January 4, 2021

Performance of an Antigen-Based Test for Asymptomatic and Symptomatic SARS-CoV-2 Testing at Two University Campuses — Wisconsin, September–October 2020

Category: Article Summary

Topic: Testing and Treatment

Keywords (Tags): colleges, testing

Use of SARS-CoV-2 antigen testing on two university campuses had a positive predictive value of 33% and a negative predictive value of 99%. Compared to RT-PCR testing, the Sofia antigen test had a sensitivity of 80.0% and specificity of 98.9% among symptomatic people. Accuracy was lower (sensitivity 41.2% and specificity 98.4%) when used for screening of asymptomatic people. Paired nasal swabs were collected from students, faculty, staff members, and other affiliates at two Wisconsin university campuses. Among those with false-negative antigen tests, two symptomatic individuals with a negative antigen test had virus detected by culture, indicating potential infectiousness among symptomatic individuals with a false-negative antigen test. However, none of the asymptomatic false positive individuals had virus detected by culture. The authors suggest that asymptomatic people with negative antigen results are unlikely to be infected with SARS-CoV-2.

Pray et al. (Jan 1, 2021). Performance of an Antigen-Based Test for Asymptomatic and Symptomatic SARS-CoV-2 Testing at Two University Campuses — Wisconsin, September–October 2020. MMWR. https://doi.org/10.15585/mmwr.mm695152a3