A study introduced an unwelcome wrinkle into this smooth narrative, infected children have at least as much of the coronavirus in their noses and throats as infected adults.
Children younger than the age of 5 may host to 100 times as much of the virus in the upper respiratory tract as adults, according to research.
The study does not necessarily prove that children are passing the virus to others. Still, the findings should influence the debate over reopening schools, several experts said.
“The school situation is so complicated. There are many nuances beyond just the scientific one,” said Dr. Taylor Heald-Sargent, a pediatric infectious diseases expert at the Ann and Robert H. Lurie Children’s Hospital of Chicago, who led the study, published in JAMA Pediatrics.
“But one takeaway from this is that we can’t assume that just because kids aren’t getting sick, or very sick, that they don’t have the virus,” she added.
Still, experts were alarmed to learn that young children may carry significant amounts of coronavirus.
According to Stacey Schultz-Cherry, a Virologist at St. Jude Children’s Research Hospital, “I’ve heard lots of people saying, ‘Well, kids aren’t susceptible; kids don’t get infected.’ And this clearly shows that’s not true.”
“I think this is an important, really important, first step in understanding the role that kids are playing in transmission,” she said.
Dr. Heald-Sargent and her team analyzed samples collected with nasopharyngeal swabs between March 23 and April 27 at drive-through testing sites in Chicago and from people who came to the hospital for any reason, including symptoms of COVID-19.
They looked at swabs taken from 145 people: 46 children younger than age 5; 51 children aged 5 to 17; and 48 adults aged 18 to 65. To forestall criticisms that really ill children would be expected to have a lot of the virus, the team excluded children who needed oxygen support. Most of the children in the study reported only a fever or cough.
To compare the groups fairly, the team included only children and adults who had mild to moderate symptoms and for whom they had information about when symptoms began. She left out people who didn’t have symptoms and who did not remember when they had started to feel ill as well as those who had symptoms for more than a week before the testing.
The results confirmed that older children and adults had similar CTs, with a median of about 11 and ranging up to 17. But, children younger than the age of 5 had significantly lower CTs about 6.5.
The upper limit of the range in these children was a CT of 12, however, still comparable to those of older children and adults.
“It definitely shows that kids do have levels of a virus similar to and maybe even higher than adults,” Dr. Heald-Sargent said. “It wouldn’t be surprising if they were able to shed” the virus and spread it to others.
The experts all emphasized that the findings at least indicate that children can be infected. Those who harbor a lot of viruses may spread it to others in their households or to teachers and other school staff members when schools reopen.
Many school districts are planning to protect students and staff members by implementing physical distancing, cloth face coverings, and hand hygiene. But it’s unclear how well staff members and teachers can keep young children from getting too close to others, said Dr. Jason Kindrachuk, a virologist at the University of Manitoba.