Vulnerable virus

Researchers have shown that a vaccine against HIV is possible in principle. In the largest and most expensive HIV vaccine study to date, the infection rate among the volunteers who received the vaccine was around 30 % lower than that of the control group. UNAIDS considers these trial results very encouraging.

However, critical scientists, who were not involved in the study, are already putting the results into question, saying that the level of protection was of 26 % at most. “For the first time in 20 years of scientific experimentation, we now have something that seems to suggest a vaccine might work,” is how Andreas Wulf of the non-governmental organisation medico international puts things into perspective. After a study conducted by Merck & Co. in 2006, general scepticism prevailed about an anti-AIDS vaccine being feasible at all. Instead of reducing the risk of infection, the vaccine tested in the Merck trial actually increased it.

The recent large-scale test involved more than 16,000 volunteers in Thailand aged between 18 and 30 with an average risk of infection. Over a period of six months in 2006, they were given either the vaccine or a placebo. In late September, the not-for-profit agency Global Solutions for Infectious Diseases (GSID) reported 74 cases of infection in the control group but only 51 in the group that had received the vaccine. This difference only barely qualifies as statistically significant. Some scientists say the divergence is within the realm of pure chance. GSID is funded by the Bill and Melinda Gates Foundation, among others. The main sponsor of the study was the US Army.

At present, the trial results offer only a glimmer of hope. Important matters are still unknown. The vaccine is based on two active ingredients that had no effect when tested on their own. Why did that change when they were combined? The study is based on strains of HIV common in Thailand. Will the potential vaccine work elsewhere? Scientists still have a lot of work to do.

Most important, however, a 30 % risk reduction is not enough for a vaccine. “Even 60 % is only modest,” says medico expert Wulf. Any HIV vaccine that does not provide close to 100 % protection would give people a false sense of security.

Until science comes up with a reliable HIV vaccine, public-awareness campaigns remain the best form of protecting people. To help promote a responsible approach to the subject, UNESCO and the Asia Pacific Institute for Broadcasting Development have produced a manual for TV journalists. It is available for downloads from the Internet free of charge. (cir)