New HIV vaccine cuts infection by a third
Updated
Results from the world's largest ever HIV-vaccine trial have been announced in Thailand - with the momentous news that the vaccine cuts the risk of infection by a third. The UN says it's the first time a vaccine has offered significant protection for adults against HIV, the virus that causes AIDS. The trial was a joint initiative of Thailand's Ministry of Public Health and the US Army, who worked with more than 16,000 volunteers whose lifestyles exposed them to the virus. The scientists say the trial suggests one in three people who received the vaccine was protected from infection as a result.
Presenter: Corinne Podger
Speaker: Michael Bartos, head of HIV Prevention Team, UNAIDS, Geneva
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BARTOS: Yes precisely so in the results which have been released what is evident is that for every 100 people who received the vaccine in this case in the trials circumstance, then 30 people would not get infected. So that's the sense in which it's 30 per cent efficacy.
PODGER: Is there any idea why it's not fully effective?
BARTOS: No I think that's one of the key scientific questions which arises from this study. So it is obviously a very encouraging result, but precisely how the mechanism of protection works, why it works with some people and doesn't work with other people, that is precisely the scientific question which these results now raise, and that is what is both enormously interesting to AIDS vaccine scientists around the world and the most important further question to be looked at in the connection with this trial result.
PODGER: It's a combination of two older vaccines, neither of which was terribly effective. Was it a surprise to everyone that this new combination actually worked?
BARTOS: I think it's probably true to say that it was a surprise. The expectations of these results here were probably I think that there were not going to be any sort of positive results at all, so there certainly is a sense that the result here was a surprising result. I think it's also true that in terms of looking at how the two vaccines worked in combination, it's true that in a sense in exactly the same way that for anti-retro-viral therapy, the breakthrough was made when combination therapy arose. That's one of the reasons why there is an interest in combining different approaches of things that HIV is susceptible or has to be attacked from more than one direction at the same time. So I think that's the sense in which people have always been interested in using combined approaches, which will attack the virus from two different directions at the same time. This is the first time this has proved to be effective at all in the context of an AIDS vaccine. And so that's why there's an enormous amount of interest in this approach. But exactly how the two vaccines work together and what exactly they do is really the subject of inquiry now.
PODGER: And interest not just from the scientific community but obviously on the ground as well. I understand it may only be effective against the form of the HIV virus in Thailand, so is it too early to talk about commercial production?
BARTOS: It's very much too early to talk about commercial production and in fact this trial was not designed to be a trial of a product to start going into production of. It was in fact a proof of concept. So it was in fact a scientific inquiry to see whether conceptually there would be any sort of result from combining these two vaccines in this sort of way. That's the sense in which it's encouraging, but it's also very early days in terms of there being any thought of moving to the next stage, which is in fact to trial something at a mass scale, of something to see whether it works in a population as a whole and then to move on from that to the next stage, which is the commercial production of a vaccine. So in that sense it really is at a reasonably early stage of development. The reason people are so excited and encouraged by these results is they're the first glimmer of positive results in HIV vaccines for a long time, despite the fact that this field of inquiry has been going since, almost since HIV itself was first identified. So that's the sense in which we were encouraged, but it is still very early days in relation to these results.
