Just 2% of SARS-CoV-2−positive individuals carry 90% of virus in circulation

  

View ORCID ProfileQing Yang, Tassa K. Saldi, Patrick K. Gonzales, Erika Lasda,  View ORCID ProfileCarolyn J. Decker, Kimngan L. Tat,  View ORCID ProfileMorgan R. Fink, Cole R. Hager,  View ORCID ProfileJack C. Davis, Christopher D. Ozeroff, Denise Muhlrad, Stephen K. Clark, Will T. Fattor, Nicholas R. Meyerson,  View ORCID ProfileCamille L. Paige, Alison R. Gilchrist,  View ORCID ProfileArturo Barbachano-Guerrero, Emma R. Worden-Sapper, Sharon S. Wu, Gloria R. Brisson, Matthew B. McQueen, Robin D. Dowell,  View ORCID ProfileLeslie Leinwand,  View ORCID ProfileRoy Parker, and  View ORCID ProfileSara L. Sawyer

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PNAS May 25, 2021 118 (21) e2104547118; https://doi.org/10.1073/pnas.2104547118

PDF: https://www.pnas.org/content/pnas/118/21/e2104547118.full.pdf

Significance

We analyzed data from saliva-based COVID-19 screening deployed on the University of Colorado Boulder campus. Our dataset is unique in that all SARS-CoV-2−positive individuals reported no symptoms at the time of saliva collection, and therefore were infected but asymptomatic or presymptomatic. We found that 1) the distribution of viral loads observed in our asymptomatic college population was indistinguishable from what has been reported in hospitalized populations; 2) regardless of symptomatic status, approximately 50% of individuals who test positive for SARS-CoV-2 seem to be in noninfectious phases of the infection; and 3) just 2% of infected individuals carry 90% of the virions circulating within communities, serving as viral “supercarriers” and likely also superspreaders.

Abstract

We analyze data from the fall 2020 pandemic response efforts at the University of Colorado Boulder, where more than 72,500 saliva samples were tested for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) using qRT-PCR. All samples were collected from individuals who reported no symptoms associated with COVID-19 on the day of collection. From these, 1,405 positive cases were identified. The distribution of viral loads within these asymptomatic individuals was indistinguishable from what has been previously observed in symptomatic individuals. Regardless of symptomatic status, ∼50% of individuals who test positive for SARS-CoV-2 seem to be in noninfectious phases of the disease, based on having low viral loads in a range from which live virus has rarely been isolated. We find that, at any given time, just 2% of individuals carry 90% of the virions circulating within communities, serving as viral “supercarriers” and possibly also superspreaders.

https://www.pnas.org/content/118/21/e2104547118