Coronavirus' 4 layers of Defense

Описание: A community can protect itself with 4 layers of defense against the coronavirus:
1. Don't get infections inside your community
2. If they do, prevent them from meeting other people
3. If they do meet other people, prevent them from spreading the virus
4. If they do spread it, identify the infected and neutralize them.

None of these 4 layers are perfect.
They can't stop the virus by themselves.
But together they can.