Seventy-eight healthy South Africans are to test a new candidate HIV vaccine over the next 18 months, reports the Mail and Guardian. The International Aids Vaccine Initiative (IAVI) and a United States company need to determine if the medication is safe and effective. Called "tgAAC09", the preventive HIV vaccine candidate is based on HIV subtype C, the subtype of the virus most prevalent in Southern and East Africa. "The trial should take about 18 months to complete and will enrol 78 volunteers in total -- men and women -- who are in good health. TgAAC09 is designed to elicit two different types of immune responses, an antibody response and a cell-mediated response. The vaccine consists of an artificially made copy of the HI virus and cannot cause HIV infection or Aids," the IAVI said on Monday, November 14.