I don't want to pay for more vaccinations if I don't need to! What vaccinations did you get before your trip to Asia? I have been recommended to get Hep A/B, Typhoid, Japanese Encephalitis, and Rabies vaccinations.
It depends on exactly where you plan to go. You should consult a travel medicine doctor and s/he will assess your risks dependent on your itinerary and the time of year. This is an important part of travel planning which you should not skip.
Anti-malarial pills are important in several parts of SE Asia, particularly rural areas. Typhoid vaccination is smart for SE Asia. Vaccination against hepatitis A and B is wise regardless of where you travel. Dukoral is a good oral vaccine to take against cholera and E. coli - it tastes terrible but it works. Nice to haves, but not essential for SEAsia: vaccines for rabies, meningitis, Japanese encephalitis.
Everyone, regardless of whether they travel, should also have, every 10 years, vaccinations against tetanus, diphtheria and polio, and an annual flu vaccination. over 4 years ago