Dr. Michael Mina:

If antigen tests were widely available and people had access to them, and in particular if a government used these tests and devised a programme around them whereby they would be used two hours before an event, or twice a week if children were going back to school, or whatever it might be, these tests could keep down spread to a minimum. An epidemiological term that most people will have heard by this point is the R nought, or reproductive, number of the virus. If that can be kept below 1, outbreaks will not take off. Some people have thought that in order for a test programme to be effective, it needs to stop 100% of transmission, but that is a poor way to examine a population effect. All we have to do to prevent outbreaks from occurring in a population at large is to ensure that for every ten people who are infected, nine others will go on to be infected from those people, instead of 13. If the ratio can be kept below 1, outbreaks cannot take off. That is the basic principle of controlling outbreaks in epidemiology-----