Testing to help slow the spread of SARS-CoV-2 asks not whether someone has RNA in their nose from earlier infection, but whether they are infectious today. It is a net loss to the health, social, and economic wellbeing of communities if post-infectious individuals test positive and isolate for 10 days. In our view, current PCR testing is therefore not the appropriate gold standard for evaluating a SARS-CoV-2 public health test… There is no international standardisation between laboratories and assays, leaving Ct calibration with viral load poorly reported and easy to misunderstand.”

Mina, M.J., Peto, T.E., Garcia-Finana, M., et al. Clarifying the Evidence on SARS-CoV-2 antigen rapid tests in public health responses to COVID-19. The Lancet. 17 February 2021. https://doi.org/10.1016/S0140-6736(21)00425-6.