Suspected Saliva Results, page-12

Rapid antigen test screening can identify asymptomatic cases and stop SARS-CoV-2 transmission. This is especially important when community prevalence is high. Let's say an antigen test has 80% sensitivity and 97% specificity. When prevalence increases to 10%-20%, acceptable criteria for the PPV increases to 75%-87% and the NPV remains high (95%-98%). In essence, for the different sensitivities used, the NPV remains above 98% until reaching a prevalence above 10%. However, the PPV varies largely for a prevalence when it goes below 5% prevalence.The performance characteristics selection of antigen tests should be based on the prevalence of SARS-CoV-2 in the population being tested. WHO recommends test sensitivity ≥90% and test specificity >99%. Competing interests: No competing interests29

March 2021K.S Lam Pharmaceutical Statistical Analyst Singapore

I recall Professor Mary Louise Mclaws stated some rapid antigen tests were better at picking up asymptotic people. Trying to find it.