PM - Thursday, 8 November , 2007 18:34:00 Reporter: Lindy Kerin MARK COLVIN: Hopes for a cure for HIV-AIDS have taken a massive blow with the failure of a clinical vaccine trial in the United States.
Not only did the vaccine not work, it left participants more vulnerable to the deadly virus than before.
The trials, by the US drug company Merck, involved more than 3,000 volunteers around the world, including 19 Australians.
Before the trial started, the volunteers tested negative to HIV.
But two months ago, the researchers found that the vaccine was not effective at preventing infection. They called the trials off.
Now, further analysis has revealed that those who received the vaccine actually had a higher rate of infection than those who received a placebo.
Lindy Kerin reports
LINDY KERIN: It took almost 20 years of research and development to get the HIV vaccine known as V5-20 to human trials.
At a press conference in Seattle today, devastated researchers delivered the news that the clinical trials had increased the risk of HIV infection among the volunteers who took part in the study.
Dr Lawrence Corey is the co-director of the Vaccine and Infectious Disease Institute in the United States.
LAWRENCE COREY: One of the possibilities is that the increase in the number of infections could be related to the vaccine. There are many other possibilities as well. My own opinion is that it's way too early to really answer and the data is very complex and there's not simple answer to that question.
LINDY KERIN: 3,000 volunteers from diverse backgrounds have been involved in the trial.
They're all between the ages of 18 and 45 and at high risk of HIV infection.
The results show 21 cases of infection among almost 400 men who had the vaccine while only nine cases were reported among those who had the placebo.
Dr Margaret Johnston from the Vaccine Research Program at the National Institute of Allergy and Infectious Diseases says teams of scientists are working around the clock to find out what went wrong.
MARGARET JOHNSTON: This will not be business as usual. We're going to put as much resources behind this as we possibly can, because it is important not only… because it is important for the future of the field.
LINDY KERIN: Dr Tony Kelleher from the University of New South Wales, is in charge of the Australian part of the trial and has today contacted the 19 participants in Sydney.
TONY KELLEHER: They're all disappointed by the result. I don't think anyone enrols in a trial with the idea that the trial is going to give a negative result.
I guess the reaction vary enormously from individual to individual.
Some are reasonably distressed by the news and others are disappointed but not particularly distressed by the news.
LINDY KERIN: The vaccine uses a genetically modified version of the common cold virus that acts as a carrier to deliver small HIV components through to the blood system.
Scientists were hoping it could prevent HIV infection, or at least delay the course of progression of the virus which causes AIDS.
Dr Kelleher says it's a major setback for HIV research.
TONY KELLEHER: It was certainly one of the lead candidates for… in terms of vaccine development for HIV. So it's certainly been a significant blow to the field, and it will certainly impact on the development of other vaccines.
LINDY KERIN: Dr Kelleher says researchers will decide over the next 10 days as to whether the patients should be told who was given the HIV vaccine.
TONY KELLEHER: Neither the doctors or the nurses that administer the vaccine, nor the volunteers who receive the vaccine know whether they got vaccine or placebo. So one of the questions that's being debated at the moment by the investigators is whether the trial should continue in a blinded fashion or not or whether everybody should be told what they were allocated - so whether they received the vaccine or placebo.
What we have done when we've contact the volunteers is that if they have been distressed and if their concerns would be allayed by knowing whether they got the vaccine or not, we've offered to un-blind them, and a number of them have taken up that opportunity.
LINDY KERIN: But Dr Margaret Johnston says there's some reluctance among researchers to tell participants about what they received in the trial.
She warns it could change people's behaviour.
MARGARET JOHNSTON: I could also spin a hypothetical that if I were a vaccine recipient and uninfected and learned I got the vaccine I might say, "well, gee, I'm still uninfected even though I might be at increased risk, so therefore it must be doing something right". And then I change my behaviour. I mean, so who knows. There's an infinite number of hypotheticals that we could spin here.
LINDY KERIN: More than 25 million people have died from HIV-AIDS since the virus was first discovered in the 1980s.
Every day, about 12,000 people become infected.
It seems that developing an effective AIDS vaccine remains one of the biggest challenges in modern medicine.
MARK COLVIN: Lindy Kerin.
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