Silent Spreaders?

Children may play a larger role in community spread of COVID-19 than previously thought


This article is part of Harvard Medical School’s continuing coverage of medicine, biomedical research, medical education and policy related to the SARS-CoV-2 pandemic and the disease COVID-19.

In the most comprehensive study of COVID-19 pediatric patients to date, Harvard Medical School researchers based at Massachusetts General Hospital and Mass General Hospital for Children provide data showing that children may play a larger role in the community spread of COVID-19 than previously thought.

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The study, published in The Journal of Pediatrics, examined 192 children, adolescents and young adults who came to hospitals with symptoms of or suspected exposure to COVID-19. In this group, 49 individuals tested positive for SARS-CoV-2, the virus that causes COVID-19, and an additional 18 had a late-onset COVID-19-related illness.

The researchers found that infected children carried high levels of the virus, or viral load, in their respiratory secretions, even children with mild or no symptoms. Age did not affect the ability to carry a high viral load, which is associated with increased risk of transmitting the virus to others.

Notably, the team found that infected children in the asymptomatic or early infection phase had significantly higher viral loads than hospitalized adults with severe COVID-19.

The results carry implications for the reopening of schools, daycare centers and other facilities with a high density of children and close interaction with teachers and staff members, the authors said.

“I was surprised by the high levels of virus we found in children of all ages, especially in the first two days of infection,” said lead study author Lael Yonker, HMS assistant professor of pediatrics at Mass General.

“I was not expecting the viral load to be so high,” said Yonker, who is co-director of the MGH Cystic Fibrosis Center. “You think of a hospital, and of all of the precautions taken to treat severely ill adults, but the viral loads of these hospitalized patients are significantly lower than a ‘healthy child’ who is walking around with a high SARS-CoV-2 viral load.”

In addition, the team found that although younger children had lower levels of ACE2—the receptor protein that SARS-CoV-2 targets to enter human cells—than older children and adults, this did not correlate with decreased viral load.

This suggests that children can carry a high viral load regardless of their susceptibility to developing COVID-19 infection, according to the authors.

“This study provides much-needed facts for policymakers to make the best decisions possible for schools, daycare centers and other institutions that serve children. Kids are a possible source of spreading this virus, and this should be taken into account in the planning stages for reopening schools.”

Alessio Fasano