The WHO lists seven molecular assays for diagnosing COVID-19; this study used RNA transcripts, isolated virus RNA, and mock clinical samples to evaluate the primer-probe sets used in the four most common assays developed by the China CDC, US CDC, Charité, and Hong Kong University. Vogels et al. found that all of the primer-probe sets could detect SARS-COV-2, but for low amounts of virus they varied in ability to differentiate between true negatives and true positives. The authors suggest there is evidence that all these assays work for virus detection but the individual limitations of each should be considered by laboratories and public health agencies when choosing assays to adopt.