In the most comprehensive study of COVID-19 pediatric patients to date, a research team led by HMS scientists at Massachusetts General Hospital has found that children may play a larger role in the community spread of COVID-19 than previously thought.

The researchers found that infected children, even those with mild or no symptoms, carried high levels of the virus in their respiratory secretions, especially in the first two days of symptoms, and that age did not affect the ability to carry high amounts of virus. The higher the level of virus a person carries, known as the viral load, the greater the risk of transmitting the virus to others.

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. They also 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, the lower levels did not correlate with decreased viral load. According to the researchers, this suggests that children can carry a high viral load, and thus remain contagious, regardless of their susceptibility to developing COVID-19 infection.

For the study, the researchers enrolled 192 participants who were 22 years old or younger and measured viral load and antibody response in three cohorts within each group: healthy children, children with acute SARS-CoV-2 infection, and a smaller number of children with multisystem inflammatory syndrome in children (MIS-C), a multiorgan, systemic infection that can develop in children with COVID-19 several weeks after infection.

Yonker LM et al., The Journal of Pediatrics, August 2020