HIV/AIDS vaccine trials results promising, UNAIDS

Preliminary results of the first HIV/AIDS vaccine to be tested on humans were "promising" and an indication that it was possible to provide a degree of protection from HIV infection, UNAIDS said on Monday.

But findings from the trials show the vaccine only reduced the rate of HIV infection by 3.8 percent, US vaccine company VaxGen said in a statement.

The trial of the company's AIDSVAX vaccine appears to show a protective effect among African Americans and Asians, although sample sizes were small. However, for the majority of the participants, the effect of the vaccine was minimal.

"These results are promising. The trial provides clear evidence that a vaccine can work. However, there is an urgent need for more targeted research to find out why the candidate vaccine only seems to work in certain population sub-groups," Dr Peter Piot, Executive Director of UNAIDS said in a statement.

The vaccine used in the VaxGen trial was designed to reduce susceptibility to infection with HIV subtype B, which is prevalent in the Americas, Western Europe, Australia, and New Zealand.

But the major challenge in HIV vaccine development is to develop one or multiple vaccines effective against all major subtypes of HIV, particularly against those in sub-Saharan Africa.

"I don't think anyone will expect much from the report, the research is extremely limited. With studies done in places where HIV prevalence is low, it is difficult to see the protective mechanism of the vaccine, which is why trials need to be done in developing countries," Dr Rosemary Musonda, a member of the African AIDS Vaccine Programme steering committee, told PlusNews.

Admitting that the AIDSVAX results were "disappointing", Dr Pontiano Kaleebu of the Uganda Virus Research Institute remained upbeat.

"This should not discourage people, rather it should encourage more people to come forward with more trials," he told PlusNews.

Several African countries are currently involved in HIV vaccine development, including Uganda, Kenya and South Africa. But AIDSVAX is the only HIV vaccine to have completed phase three clinical trials - the last step before drug companies can seek approval from drug regulatory bodies.

"We need to step up research in different countries, we need different trials with different types of vaccines. This is the only way we can get tangible results," Musonda noted.

In Uganda, the first phase of trials for a vaccine which targets the subtype prevalent in East Africa, are now underway.

"This has been a lesson for Africa. Laboratory work is not enough, we have to do more trials and move forward quickly," Kaleebu added.