* Women used gel reliably, but further testing needed
* WHO chief says findings are “exciting”
* UNAIDS HEAD says results “give hope to women”
(Adds reaction from WHO, experts AIDS meeting, previous VIENNA)
VIENNA, July 19 (Reuters) - A gel containing a prescription drug can sharply reduce HIV infections in women, a study described as groundbreaking by the World Health Organisation showed on Monday.
The gel, containing Gilead Sciences (GILD.O) AIDS drug tenofovir, reduced HIV infections in women by 39 percent over two and a half years -- the first time such an approach has protected against sexual transmission of the virus.
The findings, presented at an international AIDS conference in Vienna, were described as “groundbreaking” by the World Health Organisation and the United Nation’s AIDS group (UNAIDS).
They show it may be possible to slow the spread of the disease by giving women a way to protect themselves.
“Boy, have we been doing the happy dance,” Dr. Salim Abdool Karim, from the University of KwaZulu-Natal in Durban, said of the South African findings.
The gel also cut the risk a woman would get genital herpes by 51 percent, a surprise result that adds further benefits.
The trial of 889 women in the coastal city of Durban and a remote rural village showed women largely used the gel as directed, Karim said, answering an important question about whether such a product could work in the real world.
Shares of Gilead were up 3 percent at $32.90 in afternoon trading on the Nasdaq exchange.
The study was funded by the South African government and USAID. Gilead supplied the drug for no charge but was not otherwise involved.
Margaret Chan, director general of the WHO, described the findings as “exciting”.
“We look forward to seeing these results confirmed. Once they have been shown to be safe and effective, the WHO will work with countries and partners to accelerate access to these products,” she said in a statement to the Vienna conference.
UNAIDS director Michel Sidibe, also at the conference, said it could become “a powerful option for the prevention revolution and help us break the trajectory of the AIDS epidemic.”
Researchers have been trying for years to formulate a microbicide -- a gel, cream, ring or tablet inserted into the vagina or rectum before sex to prevent transmission of the human immunodeficiency virus that causes AIDS.
But past efforts have had disappointing results.
In this test of a microbicide, called Caprisa, researchers used for the first time a prescription HIV drug in the mix, Gilead’s tenofovir. Studies in monkeys have strongly suggested it can protect against both vaginal and rectal infection.
In Africa, where most of the world’s 33 million HIV cases are, most new cases are in young women infected by older men. Young boys aged 15-19 do not have high rates of HIV, but girls this age already do.
The Caprisa trial was a classic medical clinical study, with half the women using the gel before and after sex, and half being given a placebo. No one knew who got the real drug.
The women kept track of the applicators, which resemble applicators used to insert tampons, and gave them to researchers so they could be sure when the gel was actually used.
All the women were also given condoms and advice about sexually transmitted diseases, and tested for HIV once a month.
After 30 months, 98 women became infected with HIV -- 38 in the group that got tenofovir in the gel and 60 in the group that got placebos. “We showed a 39 percent lower incidence of HIV in the tenofovir group,” Karim said.
When they checked the data, it turned out that tenofovir lowered the risk of infection by 50 percent at 12 months but then the efficacy declined. Women who used the gel more consistently were much less likely to be infected.
“Why is our effectiveness going down over time? Essentially it is a matter of adherence,” Karim said. “We are telling these women we have no idea if this works and we are also telling them we don’t know it is safe.”
If women understand the gel will protect them Karim said, he believes they will use it more consistently. He added he did not know how much each dose would cost but said the applicators and gel cost just pennies.