Massachusetts General Hospital researchers show children spread virus that causes COVID-19
In the most comprehensive study of COVID-19 pediatric patients to date, Massachusetts General Hospital (MGH) and Mass General Hospital for Children (MGHfC) researchers provide critical data showing that children play a larger role in the community spread of COVID-19 than previously thought, according to a press release from MGH. In a study of 192 children ages 0-22, 49 children tested positive for SARS-CoV-2, and an additional 18 children had late-onset, COVID-19-related illness. The infected children were shown to have a significantly higher level of virus in their airways than hospitalized adults in ICUs for COVID-19 treatment.
“I was surprised by the high levels of virus we found in children of all ages, especially in the first two days of infection,” says Lael Yonker, MD, director of the MGH Cystic Fibrosis Center and lead author of the study, “Pediatric SARS-CoV-2: Clinical Presentation, Infectivity, and Immune Reponses,” published in The Journal of Pediatrics. “I was not expecting the viral load to be so high. 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.”
Transmissibility or risk of contagion is greater with a high viral load. And even when children exhibit symptoms typical of COVID-19, like fever, runny nose and cough, they often overlap with common childhood illnesses, including influenza and the common cold. This confounds an accurate diagnosis of COVID-19, the illness derived from the SARS-CoV-2 coronavirus, says Yonker. Along with viral load, researchers examined expression of the viral receptor and antibody response in healthy children, children with acute SARS-CoV-2 infection and a smaller number of children with Multisystem Inflammatory Syndrome in Children (MIS-C).
Findings from nose and throat swabs and blood samples from the MGHfC Pediatric COVID-19 Biorepository carry implications for the reopening of schools, daycare centers and other locations with a high density of children and close interaction with teachers and staff members. “Kids are not immune from this infection, and their symptoms don’t correlate with exposure and infection,” says Alessio Fasano, MD, director of the Mucosal Immunology and Biology Research Center at MGH and senior author of the manuscript. “During this COVID-19 pandemic, we have mainly screened symptomatic subjects, so we have reached the erroneous conclusion that the vast majority of people infected are adults. However, our results show that kids are not protected against this virus. We should not discount children as potential spreaders for this virus.”
In another breakthrough finding from the study, the researchers challenge the current hypothesis that because children have lower numbers of immune receptors for SARS-CoV2, this makes them less likely to become infected or seriously ill. Data from the group show that although younger children have lower numbers of the virus receptor than older children and adults, this does not correlate with a decreased viral load. According to the authors, this finding suggests that children can carry a high viral load, meaning they are more contagious, regardless of their susceptibility to developing COVID-19 infection.
