On Sept. 28, 2020, as COVID-19 infections began to rise again, a novel testing strategy was proposed by researchers at the University of Oxford at the start of the pandemic became urgent once again. The strategy aims to bring the virusﾒs reproduction number (ﾑRﾒ) down to below 1, by concentrating testing resources on particular groups in the population that are most likely to spread the infection to others, rather than testing the general population at random.

The proposed strategy is predicated on the understanding that not everyone is equally likely to spread COVID-19. An individualﾒs likelihood of infecting others will depend on their occupation, geography, and other behaviours when not isolated.