H.C.
Immunizations are not required for school if the parents provide a statement of objection. The most commonly accepted objection is based on religion but other reasons are also accepted. We weren't planning on getting the full round of immunizations and vaccines for our son but we were living in NM at the time. His doctor (a DO) isn't one of those types to prescribe antibiotics for every little sniffle...but she STRONGLY recommended that we get him the full CDC shot schedule. This was because in NM, there are lots of folks who have "questionable" legal status in the US and thus less than adequate healthcare plus diseases like human plague (yes meaning the bubonic plague) still occur in that state! So, the doc recommended the full CDC shot schedule as a self defense measure.
Now as for traveling to China--first thing to do is check the CDC Travelers' Health website and read the Yellow Book information on health risks and current disease outbreaks in China and southeast Asia.
CDC Travelers' Health
http://wwwn.cdc.gov/travel/default.aspx
China specific information
http://wwwn.cdc.gov/travel/destinationChina.aspx
So without any vaccines I would forego asking his doctor but rather go to a Travel Medicine Specialist.
http://wwwn.cdc.gov/travel/contentTravelClinics.aspx
Travel Medicine clinics will have the most current information about vaccine and immunization requirements. Plus, they are able to administer the needed shots. Note that shots are most effective if administered 4-6 weeks prior to travel. We use a TM specialist for all our travel health needs prior to international trips.
In looking at the Yellow Book information, there are no mandatory vaccines but the usual Hep A, Hep B, Typhoid, rabies and Japanese encephalitis immunizations are recommended ESPECIALLY if you are traveling to more rural and less developed areas. But traveling to major metro areas like Shanghai, Beijing or Hong Kong should pose no extra health hazard than traveling to LA, NYC or Atlanta.