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 timeViral dynamics may differ in superspreadersSome participants shed live SARS-CoV-2 for only a day or two, while others did so for up to 9 days. "Based on that finding, we predict that those people who are shedding virus for more than a week are going to be a much greater risk of transmission than someone who only has live virus detectable for a day or two," senior author Christopher Brooke, PhD, of the