An HIV/AIDS vaccine began its Phase I clinical trial at the Peking Union Medical College Hospital over the weekend. It is the second HIV/AIDS vaccine developed in China to begin tests in humans. The vaccine, a joint project of the National Center for Disease Control and Prevention and the National Vaccine & Serum Institute, will be administered to 36 volunteers. The new vaccine uses a smallpox vaccine as the carrier. Last year, another HIV/AIDS vaccine passed its Phase I trial, but no follow-up Phase II trial of the vaccine has been announced.