(HealthDay News — SARS-CoV-2 antigen testing (BinaxNOW) could be a useful tool for identifying contagious people early in the course of a nursing home outbreak, according to a study published online April 27 in the Annals of Internal Medicine.
Susannah L. McKay, PhD, MPH, from the US Centers for Disease Control and Prevention in Atlanta, and colleagues conducted 3 facility-wide rounds of testing during a nursing home outbreak where paired respiratory specimens were collected to assess performance of the BinaxNOW antigen test compared to virus culture and real-time reverse transcription-polymerase chain reaction (RT-PCR); 532 paired specimens were obtained from 234 available residents and staff.
The researchers found that the percentage of positive agreement (PPA) was 95% for BinaxNOW with virus culture used for detection of replication-competent virus. The overall PPA of antigen testing was 69% with RT-PCR, and the percentage of negative agreement was 98%. When only the first positive test was analyzed for each participant, the PPA of antigen testing with RT-PCR was 82% and 52% among symptomatic and asymptomatic people, respectively. BinaxNOW performed well in early infection compared with RT-PCR and virus culture (86% and 95%, respectively), but poorly in late infection (51% and no recovered virus, respectively).
“These findings show that the BinaxNOW antigen test performed well for identifying people who are infectious and will likely perform well when used serially as a screening tool for nascent and emerging COVID-19 outbreaks,” the authors write.