Study Compares Rapid Antigen Test Detection of Omicron, Delta SARS-CoV-2 Variants

Rapid antigen tests could detect the Omicron variant of SARS-CoV-2 just as well as the Delta variant, according to a new study appearing in the Annals of Internal Medicine. The analysis by University of Massachusetts Chan Medical School researchers relied on data from the prospective cohort study Test Us At Home in which participants serially took both at-home antigen and send-in PCR COVID-19 tests over a period of 10 to 15 days. This analysis focuses on the 5,779 individuals who tested negative for SARS-CoV-2 at the start of the parent study and the 207 individuals of those who later tested positive for the virus by PCR. Rapid antigen tests had similar sensitivities for detecting the Omicron and Delta SARS-CoV-2 variants, though did not always catch  positive cases when they were detected by PCR. "Taken together, our findings suggest that Ag-RDTs detect infections similarly for the Delta and Omicron variants, with overall low detection rates on the same day as an initial RT-PCR–positive result and higher detection rates when a second test is used 48 hours after the first," the researchers add.