Questions and responses have been lightly edited for clarity Dr. Catherine Schuster Bruce: What is the difference between PCR and rapid antigen testing? Professor Iain Buchan: Lateral flows have a different role to PCR. With lateral flow, you get rapid results. The test comes to people, rather than people going to get a test. There is sufficient biological evidence that this is a useful test of infectiousness. PCR detects whether you have been infected. What is the role for mass rapid antigen testing? Public health measures very quickly need to be able to identify those who have the virus, and are infectious, so that infectious people can then quickly self isolate [for at least 10 days], and close contacts can quickly self isolate too.