A study today in Clinical Infectious Diseases conducted across 12 tertiary care pediatric hospitals in Canada and the United States shows that asymptomatic children with COVID-19, especially preschoolers, contribute significantly to household transmission.

The researchers discovered that 10.6% of exposed household contacts developed symptomatic illness within 14 days of exposure to asymptomatic test-positive children, a rate higher than expected.

“We determined that the risk of developing symptomatic illness within 14 days was 5 times greater among household contacts of asymptomatic SARS-CoV-2–positive children,” the authors wrote.

They also found that 6 of 77 asymptomatic SARS-CoV-2–infected children during a 3-month follow-up developed long COVID, or 7.8% of them.