less likely to catch covid-19 than adults. They’re about half as likely, to be precise, according to a recent study by the London School of Hygiene & Tropical Medicine (LSHTM) using data from China, Italy, Japan, Singapore, Canada, and South Korea, published in Nature Medicine. A survey of 149,760 people with covid-19 by the US Centers for Disease Control and Prevention found that children 17 and under, who make up 22% of the US population, account for fewer than 2% of confirmed infections across the United States.
These findings were supported by a meta-analysis of 18 studies carried out by researchers at University College London, which found that under-18s were 56% less likely to catch coronavirus from an infected person than adults. On the flip side, children are likely to have more close contact with others than adults do, especially in a school, which could potentially mitigate the protective benefit they get from being less likely to catch the virus in the first place. Even so, the numbers look promising.
If children do become infected in spite of this, how badly does it affect them?
The LSHTM study suggests that when children catch covid-19, they usually get very mild effects. Only one in five of those aged 10-19 had any clinical symptoms, compared with 69% of adults over 70. Children are extremely unlikely to die from coronavirus: during the peak nine weeks of the pandemic in England and Wales, just five children 14 and under died, out of a population of almost 11 million in that age group, according to official data analyzed by David Spiegelhalter, a statistician at Cambridge University. A preprint in the journal Public Health found that across seven countries up to May 19, there were 44 covid-19 deaths out of over 137 million children 19 and under. That’s a rate of less than 1 in 3 million. There is an unpleasant new covid-linked inflammatory syndrome in children similar to Kawasaki disease, but it’s extremely rare. “I think there have been fewer than 500 cases reported worldwide,” says Tina Hartert, a medicine professor at the Vanderbilt Institute for Infection, Immunology, and Inflammation in Nashville, Tennessee. The message seems to be that parents should not worry unduly about what might happen to their kids should they catch the virus.
The final crucial question: to what extent do children spread the coronavirus once infected? “If you look at the peer-reviewed literature, it’s very mixed. The simple answer is we don’t know,” says Jeffrey Shaman, an infectious diseases expert at Columbia University. A nine-year-old boy with coronavirus in the French Alps in February did not transmit the virus to anyone else despite exposure to more than 170 people, including close contact within schools. However, we shouldn’t read too much into a study of one. On the other hand, researchers from Berlin University tested 3,712 covid-19 patients, 127 of whom were under 20, and concluded that children can carry the same viral load as adults, which seems to correlate with infectiousness.
One of the biggest fears is that a child could pick up the coronavirus at school and then bring it home to Grandma. “The risk to the kids is low, and it’s not bad for me or my partner, but I do worry about them going back to school and then seeing my parents,” says Kirsten Minshall, a father of two boys aged 9 and 11 who lives in a seaside town in Kent in the UK.
It is possible for children to introduce covid-19 into their household—a study from China identified three occasions when a child under 10 was the “index case” in a home. But it seems to be rare.
The crux of the issue is data, or more precisely a lack of it. Because children are less likely to catch covid-19, and are likely to have milder symptoms if they do, they are less likely to be seen by doctors or tested. That means high-quality, reliable data on this question is hard to come by.
A large National Institutes of Health–funded study in the US that launched last month should help. It’s going to test nasal swabs from nearly 2,000 families in 10 cities every two weeks. The aim is to work out what role children play in transmission, says Hartert, who is leading the study. Enrollment has just finished, and she expects the first results within weeks.
Population-wide serological surveys—which test for the presence of antibodies against covid-19 in blood samples—will also help plug the data gap. Studies comparing areas where schools have reopened and those where they have not could be hugely helpful, too. If it ends up being the case that children are less susceptible to infection, that suggests closing schools won’t be a very important way to reduce transmission across society, says Rosalind Eggo, an infectious disease modeler at LSHTM, who was involved in the study. However, she warns that it’s tricky to disentangle the closure of schools from all the other actions that were taken at the start of the pandemic.
“It’s very difficult to work out what happened to transmission when schools closed, because that happened at the same time as a lot of other interventions, like a general lockdown, distancing, and increased hygiene,” she says.
But none of this addresses a major group, without which no school can function: teachers.
“Some teachers will be elderly, and there’s no easy answer for them. They’re incredibly high risk,” says Hartert. Many of the schools that have reopened around the world have introduced distancing measures and schedules that minimize contact between school groups.
“I’m less afraid teaching than I am going to the supermarket,” says Marleen Slingenbergh, the head of biology at Alexandra Park School in London, where some schools have reopened for a small proportion of their students. She says that’s because the school has prioritized safety—students have to sanitize their hands between lessons, teachers are required to stay at least two meters away from students at the front of the class, and there are strict “one at a time” bathroom policies, for example.
That said, the majority of students haven’t returned yet. Slingenbergh fears it won’t be possible to maintain the safety measures when school returns in full in September. “With one week on, one week off, it’s possible. When we have 1,600 students, it will be tricky, especially during the changeover between lessons,” she says.
Ultimately, the crucial thing for schools may be their ability to respond flexibly—closely monitoring for any potential outbreaks and quickly closing when necessary.
There is, understandably, a lot of pressure from parents to keep their children safe, and many are still not comfortable with sending them back to school, says Slingenbergh. But most of them recognize it’s a delicate balance. “It’s all about weighing up the risks of covid, the kids getting proper schooling, and looking after their mental health,” Minshall says.