AN EXPERIMENTAL H.I.V. VACCINE FAILS IN AFRICA Researchers en | The New York Times

AN EXPERIMENTAL H.I.V. VACCINE FAILS IN AFRICA

Researchers ended a large trial in South Africa after finding that an experimental vaccine offered little protection.

Over two years, 63 of 1,109 participants who received the placebo were infected with H.I.V., compared with 51 of 1,079 participants who received the vaccine — giving the vaccine an efficacy rate of 25 percent, which was very disappointing.