No vaccination is required but you should stay up date of your classic vaccinations (diphtheria, tetanus, typhoid, polio and hepatitis).
For rabies and Japanese encephalitis, vaccines are recommended for rural stays of more than one month, or if expatriation.
About malaria, please rest assured that there is NO malaria in big cities (Hanoi, Hai Phong, Hue, Hoi An, Da Nang, Da Lat, Ho Chi Minh City), coastal towns (Halong, Quy Nhon, Nha Trang, Phan Thiet) and Red River Delta. Check your itinerary in detail and should it takes you to these areas, you do NOT need any protection against malaria.
Also, remember to check your teeth before your departure and take with you a small first aid kit with aspirin, common cold and flu tablets, antihistamines for allergies and itches, medications for diarrhea, insect repellant, sunscreen, lip palm and some bandages. If you are having a regular prescription, bring enough for the entire trip.