Fewer children seem to get infected by the coronavirus than adults, and most of those who do have mild symptoms, if any. But do they pass the virus on to adults and continue the chain of transmission?
The answer is key to deciding whether and when to reopen schools, a step that President Trump urged states to consider before the summer.
Two new studies offer compelling evidence that children can transmit the virus. Neither proved it, but the evidence was strong enough to suggest that schools should be kept closed for now, many epidemiologists who were not involved in the research said.
Many other countries, including Israel, Finland, France, Germany, the Netherlands and the United Kingdom have all either reopened schools or are considering doing so in the next few weeks.
In some of those countries, the rate of community transmission is low enough to take the risk. But in others, including the United States, reopening schools may nudge the epidemic’s reproduction number — the number of new infections estimated to stem from a single case, commonly referred to as R0 — to dangerous levels, epidemiologists warned after reviewing the results from the new studies.
In one study, published last week in the journal Science, a team analyzed data from two cities in China — Wuhan, where the virus first emerged, and Shanghai — and found that children were about a third as susceptible to coronavirus infection as adults were. But when schools were open, they found, children had about three times as many contacts as adults, and three times as many opportunities to become infected, essentially evening out their risk.
Based on their data, the researchers estimated that closing schools is not enough on its own to stop an outbreak, but it can reduce the surge by about 40 to 60 percent and slow the epidemic’s course.
“My simulation shows that yes, if you reopen the schools, you’ll see a big increase in the reproduction number, which is exactly what you don’t want,” said Marco Ajelli, a mathematical epidemiologist who did the work while at the Bruno Kessler Foundation in Trento, Italy.
The second study, by a group of German researchers, was more straightforward. The team tested children and adults and found that children who test positive harbor just as much virus as adults do — sometimes more — and so, presumably, are just as infect
