Surveillance of SARS-CoV-2 in Asymptomatic Faculty and Staff at the University of Wisconsin-Madison

Abstract

Introduction: Surveillance of SARS-CoV-2 among university employees is an important part of mitigation strategies to prevent asymptomatic transmission and ensure a safe learning and work environment. Here, we assess the feasibility and performance of a program that relies on monitored self-collected nasal swabs to detect SARS-CoV-2 among asymptomatic faculty and staff.

Methods: We recruited 1,030 faculty and staff via rolling enrollment who completed the required University of Wisconsin-Madison employee COVID-19 training and reported working on campus. Asymptomatic participants visited a designated location during a specified timeframe each week where they self-collected nasal swabs supervised by study staff. Specimens were stored in a cooler between 2 °C and 8 °C, then transported to the Wisconsin Veterinary Diagnostic Laboratory for polymerase chain reaction testing. Symptomatic participants or participants with a known exposure were advised to test elsewhere and follow quarantine guidelines from the Centers for Disease Control and Prevention.

Results: Over the course of 31 weeks, 1,030 participants self-collected 17,323 monitored nasal swabs resulting in high participation (90%). SARS-CoV-2 was detected in 16 specimens. Eight specimens were inconclusive but were treated as positive results because of the implied detection of 1 or more SARS-CoV-2 genes. There were no invalid tests. Weekly SARS-CoV-2 incidence among participants ranged from 0 to 1.54% (x̄ = 0.20%). The SARS-CoV-2 incidence among participants was similar to estimated incidence in the greater university employee population.

Conclusion: Weekly SARS-CoV-2 surveillance of asymptomatic faculty and staff on campus allowed for estimation of weekly SARS-CoV-2 incidence among on-campus employees. This surveillance protocol presents a low-cost, effective, and scalable option to identify asymptomatic cases of SARS-CoV-2 among university employees.