Fast and decisive.
Fast:
Vietnam is the second country (after U.S.A.) to block the entry of people from China. There is a relative long border line between China and Vietnam and the traffic between China and Vietnam is very heavy. So the danger of the virus is very great. Vietnam is fast enough to block the people crossing the border.
Decisive:
1. Blocking the Chinese has been carried out very effectively (while similar work done by U.S.A. is just a joke).
2. Lock down has been carried out fast.