The standard voltage in Vietnam is 220V. There are three plug types in Vietnam: Types A, B and C.
It's recommended to have gotten the following vaccinations before visiting Vietnam: Measles-mumps-rubella, diphtheria-tetanus-pertussis, chickenpox, polio, and your yearly flu shot. Additional vaccinations you should get for Vietnam are: Hepatitis A, Typhoid, Japanese Encephalitis, Hepatitis B, Malaria and Rabies. We recommend double checking with the CDC or your doctor for more information about vaccinations you need before your trip.
Credit cards are accepted in most hotels, restaurants, and shops in Vietnam but generally speaking, cash is king here, especially in less touristy areas.
These are the holidays celebrated in ベトナム: