FRIDAY, Sept. 25, 2020 (HealthDay News) — About one-fifth of individuals with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection are asymptomatic and their viral load is comparable to that of patients with mild symptoms, according to a study published online Sept. 22 in Thorax.

Sang Hyun Ra, from the Asan Medical Center in Seoul, South Korea, and colleagues recruited study participants from a community facility designed for isolation of patients with mild COVID-19 to examine viral load in asymptomatic individuals with SARS-CoV-2 infection and symptomatic patients. Viral loads were measured in the upper respiratory tract with real-time reverse transcription-polymerase chain reaction (RT-PCR).

The researchers found that 41 (19 percent) of the 213 patients with SARS-CoV-2 infection had remained asymptomatic from potential exposure to laboratory confirmation and admission; after a median of 13 days, 95 percent of these patients underwent follow-up RT-PCR testing. Eighty-four percent of the 172 symptomatic patients underwent follow-up RT-PCR testing. At follow-up, 54 and 64 percent of asymptomatic and symptomatic individuals, respectively, tested positive for SARS-CoV-2. There were no significant differences noted in mean cycle threshold values of the E, RdRp, and N genes for asymptomatic and symptomatic individuals.

“Asymptomatic individuals with SARS-CoV-2 infection may contribute to the ongoing community spread of COVID-19, but further studies with cell culture are needed to evaluate the transmissibility of COVID-19 from asymptomatic individuals to inform a recommendation on universal personal protective equipment,” the authors write.

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