evidence: Other indirect evidence comes from studies that have documented associations between self-reported mask wearing and control of the virus in a community, or the implementation of a mask mandate and a subsequent decline in COVID-19 cases or rates of hospitalization. [...] In Kansas, which instituted a mask mandate in July but allowed counties to opt out, the number of new COVID-19 cases per capita fell by 6% in areas with mask mandates, but rose by 100% in those without. Another study in the U.S. did not identify an impact of a mask mandate, but found that a 10% increase in self-reported mask usage was associated with a state being 3.5 times more likely to have control of its epidemic.