Ottawa (ECN) - Scientists announced that a study conducted among 16,000 volunteers in Thailand, unveiled in September, showned a 31.2% reduction of risk of HIV infection among heterosexuals aged 18-30
The full results of this study were to be presented Tuesday as part of the Aids Vaccine 2009 Conference, being held this week in Paris. They are also published in The New England Journal of Medicine.
"This study becomes a landmark. You can put it on a map and begin to figure out where you go from here," said Col. Jerome Kim, the U.S. Army doctor who co-led the trial.
"It's important that people understand that this is a scientific advance, a scientific breakthrough.
"It is not a public health breakthrough; there is not a vaccine that is around the corner.
"We now, after 26 years of trying, believe that we can go down that road with confidence that we will be able to develop a vaccine that is globally effective.
He however stressed that this effect is small and difficult to interpret, insisting that the marketing of the vaccine tested was still far from feasible. Not to mention that this vaccine might not work in Africa, the continent hardest hit by the AIDS epidemic.
Nearly 33 million people worldwide are HIV positive, according to latest data released by UNAIDS. An estimated 25 million people died of AIDS worldwide since the epidemic began in the early 1980s.
The study was conducted by the Thai Ministry of Public Health with support from Sanofi-Pasteur, and funded by the United States, including the U.S. Army.
It was to test an experimental vaccine result of the combination of two vaccines: the ALVAC Sanofi-Pasteur - which consists of HIV genes included in the virus canary pox, harmless to humans - and the Aidsvac, a vaccine that had previously been ineffective alone. Developed by VaxGen and Genentech, Human Aidsvac are now held by the organization nonprofit Global Solutions for Infectious Diseases.
The analysis
A few days after the announcement of preliminary results, occurred in an unusual way at a press conference in Bangkok, the researchers cited anonymously in the journal Science and The Wall Street Journal had doubts about their reliability, suggesting that the vaccine efficacy was indeed lower advances. The questioning focused on the statistical methods used to analyze the data.
The authors of the study conducted three tests.
One, called "intent to treat", takes into account all participants, regardless of their adherence to protocol. The second, "in modified intent to treat", based on the same principle but seven volunteers were excluded a posteriori, the researchers discovered they had been infected with HIV before receiving the vaccine. The third approach, called "Per Protocol", takes into account that people who strictly followed the protocol.
According to Dr. Kim, the analysis in modified intent to treat is the most accurate. But scientists have expressed doubts about these results in the press have said that the results concerning the effectiveness of the vaccine were not statistically significant after an analysis per protocol analysis and intention to treat.
The doctor at the U.S. military said that his team had responded to this question in the article published in The New England Journal of Medicine
Indeed, in an editorial accompanying the study, Dr. Raphael Dolin, Harvard Medical School in Boston, believes that this test was designed and conducted rigorously.
Several points remain to be clarified, including the duration of protection conferred by the vaccine and the respective contribution of ALVAC and Aidsvac the effect of the vaccine.
Image Credit: aides.org
