July 21, 2020 -- Children and teens between ages 10-19 are more likely to spread the coronavirus among family members than adults and children under 10, according to a new study in South Korea. The results were published online as an early release article from the journal Emerging Infectious Diseases and could be updated before the official release in October.
Researchers at the CDC and Korea Centers for Disease Control and Prevention analyzed reports from nearly 60,000 people who had contact with 5,706 coronavirus patients between January and March. They found that 12% of household contacts had COVID-19, and about 2% of non-household contacts contracted the virus.
“Use of personal protective measures and social distancing reduces the likelihood of transmission,” the authors wrote.
In households with coronavirus patients between ages 10-19, nearly 19% of contacts tested positive for COVID-19. This was the highest rate of transmission among the age groups. Children under age 10 had the lowest rate at 5.3%.
Based on the timing of South Korea’s lockdown measures, the high percentage among teens and tweens but not among younger children could explain how transmission occurred around school closures, the authors wrote. In China, for instance, a contact-tracing study showed that school closures and social distancing significantly reduced the rate of COVID-19 among school-aged children. Additional studies, including antibody tests, would better explain the public health benefit of school closures to prevent the spread of the virus, they added.
“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,” they wrote.
Higher detection among household contacts rather than non-household contacts could also reflect how the virus moved among family members when they were at home during shelter-in-place orders.
“Given the high infection rate within families, personal protective measures should be used at home to reduce the risk for transmission,” they wrote.
If someone at home has tested positive for the coronavirus, social distancing and personal hygiene are the “most viable options” to prevent spread of the virus, the authors said. Future research might be able to explain whether wearing face masks at home could help, especially if some family members have underlying conditions or face a high risk of contracting COVID-19.