In what some are calling a historic day in HIV prevention, a microbicide gel has been found to help prevent HIV transmission.The results of clinical trials of CAPRISA 004 were formally released Tuesday at the 18th International Aids Conference in Vienna.

The trial shows the microbicide has an overall effective rate of 39 percent.  While more study is being done, it could lead to a convenient and easy method for women to protect themselves from HIV during sexual intercourse.  CAPRISA 004 contains the antiretroviral drug Tenofovir.

Among those praising the results is Mitchell Warren, head of the AIDS Vaccine Advocacy Coalition (AVAC).  Warren, who?s attending AIDS 2010, says, ?This is a really historic day for HIV prevention research.  For the first time, though the CAPRISA 004 trial, we have seen evidence in a human clinical trial that a microbicide can help to prevent sexual transmission.?

What does it mean?

Warren says 39 percent ?is perhaps not strong enough to immediately roll it out as a product.  But it is the first proof of concept.  And for the first time in the history research we can say that a microbicide can work against HIV.?

While the 39 percent is the overall efficacy rate for the trial, the results also show that women who strictly adhered to the instructions on using the gel had a 54 percent efficacy rate.

?Microbicides are user controlled.  By which we mean it only works if the user uses it.  We talk about condoms.  They?re 97 percent effective, but they only work if they?re used correctly and consistently.?

CAPRISA 004 Discovery Marks Historic Day in HIV Pr
CAPRISA 004 Discovery Marks Historic Day in HIV Prevention Research

Nearly 900 South African women took part in the CAPRISA 004 study, which was led by the Center for the AIDS Program of Research in South Africa (CAPRISA) at the University of KwaZulu-Natal.  The U.S.-based counterparts included reproductive health organizations FHI and CONRAD, with sponsorship from USAID.

?There are very small numbers of people in the trial to begin with.  So it?s hard to extrapolate, but there is a very clear indication from this trial that adherence to the product matters, that women who used a lot of it had higher protection.  The women who used less of it had lower protection,? he says.

Improving both adherence and effectiveness

Warren says it?s unclear how high the efficacy rate would have to be before medical officials and regulators would approve it for sale.

?What?s important is that this is the first trial that was looking at the effectiveness of a microbicide using an anti-retroviral.  All the previous microbicides were based on products that were not specific to HIV.  So this was a very important trial to prove the concept of ARV (anti-retrovirals)-based microbicides,? he says.

The AVAC leader says a number of methods can be considered to boost effectiveness and adherence, including different formulations, better marketing and packaging.

?The other way to boost effectiveness is to look at Tenofovir perhaps combined with other anti-retrovirals, as we have in therapy,? he says.


?The good news is that there?s another trial already ongoing of Tenofovir gel.  It?s a large study in four African countries called VOICE.  And it?s studying this Tenofovir gel when women use it daily, whereas in the CAPRISA trial women were using it in a specific dosing schedule only just before and after they had potential sexual exposure,? he says.

The results of the VOICE trial are due in either late 2010 or early 2013.

But is it possible CAPRISA 004 could be marketed to at least give women some further protection against HIV?

Warren says, ?Well, I don?t know that we know yet.  The data was just released today.  I think we?ll have a better sense of that in the coming weeks and months.?

Warren praises the South African volunteers and those who conducted the study.

He adds, ?It?s really urgent that we develop a comprehensive plan quickly that articulates all the different steps we need to take as a community to translate what is a thrilling research result into the real desire, which is public health impact.?

The 18th International AIDS Conference continues through July 23.

VOA's U.N. correspondent Margaret Besheer talks to UNAIDS Executive Director Michel Sidibe about the breakthrough in the fight against AIDS (Excerpt from "In Focus" TV program)