A
large new study from South Korea offers an answer: Children younger than 10 transmit to others much less often than adults do, but the risk is not zero. And those between the ages of 10 and 19 can spread the virus at least as well as adults do.
The findings suggest that as schools reopen, communities will see clusters of infection take root that include children of all ages, several experts cautioned.
...
Several studies from Europe and Asia have suggested that young children are less likely to get infected and to spread the virus. But most of those studies were small and flawed, said Dr. Ashish Jha, director of the Harvard Global Health Institute.
The new study “is very carefully done, it’s systematic and looks at a very large population,” Dr. Jha said. “It’s one of the best studies we’ve had to date on this issue.”
Other experts also praised the scale and rigor of the analysis. South Korean researchers identified 5,706 people who were the first to report Covid-19 symptoms in their households between Jan. 20 and March 27, when schools were closed, and then traced the 59,073 contacts of these “index cases.” They tested all of the household contacts of each patient, regardless of symptoms, but only tested symptomatic contacts outside the household.
...
The study is more worrisome for children in middle and high school.
This group was even more likely to infect others than adults were, the study found. But some experts said that finding may be a fluke or may stem from the children’s behaviors.