A new, unsettling study on children and the coronavirus pandemic has just been published as countries around the world reopen kindergartens and school classrooms. The study's findings are sure to further fuel already heated debates over the risk of infection in institutions of learning.

Doctors at the Children's National Hospital in Washington, DC have found that infected children can spread the SARS-CoV-2 virus for weeks even though they themselves show no COVID-19 symptoms. That means that children with only mild symptoms, or none at all, can unknowingly infect people around them.

In an earlier study, researchers in Boston showed that children and youths they observed had surprisingly high viral loads.

Read more: Learning pods and cardboard cubicles: US schools adapt to the pandemic

Asymptomatic children spreading the virus?

The new study, which was published on August 28 on the website of the medical journal JAMA Pediatrics, was conducted by Roberta L. DeBiasi and Meghan Delaney, who analyzed data from 91 children in 22 hospitals across South Korea. "Unlike in the US health system, those who test positive for COVID-19 in South Korea remain in the hospital until they have completely recovered from their infection," says DeBiasi.

According to the study, roughly 22% of the children developed no symptoms throughout their infection, 20% began asymptomatic but later developed symptoms, and 58% tested symptomatic. The study also showed great differences in the length of time children remained symptomatic, ranging from three days to three weeks. One-fifth of the asymptomatic patients and roughly half of the symptomatic patients were still passing on the SARS-CoV-2 virus three weeks after initial infection — though this did not directly reflect their contagiousness.

The authors readily admit that there is still much to be learned about the role of children and youths in the spread of the coronavirus, and that their findings will further fuel that debate.

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Outsized viral load for kids?

Researchers in Boston, meanwhile, found surprisingly high viral loads among the youngest patients they observed. For their study, they took nose and throat swabs from 49 children and youths under the age of 21. The study found far more SARS-CoV-2 virus presence among them than among adults being treated in intensive care units for COVID-19.

According to the Boston study, which was published on August 1 in the periodical The Journal of Pediatrics , scientists found far fewer ACE-2 receptors among smaller children than in youths and adults. Those receptors are thought to be SARS-CoV-2's gateway into the body's cells.

Read more: Coronavirus: German parents angry at order to isolate their children

Tiny 'superspreaders'? 

The role of children and youths in the spread of the coronavirus has been hotly debated since the first infections were registered. One thing is clear, children and youths can infect others. It is also clear that infected children and youths often show few or no signs of being ill. And it is also just as clear — though most people prefer not to talk about this — that children and youths can also die or suffer lasting damage as the result of a COVID-19 infection.

That doesn't automatically mean that all children and youths are potential "superspreaders," driving infection rates around them. Still, children and youths — through kindergarten, school, friends and sports — often have far more social interaction than adults. The past few months have also shown that young people are just as likely as adults to ignore social distancing and hygiene rules if they are not compelled to do otherwise.

Amid a flood of returning vacationers, along with parties and crowded events, German infection rates are now the highest they have been since April. A great number of those testing positive for COVID-19 now are young, driving down the average age of infection to the lowest figure registered since the pandemic began.

Still, despite high viral loads and the ability to pass on the virus for weeks — even if a child is asymptomatic — young people can still act decisively to stop the spread of infection.

Read more: German students defy coronavirus to study abroad

What does it mean for kindergartens and schools?   

The end of summer has seen infections rising across Germany and many other countries. Nevertheless, kindergartens, schools and other learning institutions are opening their doors, not just to provide relief to parents, but even more so, for the well-being of children. 

Compulsory face masks, physical distancing, hygiene rules and set study groups can all reduce the risk of spread. That's the consensus, but just how to deal with such issues, as well as how often classes should be held online or in person, remains open to interpretation in many countries.

In order to detect potential infection clusters and avoid large-scale school closings, infections among asymptomatic children and youths must be pinpointed early and the child isolated.

These latest studies will no doubt lead to a reassessment of the need to regularly test teachers, but also the question of whether testing should be carried out only on those students exhibiting acute respiratory infections, or rather on a far greater percentage of children.