The WHO recommended their use in outbreaks, for early identification of cases and to monitor disease trends. Later, and subsequent to a rapidly increasing body of studies, this recommendation was expanded by the European Commission. The European Commission recommended the use of rapid test technology for population-wide screening where the proportion of test positivity is high or very high.[6] By January 2021, the European Commission agreed to strengthen their position, advocating much greater use of rapid tests, noting that "should research prove that rapid antigen tests can be conducted by the testee themselves.... self-testing with or without professional guidance could also be considered."[7]