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Researchers in South Korea have found that children between the ages of 10 and 19 can transmit Covid-19 within a household just as much as adults, according to new research published in the US Centers for Disease Control and Prevention journal Emerging Infectious Diseases.

Researchers also found that children ages 9 and younger transmitted the virus within their household at rates that were a lot lower.

Researchers from the Korea Centers for Disease Control and Prevention looked at reports of 59,073 contacts of 5,706 coronavirus patients.

Overall, the researchers detected Covid-19 in 11.8% of 10,592 household contacts. For 48,481 non-household contacts, 1.9% tested positive for Covid-19.

When the initial patient in a household was younger than 10, the researchers found that 5.3% of household contacts tested positive for Covid-19. When the initial patient was between the ages of 10 and 19, 18.6% of contacts tested positive.

Rates were higher for contacts of children than adults,” the authors said. “These risks largely reflected transmission in the middle of mitigations and therefore might characterize transmission dynamics during school closure.”

Researchers also found that the highest Covid-19 rate for household contacts of school-age children and the lowest rates for children younger than 9 was the middle of school closures.

“Although the detection rate for contacts of preschool-aged children was lower, young children may show higher attack rates when the school closure ends, contributing to community transmission of Covid-19,” the study said.

This is one study in many,” said Dr. Ashish Jha, director of the Harvard Global Health Institute, speaking on CNN’s “Inside Politics” on Sunday. “And the general consensus that I think most of us has had is that younger kids definitely spread a lot less. Older kids, especially as you start getting into teenagers and older teenagers, start looking like adults.”

Jha said that, ultimately, what you want to do is get the virus suppressed in the community so schools can reopen safely.

“You might have a different threshold for getting kids kindergarten through 5, let’s say, back in at an earlier level,” Jha said. “And you may need to wait a little bit longer until the virus levels really are down before you open up high schools.”

There are some limitations to the study, the authors said, including that the number of cases may have been underestimated and that they were unable to assess the true difference in transmissibility between household and non-household contacts because of the different testing thresholds.