HealthDay News — Severe acute respiratory syndrome coronavirus 2 (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, Ph.D., M.P.H., from the U.S. Centers for Disease Control and Prevention in Atlanta, and colleagues conducted three 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 percent for BinaxNOW with virus culture used for detection of replication-competent virus. The overall PPA of antigen testing was 69 percent with RT-PCR, and the percentage of negative agreement was 98 percent. When only the first positive test was analyzed for each participant, the PPA of antigen testing with RT-PCR was 82 and 52 percent among symptomatic and asymptomatic people, respectively. BinaxNOW performed well in early infection compared with RT-PCR and virus culture (86 and 95 percent, respectively), but poorly in late infection (51 percent 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.