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Researchers at the UNC School of Medicine collaborated with UNC Health and found that 0.8 percent of patients who came to a UNC Health facility for non-COVID-19 related reasons during the NC stay-at-home mandate tested positive for the novel coronavirus.

In the first published COVID-19 asymptomatic surveillance study in North Carolina , UNC School of Medicine researchers enrolled nearly 3,000 patients between April 28 and June 19 in a study called ScreenNC to determine the rate of asymptomatic positive carriers of SARS-CoV-2, the virus that causes COVID-19.

The researchers, who published their findings in mBio, a journal of the American Society for Microbiology, collaborated with UNC Health system facilities in suburban areas of North Carolina to enroll 2,973 participants who came to UNC clinics for non-coronavirus reasons. Once enrolled in the ScreenNC, study participants from 267 zip codes were tested for COVID-19.

The researchers, led by study co-senior authors David Peden, MD, Dirk Dittmer, PhD and Blossom Damania, PhD, found that 24 patients tested positive, a rate of 0.8 percent of all study participants. In a separate cohort, called ScreenNC2, 10 of 1,449 asymptomatic UNC Health patients (0.7 percent) tested positive between March 3 and June 4, 2020. Black participants had twice the unadjusted positivity rate than whites (1.5 percent). The analysis of other demographic factors was not possible due to the small number of positive cases.

“This was a unique and impressive collaboration between many departments and dedicated people at the UNC School of Medicine and across the UNC Health system and UNC Physician Network clinics,” said Damania, vice dean of research at the UNC School of Medicine and Boshamer Distinguished Professor of Microbiology and Immunology. “Everyone worked together seamlessly and in a collaborative fashion to make this happen. We are also grateful to the efforts of the three lead co-authors on this project, Amir Barzin, MD, assistant professor in the Department of Family Medicine, John Schmitz, PhD, professor in the UNC Department of Pathology and Laboratory Medicine, and Samuel Rosin, a graduate student in the UNC Department of Biostatistics at the UNC Gillings School of Global Public Health.”

“Our study identified very limited prevalence of SARS-CoV-2 among asymptomatic individuals accessing the UNC Health system during the NC stay-at-home mandate earlier this year,” said Dittmer, professor in the UNC Department of Microbiology and Immunology and Virology Program Leader and the UNC Lineberger Comprehensive Cancer Center.

“Yet, because COVID-19 is so transmissible from person to person, we demonstrated the importance of maintaining consistent protocols, such as mask usage and physical distancing, as much as possible,” added Peden, the Andrews Distinguished Professor of Pediatrics and Deputy Director, Center for Environmental Medicine, Asthma and Lung Biology.

Determining the extent of asymptomatic COVID-19 transmission can help shape models of disease spread and can inform public health decisions, but it isn’t easy to conduct large-scale random surveillance studies during a public health emergency when stay-at-home orders are in place and healthcare and testing supplies are in high demand. Most of the early modeling and asymptomatic studies of COVID-19 were conducted in densely populated urban hot spots, such as Wuhan, New York City, Los Angeles and Seattle, with several means to rapidly spread the disease. By contrast, North Carolina is largely rural and suburban, with limited public transportation. For these reasons, UNC School of Medicine researchers quickly teamed up with UNC Health leaders to enroll North Carolinians who were seeking healthcare for reasons having nothing to do with COVID-19.

ScreenNC researchers were able to enroll nearly 4,500 participants to determine that it was unlikely herd immunity would have been reached quickly in the early part of the pandemic and even throughout 2020 without risking many more deaths and overwhelming healthcare systems. This research suggests that shelter-in-place policies and physical distancing measures were important tools to suppress COVID-19 transmission and limit infection of the majority of the population in North Carolina.

This research was funded by the UNC School of Medicine, UNC Health, and the University Cancer Research Fund. It was completed in collaboration between the UNC Department of Family Medicine, UNC McClendon Labs, UNC Department of Pathology and Laboratory Medicine, UNC Gillings School of Global Public Health, UNC Center for Environmental Medicine, Asthma, and Lung Biology, UNC Department of Epidemiology, UNC Department of Emergency Medicine, UNC Rex Healthcare, UNC Physicians Network, UNC Health Nash General Hospital, UNC Translational and Clinical Sciences Institute, UNC Department of Microbiology and Immunology, UNC Lineberger Comprehensive Cancer Center, and UNC Department of Pediatrics.

Along with Damania, Dittmer, and Peden, authors of the study are Amir Barzin, John L. Schmitz, Samuel Rosin, Rameet Sirpal, Martha Almond, Carole, Robinette, Samatha 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, and Lynne Fiscus.

Media contact: Mark Derewicz, 919-923-0959