One of the few bright spots of the coronavirus pandemic has been among children. Although severe illness and death have occurred, most children are spared the most serious outcomes. And some have no symptoms at all.
The latter group has been of particular interest to researchers and policymakers, who have long sought to quantify how many children are asymptomatic, or “silent carriers” of COVID-19.
New research out of Canada provides one of the clearest estimates to date, finding that one-third of children diagnosed with COVID-19 are asymptomatic. (Previous estimates have suggested the number is anywhere between 16% and 45%.)
The new study included more than 2,400 children who were tested for COVID-19 between April and September.
More than 35% of the children who had coronavirus reported no symptoms.
And while many of the children who tested positive for COVID-19 reported having a cough, runny nose and sore throat, those symptoms were actually more common among children who were negative for COVID-19.
“Having no symptoms does not mean that a child is safe and non-infectious to other classmates,” Dr. Finlay McAlister, an internist with the University of Alberta, Edmonton, and an author on the study, told HuffPost.
“This emphasizes the importance of wearing masks, being socially distant, frequent hand-washing — all of the standard public health advice,” he said.
He added that the study also suggests the screening measures often used in schools and child care settings could be missing a significant chunk of children who are in fact positive for the virus — either because they have no symptoms or because the symptoms they are being asked about are not necessarily indicative of COVID-19.
However, the researchers did find that loss of smell and taste was seven times higher among children who tested positive for COVID-19 compared to those who did not. So it could be a particularly important symptom to screen for.
Ultimately, understanding how common asymptomatic spread is among children may be most important from a public health and infection control perspective.
Elementary schools and day cares do not appear to be the “super-spreaders” they were once feared to be. But they are nonetheless vulnerable to undetected spread of COVID-19 if a significant percentage of children are asymptomatic carriers of the virus.
“Although your kid may be asymptomatic, and you may not have elderly relatives, the kid sitting at the desk next to them may have an immunosuppressed parent or grandparent,” said McAlister.
He noted that his team’s study was done at a time when local schools were closed, so the numbers could look different if a similar study was done while schools are in session. (His team is doing that work now.)
More than 1.3 million children have been diagnosed with COVID-19 in the United States, and the number of new cases among children continues to climb. It is likely that two COVID-19 vaccines will be available in the U.S. by year-end and could be widely available by the spring of 2021. For children, that timeline will be longer.
In the meantime, experts say it is important for schools, child care centers and parents to remain vigilant.
“In a way, COVID is a little like Russian roulette,” McAlister said. “There’s this element where we still can’t predict who is going to be relatively fine and shrug the virus off, and who’s not.”
Experts are still learning about COVID-19. The information in this story is what was known or available as of publication, but guidance can change as scientists discover more about the virus. Please check the Centers for Disease Control and Prevention for the most updated recommendations.
This article originally appeared on HuffPost and has been updated.