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Since emergence of COVID-19 at the end of last year, it has appeared that children are infected at a lower rate and play a less significant role in transmission of the virus (NEJM Pediatr Adolesc Med 2020 Jul 19; [e-pub] and Pediatrics 2020; 146:e20201576). In the current study, researchers analyzed age-specific COVID-19 rates in close to 60,000 contacts, including 10,600 household contacts, of almost 6000 patients with confirmed COVID-19 in South Korea during a 2-month period. Contacts were tested for SARS-CoV-2 if they were in a high-risk group or were symptomatic; other contacts self-quarantined and were observed for symptoms for 14 days. Findings include the following:
Twelve percent of household contacts developed COVID-19.
Two percent of nonhousehold contacts developed COVID-19.
Nineteen percent of household contacts of the 124 10-to-19-year-old COVID-19 index cases developed COVID-19 compared with only 5% who were in household contact with 1 of the 29 index cases who were aged ≤9 years.
The detection rate among nonhousehold contacts was lower than among household contacts in all age groups.
Park YJ et al. Contact tracing during coronavirus disease outbreak, South Korea, 2020. Emerg Infect Dis 2020 Jul 16; 26: [e-pub]. (https://doi.org/10.3201/eid2610.201315)
Comment
This robust contact-tracing study demonstrates the efficiency with which SARS-CoV-2 spreads within households, but also highlights the potential role that older school-age children play in virus transmission. Younger children, although representing a small percentage of index cases, transmitted at a lower rate compared with older children. We need more data to paint a clearer picture of the transmission risk that children pose, both to adults and to each other. This information will help determine how best to proceed with school openings, but from these preliminary data, it seems imperative to consider children's ages in planning school reopenings, perhaps bringing the youngest children back into the classroom first.