those Asian countries, Japan, Korea, China, Taiwan, Singapore and HK. Korea tested 340,000 people, only 9,000 of them are infected. Even you take a look at Wuhan, the ground zero of this pandemic, seems it’s going fare better than NY. I think wearing face mask culture in those countries really help them.
The science behind this cure is that it is not that if you catch virus or not, it is that how much of virus you catch matters, i.e. the viral dose matters. The infection process is a race. Once invaders enter our body, our body starts to produce defense agents. So, it is a race between invader (virus) and our defense agents. If invaders are fewer, our defense agents will get upper hand and defeat invaders. If invaders are huge, i.e. a high dose, they will defeat our body defense agents. Then we get infected. Wearing face mask may not prevent you from getting virus, but it will help you get a low viral dose that your body can defeat them.