The partners of people who have HIV can protect themselves from infection by taking a once-daily pill, two groundbreaking studies in Botswana, Kenya and Uganda have shown.
The discovery could bring work to combat Aids close to a "tipping point", experts say. Attempts to promote condom use to protect against HIV in the hardest-hit parts of the world, and particularly Africa, have hit cultural barriers and had limited success.
But now it appears that men or women who know – or suspect – their partner has HIV could protect themselves, secretly if necessary. The larger study, involving 4,758 "discordant" couples (where one has HIV but the other has not) in Kenya and Uganda, led by the University of Washington's International Clinical Research Centre, shows that those taking a single daily tablet of the Aids drug tenofovir had 62% fewer infections and those who took a pill combining tenofovir and emtricitabine had 73% fewer infections than those who took a placebo pill.
The drugs have few side-effects, which is important if they are to be given to healthy individuals. Both are made by Gilead, which has licensed their manufacture to generic companies in the developing world, allowing them to produce cheap copies – so this is a relatively inexpensive intervention.
"This study demonstrates that antiretrovirals are a highly potent and fundamental cornerstone for HIV prevention and should become an integral part of global efforts for HIV prevention," said Dr Connie Celum, professor of global health and medicine at the university and principal investigator of the study, known as the Partners PrEP Study, which was funded by the Bill and Melinda Gates Foundation.
The second study in Botswana was conducted by the United States Centres for Disease Control. It followed 1,200 heterosexual men and women without HIV who received either a once-daily tenofovir/emtricitabine tablet or a placebo pill. The antiretroviral tablet reduced the risk of acquiring HIV infection by roughly 63% overall.
"This is a major scientific breakthrough which re-confirms the essential role that antiretroviral medicine has to play in the Aids response," said Michel Sidibé, Executive Director of the Joint United Nations Programme on HIV/Aids (UNAids). "These studies could help us to reach the tipping point in the HIV epidemic."
The news follows hard on the heels of another very significant finding – that people with HIV who are taking combinations of antiretroviral drugs not only stay healthy themselves but are unlikely to infect their partner.
The two pieces of research give a massive boost to the cause of rolling out more Aids drugs and treating people at the earliest stage of their illness.
"Effective new HIV prevention tools are urgently needed, and these studies could have enormous impact in preventing heterosexual transmission," said Dr Margaret Chan, WHO's director general. "WHO will be working with countries to use the new findings to protect more men and women from HIV infection."
