[Jotaku]

Well I was in South Korea just few weeks ago, where is ranked at top 4 in the world in terms of the number of people infected, so let me just share what is the most recommended to prevent it there.

1. Use KF94 mask or 3 layer mask that has waterproof that prevent spits or N95 mask (You can get them on ebay.com). KF94/N95 will work better than 3 layer. In any case, normal cheap cotton mask won't work because they can't prevent spits. Discard each mask if you used for 3 days.

2. When you grab the mask, only grab using earloop. Do not touch elsewhere.

3. Wash your hand a lot often, for 20~30 seconds with soap. If you can't, get portable hand sanitizer and use it frequently.

4. Do not touch any of your face (especially around eyes, nose, and mouth) unless you just washed your hands and touched nothing.

That's it. Finally I am now in north america region again, and has none of any symptom after 2 weeks, which is now.
Hope it helps.

[Jotaku]

Well looks like the way written above works good since coronavirus live counter recently shows that Korea has been dropped to outside of top 10 from top 4 for doing above for last few months.