Children may play a larger role in spread of virus
As schools reopen in parts of the United States, a paper published Thursday found that some children have significantly higher levels of virus in their airways than the most severely ill adults — suggesting their role in community spread may be larger than previously believed.
The study in The Journal of Pediatrics comes on the heels of two others that offer insights about children and COVID-19 transmission. On July 30, researchers reported in JAMA that children younger than 5 with mild or moderate illness have much higher levels of virus in the nose compared to older children and adults. Shortly before that, investigators in South Korea found in a household study that older children passed on the virus as readily as adults, while younger children did not.
Alessio Fasano, a physician at MassGeneral Hospital for Children and one of the new study’s authors, said that because children tend to exhibit mild symptoms or none at all, they were largely ignored in the early part of the outbreak and not tested. But they may have been acting as silent spreaders all along.
“Some people thought that children might be protected,” Fasano said. “This is incorrect. They may be as susceptible as adults — but just not visible.”
Lael Yonker, lead author and a pediatric specialist at Massachusetts General Hospital, expressed surprise that the viral loads of hospitalized adults who are usually kept isolated may be “significantly lower than a ‘healthy child’ who is walking around with a high SARSCoV-2 viral load.”
Since the virus first appeared, its impact on children has been among the most baffling. Time has confirmed that most children appear to have mild disease or no symptoms, but why that is remains a mystery.
The new paper provides one of the most detailed looks at the immune reaction in children exposed to the coronavirus. Of the 192 pediatric patients seen at Boston’s Massachusetts General Hospital and Mass General Hospital for Children, 49 were diagnosed with acute infection and another 18 with MIS-C, the multi-inflammatory syndrome linked to the virus. The mean age of the children in the study was 10 years old. The percentage of children who tested positive for the virus was about 25 percent, Fasano said, as compared with about 20 percent for adults.
Among the other preliminary findings: Age did not impact viral load (or amount of virus present) and that viral load appeared especially high about two days into the infection.
Another eye-opening finding involves immune receptors known as ACE2 that the virus uses to invade the body. Scientists had hypothesized that because children may have lower numbers of the receptors, they may be less likely to be infected or to transmit the virus. The data confirmed that younger children do have lower numbers of receptors than older children and adults — but that this did not seem to be related to viral load.
A separate paper out this month from Children’s National Hospital in Washington, D.C. of 177 children and young adults with SARS-CoV-2 infections between March 15 and April 30 found that the youngest and oldest children were more likely to be hospitalized and the oldest were most likely to require critical care.
Roberta DeBiasi, an infectious disease expert, and her co-authors noted that asthma was the most common underlying diagnosis in the children infected — but that they were not overrepresented in those who were hospitalized or critically ill.
Bill Kapogiannis, a National Institutes of Health researcher in pediatric infectious diseases who was not involved in Fasano’s study, called those findings “potentially concerning.”
“It’s interesting, but we need a bigger cohort to make strong conclusions,” he said.
Several such efforts are in the works. NIH has pledged as much as $20 million over four years to study biomarkers and other indicators that will characterize how the disease progresses in children.