Efficacy comparison of three rapid antigen tests for SARS‐CoV‐2 and how viral load impact their performance

More and more rapid antigen tests for the diagnosis of severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) appear in the market with varying performance. The sensitivity of these tests heavily depends on the viral load, extrapolated by the threshold cycle (Ct). It is therefore essential to verify their performance before their inclusion in routine. The Coronavirus Ag Rapid Test Cassette Bio‐Rad, the GSD NovaGen SARS‐CoV‐2 (COVID‐19) Antigen Rapid Test, and the Aegle Coronavirus Ag Rapid Test Cassette were evaluated on 199 samples: 150 fresh samples from the routine and positive in quantitative reverse‐transcription polymerase chain reaction (RT‐qPCR), nine fresh samples negative in RT‐qPCR, and 40 frozen samples, taken before the discovery of SARS‐CoV‐2 but positive for other respiratory viruses. Positive RT‐qPCR samples were categorized according to their Ct: Ct