Other example is Taiwan. Everybody wears a mask there since the first cases. We don't know for sure it's the reason why they have so few cases but there are good reasons to believe so. I had friends there and thought I was smart telling them it was useless to wear a mask without symptoms (which was actually WHO recommendations)... Maybe WHO recommendations took into account the fact that masks weren't in sufficient quantities. For this strategy to work, you need enough mask for everybody, otherwise people would start hoarding masks. Maybe this will be the strategy post-confinement.