SARS-CoV-2 Seroprevalence among a Southern U.S. Population Indicates Limited Asymptomatic Spread under Physical Distancing Measures
Amir Barzin,
John L. Schmitz,
Samuel Rosin,
Rameet Sirpal,
Martha Almond,
Carole Robinette,
Samantha Wells,
Michael Hudgens,
Andrew Olshan,
Stephanie Deen,
Patrick Krejci,
Eugenia Quackenbush,
Kevin Chronowski,
Caleb Cornaby,
Janette Goins,
Linda Butler,
Julia Aucoin,
Kim Boyer,
Janet Faulk,
Devena Alston-Johnson,
Cristen Page,
Yijun Zhou,
Lynne Fiscus,
Blossom Damania,
Dirk P. Dittmer,
David B. Peden
Affiliations
Amir Barzin
The University of North Carolina at Chapel Hill School of Medicine, Department of Family Medicine, Chapel Hill, North Carolina, USA
John L. Schmitz
The University of North Carolina at Chapel Hill School of Medicine, Department of Pathology and Laboratory Medicine and UNC Hospitals McLendon Clinical Laboratories, Chapel Hill, North Carolina, USA
Samuel Rosin
The University of North Carolina at Chapel Hill Gillings School of Global Public Health, Department of Biostatistics, Chapel Hill, North Carolina, USA
Rameet Sirpal
UNC Physicians Network, Chapel Hill, North Carolina, USA
Martha Almond
The University of North Carolina at Chapel Hill School of Medicine, Center for Environmental Medicine, Asthma and Lung Biology, Chapel Hill, North Carolina, USA
Carole Robinette
The University of North Carolina at Chapel Hill School of Medicine, Center for Environmental Medicine, Asthma and Lung Biology, Chapel Hill, North Carolina, USA
Samantha Wells
The University of North Carolina at Chapel Hill School of Medicine, Department of Family Medicine, Chapel Hill, North Carolina, USA
Michael Hudgens
The University of North Carolina at Chapel Hill Gillings School of Global Public Health, Department of Biostatistics, Chapel Hill, North Carolina, USA
Andrew Olshan
The University of North Carolina at Chapel Hill Gillings School of Global Public Health, Department of Epidemiology, Chapel Hill, North Carolina, USA
Stephanie Deen
UNC Health Information Services Division, Chapel Hill, North Carolina, USA
Patrick Krejci
UNC Physicians Network, Chapel Hill, North Carolina, USA
Eugenia Quackenbush
The University of North Carolina at Chapel Hill School of Medicine, Department of Emergency Medicine, Chapel Hill, North Carolina, USA
Kevin Chronowski
The University of North Carolina at Chapel Hill School of Medicine, Department of Emergency Medicine, Chapel Hill, North Carolina, USA
Caleb Cornaby
The University of North Carolina at Chapel Hill School of Medicine, Department of Pathology and Laboratory Medicine and UNC Hospitals McLendon Clinical Laboratories, Chapel Hill, North Carolina, USA
Janette Goins
The University of North Carolina at Chapel Hill, North Carolina Translational and Clinical Sciences Institute, Chapel Hill, North Carolina, USA
Linda Butler
UNC REX Healthcare, Raleigh, North Carolina, USA
Julia Aucoin
UNC REX Healthcare, Raleigh, North Carolina, USA
Kim Boyer
UNC REX Healthcare, Raleigh, North Carolina, USA
Janet Faulk
UNC REX Healthcare, Raleigh, North Carolina, USA
Devena Alston-Johnson
UNC Health Nash General Hospital, Rocky Mount, North Carolina, USA
Cristen Page
The University of North Carolina at Chapel Hill School of Medicine, Department of Family Medicine, Chapel Hill, North Carolina, USA
Yijun Zhou
The University of North Carolina at Chapel Hill School of Medicine, Department of Microbiology and Immunology, Chapel Hill, North Carolina, USA
Lynne Fiscus
UNC Physicians Network, Chapel Hill, North Carolina, USA
Blossom Damania
The University of North Carolina at Chapel Hill School of Medicine, Department of Microbiology and Immunology, Chapel Hill, North Carolina, USA
Dirk P. Dittmer
The University of North Carolina at Chapel Hill School of Medicine, Department of Microbiology and Immunology, Chapel Hill, North Carolina, USA
David B. Peden
The University of North Carolina at Chapel Hill School of Medicine, Center for Environmental Medicine, Asthma and Lung Biology, Chapel Hill, North Carolina, USA
ABSTRACT Characterizing the asymptomatic spread of SARS-CoV-2 is important for understanding the COVID-19 pandemic. This study was aimed at determining asymptomatic spread of SARS-CoV-2 in a suburban, Southern U.S. population during a period of state restrictions and physical distancing mandates. This is one of the first published seroprevalence studies from North Carolina and included multicenter, primary care, and emergency care facilities serving a low-density, suburban and rural population since description of the North Carolina state index case introducing the SARS-CoV-2 respiratory pathogen to this population. To estimate point seroprevalence of SARS-CoV-2 among asymptomatic individuals over time, two cohort studies were examined. The first cohort study, named ScreenNC, was comprised of outpatient clinics, and the second cohort study, named ScreenNC2, was comprised of inpatients unrelated to COVID-19. Asymptomatic infection by SARS-CoV-2 (with no clinical symptoms) was examined using an Emergency Use Authorization (EUA)-approved antibody test (Abbott) for the presence of SARS-CoV-2 IgG. This assay as performed under CLIA had a reported specificity/sensitivity of 100%/99.6%. ScreenNC identified 24 out of 2,973 (0.8%) positive individuals among asymptomatic participants accessing health care during 28 April to 19 June 2020, which was increasing over time. A separate cohort, ScreenNC2, sampled from 3 March to 4 June 2020, identified 10 out of 1,449 (0.7%) positive participants. IMPORTANCE This study suggests limited but accelerating asymptomatic spread of SARS-CoV-2. Asymptomatic infections, like symptomatic infections, disproportionately affected vulnerable communities in this population, and seroprevalence was higher in African American participants than in White participants. The low, overall prevalence may reflect the success of shelter-in-place mandates at the time this study was performed and of maintaining effective physical distancing practices among suburban populations. Under these public health measures and aggressive case finding, outbreak clusters did not spread into the general population.
