SARS-CoV-2 infections frequently asymptomatic in children

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections are often asymptomatic among children, especially those aged 0 to 4 years, according to a study published online Aug. 31 in JAMA Network Open.

Ruth A. Karron, M.D., from the Johns Hopkins University Bloomberg School of Public Health in Baltimore, and colleagues conducted a prospective cohort study enrolling 690 participants from 175 Maryland households with one or more children aged 0 to 4 years from Nov. 24, 2020, and Oct. 15, 2021. Participants completed weekly symptom questionnaires and submitted self-collected nasal swabs for SARS-CoV-2 testing.

Of the participants, 256, 100, and 334 were children aged 0 to 4 years, children aged 5 to 17 years, and adults aged 18 to 74 years, respectively. The researchers found that during the surveillance period, 7.8 percent of participants had SARS-CoV-2 infection, including 8.6, 11.0, and 6.3 percent of children aged 0 to 4 years, children aged 5 to 17 years, and adults, respectively. The corresponding incidence rates per 1,000 person-weeks were 2.25, 3.48, and 1.08. Compared with adults, children aged 0 to 17 years were more frequently asymptomatic (36.7 versus 14.3 percent), with children aged 0 to 4 years the most frequently asymptomatic (36.8 percent). There was no difference in the highest detected viral load between asymptomatic and symptomatic individuals overall or by age group. For adults, but not children, the number of symptoms was significantly correlated with viral load.

"Although the implications of these findings for household transmission remain to be evaluated, they suggest that SARS-CoV-2 infection may be underrecognized and that symptoms may not reflect infectiousness in young children," the authors write.

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