September 24, 2009

experts react to news of an HIV vaccine

A trial carried out in Thailand found that a combination of two vaccines lowered the risk of contracting HIV by 31.2%. This is the first significant evidence for a preventative vaccine for HIV, though experts remained cautious over the results’ interpretation.

Dr. Jasmina Saric, Sir Henry Wellcome Postdoctoral Fellow, Department of Biomolecular Medicine, Imperial College London, said:

“The outcome of the clinical trial in Thailand may suggest some degree of protection from HIV-infection. The novel combination of the two broadly neutralising antibodies seems to work on a molecular week point of the human immunodeficiency virus which can now be further targeted with the long-term aim of developing a commercial vaccine.

“Combined resources against HIV/AIDS from all fronts will still make the biggest contribution to disease prevention and include public education, medical and sexual counselling, regular testing for HIV and other sexual transmitted diseases, safe needle use, prevention of mother to child transmission and screening of blood supply.

“An analysis by UNAIDS and the World Health Organization has shown that the power of these already existing prevention strategies cannot be emphasised enough and could, indeed, half the 62 million HIV-infections that have been predicted to occur between 2005 and 2015 – a prognosis that puts the vaccine-success into a realistic proportion until the protection has become more substantial.”

Prof Robin Shattock, Professor of Cellular and Molecular Infection, St George’s, University of London, said:

“This trial is very promising as it is the first to show a positive effect. It is early days and we need to see if the results are statistically significant. But it does gives researchers a real boost at a time when some were questioning whether a vaccine would ever be possible. Although it is very early to say exactly what this means for the future, it does offer hope.

“Now we need to understand how some of the participants in this trial were in some way protected. It is essential to discover how this experimental vaccine affected the immune response of the participants. Once we understand what worked we can build on that to develop more effective vaccines.

“At St George’s, we are already looking at next generation approaches where we deliberately target the immune response in the genital tract. Our hope is that if the current vaccine shows some protection by stimulating an immune response in the blood, then stimulating an immune response in the genital tract where the virus first infects an individual may be even more effective.”

Dr Adriano Boasso, Wellcome Trust Research Fellow, Division of Investigative Science, Imperial College London, said:

“HIV was identified more than 25 years ago as the virus that causes AIDS. Since then the possibility to prevent the infection using an effective vaccine has been unanimously consider the best possible approach to tackle the pandemic.

“Today, it was announced that a small step forward may have been made along that path. A large clinical trial, combining two vaccines which had previously given negative results when used independently, provided the first evidence that some extent of protection from HIV infection may be achieved in humans.

“The vaccine was tested on approximately 8000 adults in Thailand, whereas another 8000 adults received a placebo. Only 51 individuals became infected among those who received the vaccine, against 74 among the ones who received the placebo. This is a small difference and should be treated with caution, but it certainly represents a small and encouraging step. Thus, even if not a breakthrough in itself, this result and those which will come from more in depth analysis of the effect of the vaccine on treated subjects, may provide new directions to follow on the way to developing an effective preventive vaccine.”

Prof Aine McKnight, Professor of Viral Pathology at Queen Mary, University of London, said:

“For the past quarter of a century the scientific community has been divided on the question of whether a vaccine against HIV could be produced. Today that question is settled with the announcement of the positive results of this trial.
“This is very exciting news, but the battle is far from won. This work, and the volunteers in Thailand, have made an important contribution to combating HIV/AIDS.”