Since the coronavirus outbreak began, scientists have been trying to work out why children are much less likely than adults to experience severe complications from the infection. Now research suggests that the answer might lie in children’s healthy blood vessels. Children make up only a small proportion of those infected by SARS-CoV-2, the virus that causes COVID-19.
children aged 17 and under, who make up 22% of the US population, account for fewer than 2% of confirmed COVID-19 infections across the United States. And, of 2,572 children included in the survey, only 5.7% went to hospital and only three died.
Many adults with serious COVID-19 experience clotting in their blood vessels, which leads to heart attacks or strokes. The clotting seems to be linked to a malfunctioning endothelium, the smooth tissue that lines blood vessels and normally prevents clotting, says Frank Ruschitzka, a cardiologist at the University Hospital Zurich in Switzerland. Normally, blood clots form only to stop bleeding from an injury, but if the endothelium is damaged, clots can also form.
Endothelium is typically in much better condition in children than adults. “A kid’s endothelium is set up perfectly and then just deteriorates with age,” says Paul Monagle, a paediatric haematologist at the Melbourne Children’s Campus.
Monagle and others think that children’s blood vessels are able to withstand a viral attack than adults. Further support for this theory is the observation that few children with COVID-19 present with excessive clotting and damaged vessels, he says.