No vaccinations are required for travel to China. However immunisation against the following diseases is recommended: diphtheria, typhoid, tetanus, polio, hepatitis A and B (hepatitis B is widespread in China).
First aid kit
In the major Chinese cities there are pharmacies (traditional medicine and allopathic) and there is no difficulty in finding treatments for colds, digestive problems and other common minor ailments. However treatments are less easily found in the countryside especially since the medicines available are often counterfeit and cheaper than the real medicines.
Running water is not drinkable anywhere in mainland China but it is easy to purchase bottles of mineral water (kuangquanshui / 矿泉水) or purified water. Alternatively you can always find boiled water (shui kai / 开水). Some people travelling at high altitudes (usually above 3500 m) may develop symptoms of mountain sickness.
This is almost non-existent in Yunnan since most of the provincial territory lies at an altitude above which the Anopheles, the contaminating mosquito, cannot survive. Only low-lying areas south of the province have a potential risk during the rainy season. Arteannuin (qinghaosu / 青蒿素), a plant used for centuries in Chinese medicine, is now considered the most effective cure for Malaria. No immunizations are required to enter China, unless you’re coming from a yellow fever infected area.
However, it’s recommended to have current polio and tetanus immunizations as well as hepatitis A and B’s. Bring along a supply of wide spectrum Antibiotics and an antidiarrheal agent, (immodium, ercefuryl). Running water is not drinkable in mainland China but it is easy to be supplied in mineral or treated water bottles and you will always find boiled water .
More info World Health Organization’s website.