COVID-19 Testing: Impact of Omicron variants on diagnostic reliability

Rapid antigen testing continues to be recommended across the world for the prevention of transmission of SARS-CoV-2 for anyone with COVID-19 symptoms, recent exposure, those visiting high-risk individuals or those recently in crowded spaces while traveling without wearing a mask. Evidence of decreasing diagnostic reliability of individual tests and potential benefits and harms of non-targeted testing is increasingly becoming a concern across the world. Recent research has found multiple commonly used rapid antigen tests have diagnostic sensitivities below 30%, with sensitivities at or near 0% the first 48 hours of infection, when using polymerase chain reaction (PCR) test positivity as the gold standard. Common rapid antigen test sensitivities are lower in individuals previously infected with COVID-19 or in the setting of the BA.4 and BA.5 omicron subvariants. The changes in the rapid antigen test diagnostic sensitivities is a concern with the rapidly changing Omicron variants entering the population as an effective screening tool. With the decreasing diagnostic reliability, potential detrimental effects and lack of evidence to support continued community-based testing, what is the most up to date advice for institutions and providers regarding testing? In this review, we are critically appraising the current utility of community-based rapid antigen testing for COVID-19.