Scaling up COVID-19 rapid antigen tests: promises and challenges

WHO recommends a minimum of 80% sensitivity and 97% specificity for antigen-detection rapid diagnostic tests (Ag-RDTs), which can be used for patients with symptoms consistent with COVID-19. However, after the acute phase when viral load decreases, use of Ag-RDTs might lead to high rates of false negatives, suggesting that the tests should be replaced by a combination of molecular and serological tests. When the likelihood of having COVID-19 is low, such as for asymptomatic individuals in low prevalence settings, for travel, return to schools, workplaces, and mass gatherings, Ag-RDTs with high negative predictive values can be used with confidence to rule out infection. For those who test positive in low prevalence settings, the high false positive rate means that mitigation strategies, such as molecular testing to confirm positive results, are needed. Ag-RDTs, when used appropriately, are promising tools for scaling up testing and ensuring that patient management and public health measures can be implemented without delay.

Automated summary

WHO recommends antigen-detection rapid diagnostic tests (Ag-RDTs) with at least 80% sensitivity and 97% specificity for patients with symptoms consistent with COVID-19. Ag-RDTs may show high false negative rates after the acute phase, suggesting the need for a combination of molecular and serological tests. In low prevalence settings and situations where infection needs to be ruled out, Ag-RDTs with high negative predictive values can be used confidently, but high false positive rates in low prevalence areas require further confirmation.