What New Data Reveals About Kids and Coronavirus Spread

New research shows kids can spread Covid-19 to family members, even when they are asymptomatic

Photo by Deleece Cook on Unsplash

All around the world, kids are going back to school. While some children have the option to learn from home, many are returning to physical classrooms. The decision to send kids back to in-person school is fraught: While doing so can be good for their mental health and development and it can provide child care for caregivers who need to work, the spread of Covid-19 among children — and their ability to pass it to other family members — is still not well understood.

As my colleague Dana Smith previously wrote in Elemental, kids don’t seem to be as vulnerable to Covid-19 as adults, and scientists still aren’t sure why. But the idea that children are immune to Covid-19, which gained prominence in the early days of the pandemic, has been refuted by newer data. Kids can spread the virus; it’s just not clear how often they do so.

The official stance of the World Health Organization is that kids (up to 18 years old) tend to have milder illness and fewer symptoms and that their role in transmission still isn’t understood. Cases among kids may go unnoticed because they are often asymptomatic. In a press conference at the end of August, Hans Kluge, MD, the WHO regional director for Europe, said that kids aren’t thought to be a main contributor to transmission, but there are “more and more publications that adds to the body of evidence that children do play a role in the transmission but that this is, so far, more linked with social gatherings.”

Research published this week sheds light on whether kids can transmit Covid-19 and whether they do so when asymptomatic. On Monday, a report published by the Centers for Disease Control and Prevention showed that young children (under 10 years of age) who were asymptomatic could get infected with Covid-19 at childcare centers and spread it to family members even when asymptomatic. Investigating three outbreaks at three childcare centers in Salt Lake City, Utah, the researchers identified 12 kids who got Covid-19 in those settings and found that those kids had infected 12 adults who didn’t work at the facilities, including family members. Two out of three asymptomatic kids in the sample were able to transmit the virus.

“They are transmitting it to people when they’re asymptomatic,” said co-author Mary Hill, PhD, an epidemiologist with the Salt Lake County health department, in an interview with Aspen Public Radio. If kids are exposed to a person with Covid-19 at a childcare center, she said, they should be tested even if they’re asymptomatic. And because the outbreaks in at least two of the three childcare centers originated with one of the childcare workers, Hill argues that workers should be given better paid leave so they are more comfortable staying home if they are sick.

A research letter authored by researchers in Milan, Italy and published in JAMA on Monday shed some light on how often kids with Covid-19 are asymptomatic relative to adults. The hope is that this information will help build a better understanding of how big a role kids play in the spread of the virus. The study investigated kids and adults who were admitted to a Milan hospital for reasons unrelated to Covid-19; all of these people were asymptomatic for Covid-19, but the hospital had a policy of testing everyone. Between March 1 and April 30, 83 kids and 131 adults who met the research criteria showed up at the hospital. Of the 83 kids, only one tested positive for Covid-19 (1.3% of all kids), whereas 12 in 131 adults tested positive (9.2% of all adults).

This data, the researchers write, “do not support the hypothesis that children are at higher risk of carrying SARS-CoV-2 asymptomatically than adults.”

These two new pieces of research don’t offer any conclusions, but they support some existing ideas about kids and the transmission of Covid-19, which can be helpful for parents weighing the risks of sending kids to school versus keeping them at home. For one, it’s increasingly becoming clear that kids who attend school or daycare can acquire Covid-19 there and spread it to people at home. It’s also becoming clear that kids are often asymptomatic but can still spread the virus, which underscores the importance of testing kids who come into contact with a person with Covid-19. However, whether kids are more often asymptomatic carriers than adults is not well understood.

It’s understandable if parents are anxious about sending their kids to school while so much remains unknown, especially as some states, in particular Florida, have seen an uptick in positive cases among children. There’s some comfort to be taken in the interventions that are proven to prevent Covid-19’s spread among kids: Hand-washing remains as critical as ever — the CDC recommends turning it into a family activity — and Mill, the Salt Lake City epidemiologist, recommends masks for kids two years and older.

Editor, Medium Coronavirus Blog. Senior editor at Future Human by OneZero. Previously: science at Inverse, genetics at NYU.

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