One-third of SARS-CoV-2 Infections May Be Asymptomatic
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Roughly one-third of people infected with SARS-CoV-2 have no symptoms, according to a review of data from more than 350 studies published through April 2021. Asymptomatic infections were more common in children than in the elderly or in people without preexisting medical conditions, said Pratha Sah of Yale School of Public Health, who led the analysis published in PNAS.

Her team estimates that 46.7% of infected children have no symptoms, she said. "This is especially concerning because settings with close, extensive contact among large groups of younger individuals are particularly susceptible to superspreader events of COVID-19, which may go undetected" if school authorities only watch for symptoms, she told Reuters.

Senior author Alison Galvani, also of the Yale School of Public Health, noted that asymptomatic individuals can still pass the virus to others, which makes mask-wearing important as schools reopen.