You can always check the CDC Health Information for Travelers to Southeast Asia.

None required, it doesn't look like, but some are recommended by the CDC at least. Tetanus booster is a good idea in general if you're past 10 years on it, and Hepatitis A might not be a bad investment since southeast Asia lies in a 'high risk' zone. They recommend a typhoid vaccination, but I'm not sure how serious that actually is.

There's some others (hep B, Japanese encephalitis, rabies) recommended only under certain circumstances.