evidence: A Cochrane Review shows that compared with no facemask use, wearing a facemask may make little to no difference in how many people that catches a flu‐like illness. It probably makes little to no difference in how many people that have flu confirmed by a laboratory test. Unwanted effects are rarely reported but include discomfort. Furthermore, it may seem that it makes little to no difference what type of facemask is used. This Cochrane Review searched for studies in April 2020 and does not include studies on COVID-19. The evidence presented here can thus not be considered as direct until COVID-19 studies are included in the analyses. This Cochrane Review shows that compared with no facemask use, wearing a facemask may make little to no difference in how many people that catches a flu‐like illness. It probably makes little to no difference in how many people that have flu confirmed by a laboratory test. Unwanted effects are rarely reported but include discomfort. Furthermore, it may seem that it makes little to no difference what type of facemask is used. This Cochrane Review searched for studies in April 2020 and does not include studies on COVID-19. The evidence presented here can thus not be considered as direct until COVID-19 studies are included in the analyses. [...] - the use of facemask may make little to no difference in how many people that catch an influenza-like illness (low certainty)