London, October 21 (ANI): The result of the first HIV vaccine test, which was deemed to be a success last month, has now been assessed as having a modest effect.

The US Military HIV Research Program (MHRP) had made the announcement of success claiming that their vaccine reduced the risk of infection by about 31 per cent in research in Thailand.

However, the result was based on a weak number of cases, as just 51 of 8197 vaccinated individuals became infected with HIV compared with 74 of 8198 unvaccinated people, a difference of just 23.

Now, MHRP researchers have presented an analysis in accordance to their earlier finding, and two additional analyses of the raw data (PDF) at the AIDS Vaccine 2009 meeting in Paris, reports New Scientist.

Apparently, the new analyses included people who had been excluded from the research results, like the ones who had not taken the six vaccine shots in the correct order.

Seth Berkley, chief executive of the International AIDS Vaccine Initiative, said: “Certainly, there’s some kind of signal there. It’s a modest effect.”

The result observed that risks of infection in the vaccinated group were reduced by around 60 per cent within a year, but by 30 months after vaccination the protective effect was only 36 per cent. This resulted in a 31 per cent figure overall.

Berkley added: “It looked like there’s an early effect that wanes with time. It may be that the vaccine generates only weak antibodies against HIV, and these are only effective early on.”

However, the researchers are now hopeful that the investigation of the mechanisms by which the vaccine worked helps them in developing more potent vaccines.

The study has been published in the New England Journal of Medicine. (ANI)