evidence: And even analysing changes to cases and hospital admissions, it is difficult to pick out the effect of mask-wearing in particular. [...] A study in Kansas found local areas in the state went from having the highest numbers of cases to seeing fewer hospital admissions and almost half as many deaths after introducing mask rules, compared with those that did not, even when no other rules had been introduced at the same time. [...] One review of six studies estimated mask-wearing reduced the risk of catching Covid by 60%, and 70% among healthcare staff.