Field evaluation of a commercially available COVID-19 rapid antigen test kit

Filtering out of infectious individuals to interrupt the chain of transmission is the major strategy for control of COVID-19 pandemic. Rapid antigen testing is a useful tool to achieve this purpose. We evaluated a commercial rapid antigen test kit (STANDARD Q COVID-19 Ag test, SD Biosensor, Republic of Korea) which was supplied by the Ministry of health, Sri Lanka for COVID -19 testing, at field level in the Eastern Province of Sri Lanka. We tested 40 known COVID-19 positive asymptomatic persons and 143 asymptomatic vendors working in a congested public market, regarded as a high-risk location using STANDARD Q COVID-19 Ag test and the gold standard real-time RT-PCR on simultaneous samples according to the manufacturers’ instructions. The overall sensitivity of the STANDARD Q COVID-19 Ag kit was 58.5% (95% CI: 44 , 72) which increased to 79.4% in people with high viral load (Ct<25). Specificity of this kit. in our study was 100%. We recommend rapid antigen test as a primary screening test for community surveillance as it is a cost-effective measure of pandemic control.