Then use California and New York. Both implemented mandatory mask rules, and the number of cases tripled. New York has reach herd immunity, and lock down mask wearing California has not.(Policy put in place in May.) New York has reach zero deaths per million, and California is rising (with masks). The policies did nothing to reduce the rate of increase, which is why mask are not a factor if you look at the data. It's herd immunity, which is exactly the policy that Sweden actively made a choice to pursue.