Performance Evaluation of Serial SARS-CoV-2 Rapid Antigen Testing During a Nursing Home Outbreak

• Published in: Annals of Internal Medicine 2021-07
• Main Authors: McKay, Susannah L, Tobolowsky, Farrell A, Moritz, Erin D, Hatfield, Kelly M, Bhatnagar, Amelia, LaVoie, Stephen P, Jackson, David A, Lecy, K Danielle, Bryant-Genevier, Jonathan, Campbell, Davina, Freeman, Brandi, Gilbert, Sarah E, Folster, Jennifer M, Medrzycki, Magdalena, Shewmaker, Patricia L, Bankamp, Bettina, Radford, Kay W, Anderson, Raydel, Bowen, Michael D, Negley, Jeanne, Reddy, Sujan C, Jernigan, John A, Brown, Allison C, McDonald, L Clifford, Kutty, Preeta K, CDC Infection Prevention, Team, Control, the CDC COVID-19 Surge Laboratory Group
• Format: Article
• Language: English
• DOI: 10.7326/M21-0422

Visual Abstract. Serial SARS-CoV-2 Rapid Antigen Testing During a Nursing Home Outbreak. Many have hoped that rapid SARS-CoV-2 antigen testing could reduce the tragic toll of COVID-19 in nursing homes. This study evaluated the performance of the BinaxNOW antigen test in a nursing home during an ongoing SARS-CoV-2 outbreak. * Download figure * Download PowerPoint Abstract Background: To address high COVID-19 burden in U.S. nursing homes, rapid SARS-CoV-2 antigen tests have been widely distributed in those facilities. However, performance data are lacking, especially in asymptomatic people. Objective: To evaluate the performance of SARS-CoV-2 antigen testing when used for facility-wide testing during a nursing home outbreak. Design: A prospective evaluation involving 3 facility-wide rounds of testing where paired respiratory specimens were collected to evaluate the performance of the BinaxNOW antigen test compared with virus culture and real-time reverse transcription polymerase chain reaction (RT-PCR). Early and late infection were defined using changes in RT-PCR cycle threshold values and prior test results. Setting: A nursing home with an ongoing SARS-CoV-2 outbreak. Participants: 532 paired specimens collected from 234 available residents and staff. Measurements: Percentage of positive agreement (PPA) and percentage of negative agreement (PNA) for BinaxNOW compared with RT-PCR and virus culture. Results: BinaxNOW PPA with virus culture, used for detection of replication-competent virus, was 95%. However, the overall PPA of antigen testing with RT-PCR was 69%, and PNA was 98%. When only the first positive test result was analyzed for each participant, PPA of antigen testing with RT-PCR was 82% among 45 symptomatic people and 52% among 343 asymptomatic people. Compared with RT-PCR and virus culture, the BinaxNOW test performed well in early infection (86% and 95%, respectively) and poorly in late infection (51% and no recovered virus, respectively). Limitation: Accurate symptom ascertainment was challenging in nursing home residents; test performance may not be representative of testing done by nonlaboratory staff. Conclusion: Despite lower positive agreement compared with RT-PCR, antigen test positivity had higher agreement with shedding of replication-competent virus. These results suggest that antigen testing could be a useful tool to rapidly identify contagious people at risk for transmitting SARS-CoV-2 during nascent outbreaks and help reduce COVID-19