SOME companies are making a fortune in the health care business in China. Private clinics set up in major Chinese cities in recent years are charging exorbitant rates to foreigners who want Western-style treatment. Beijing's International Medical Clinic recently charged a patient US$44 for two boxes of Alka Seltzer indigestion tablets on top of the $75 for what was described as a brief office visit. Another visitor, seeking to guard against hepatitis A, which is endemic in China, went to AEA, another clinic in the capital, and was charged $70 for each of three jabs. Another expatriate complained that regular blood tests as part of treatment he was undergoing were three times more expensive than in Hong Kong.