Daily infectious SARS-CoV-2 virus shedding varied substantially among 60 newly diagnosed asymptomatic or mildly ill COVID-19 patients early in the pandemic, suggesting that individual differences in viral dynamics may account for "superspreading," according to a first-of-its-kind modeling study published yesterday in Nature Microbiology.

A superspreader transmits the virus to an exceptionally large number of other people. "Transmission of SARS-CoV-2 by both presymptomatic and asymptomatic individuals has been a major contributor to the explosive spread of this virus," the researchers wrote.

Led by scientists from the Los Alamos National Laboratory and the University of Illinois, the study tracked daily SARS-CoV-2 viral loads in university staff and students' saliva and nose starting within 24 hours of diagnosis for up to 14 days early in the pandemic.

The team used rapid antigen COVID-19 tests, polymerase chain reaction (PCR) tests, and viral culture to determine loads of live (infectious) SARS-CoV-2 and noninfectious viral RNA. The researchers used mathematical models to estimate viral replication and clearance rates and overall infectiousness for each participant. Participants had a median age of 28 years and were primarily White; none had been vaccinated against COVID-19, because vaccines weren't available at that time

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