Prime-boost trial begins in Thailand

Thailand began immunizations for its second Phase III AIDS vaccine trial on 20 October. This study will test a combination of two vaccines called ALVAC and AIDSVAX in about 16,000 HIV-negative people who will be followed for approximately three and a half years. Trial co-sponsors include US Military HIV Research Program and Mahidol University in Thailand. The trial will take place in 8 districts in Thailand.

ALVAC vCP1521 is a candidate that combines small fragments of HIV genetic material with a virus called canarypox that normally infects birds. Previous trials have shown that canarypox-based vaccines are safe for use in humans. The AIDSVAX candidate has been tested alone in two large-scale trials (see above) but has not shown any protection. Sponsors say that the current trial is still going ahead because it is possible that the vaccines will provide some protection when used in combination.