The combination of two vaccines that has previously failed to produce a response on their own has cut the risk of becoming infected with HIV by more than 31 per cent.
It is the first time in human trials that a vaccine has protected against the virus which leads to Aids.
The vaccines are ALVAC, from Sanofi Pasteur, the vaccine division of French drugmaker Sanofi-Aventis; and AIDSVAX, originally developed by VaxGen Inc. and now held by Global Solutions for Infectious Diseases, a non-profit founded by some former VaxGen employees.