HIV vaccine 'reduces infection'

Bottle_of_Smoke

An experimental HIV vaccine has for the first time cut the risk of infection, researchers say.
The vaccine - a combination of two earlier experimental vaccines - was given to 16,000 people in Thailand, in the largest ever such vaccine trial.
Researchers found that it reduced by nearly a third the risk of contracting HIV, the virus that leads to Aids.
It has been hailed as a significant, scientific breakthrough, but a global vaccine is still some way off.
The study was carried out by the US army and the Thai government over seven years on volunteers - all HIV-negative men and women aged between 18 and 30 - in parts of Thailand.....
.....
...Participants were tested for HIV infection every six months for three years.
The results found that the chances of catching HIV were 31.2% less for those who had taken the vaccine - with 74 people who did not get the vaccine infected and 51 of the vaccinated group infected.
The vaccine is based on B and E strains of HIV that most commonly circulate in Thailand not the C strain which predominates in Africa.

This seem significant to anyone? the difference in numbers appears tiny and probably down to chance.

It doesn't say if the groups were average citizens or high risk groups which is a bit annoying.

tallaght01

You'd need to see the paper to work out whether the trial was powered to detect that kind of difference in the groups. The lower the baseline incidence, the more people you need to detect differences in the groups.
You don't have a reference, do you?

I'm sure a HIV vaccine is only a matter of time. But I just want to know if I'm going to be out of work sooner rather than later, a I'm doing a HIV sub-specialty! :P

Captain Furball

tallaght01 wrote: »

You'd need to see the paper to work out whether the trial was powered to detect that kind of difference in the groups. The lower the baseline incidence, the more people you need to detect differences in the groups.
You don't have a reference, do you?

I'm sure a HIV vaccine is only a matter of time. But I just want to know if I'm going to e out of work sooner rather than later, a I'm doing a HIV sub-specialty! :P

<conspiracies theories stuff edited out by tallaght01>

eth0_

When I heard about this study on the news it made me feel really uncomfortable. It sounds ethically dubious, no?

Let the placebo group think they've had a HIV vaccine and they may become more sexually reckless and could end up contracting the HIV virus as a result...!

tallaght01

The placebo group don't think they are getting a HIV vaccine. They know it's experimental, and that they mightn't even get anything.

I know when I consent people for a simple swine flu vaccine trial, where they also get randomised, the consent lasts about 45 mins. These trials usually have sexual health counselling running concurrently.

Plus risk in HIV is more complex than that. For example, we know circumcision provides significant protection for males from HIV infection. BUt there has never been any evidence that once these guys are circumcised, they engage in more risky behaviour.

Most HIV infection occurs in women (though that's not the case in Thailand). These women usually don't have much of a say in their risk profile. If your husband or boyfriend wants sex without a condom, then that's what happens. For a huge proportion of HIV sufferers, their only risk factor is being a woman in a relationship with a man.

There's lots of thoughts about risk. But it seems sexual health risk doesn't vary too much within the same individual. If you're a guy in Thailand who likes to have unprotected sex, then that's what you'll do if you get the chance. It's not an evaluation each time you have sex. It's a behavioural trait. There's no great evidence of that from a psych point of view, but the epidemiological evidence suggests that's the case.

So, I would be very surprised if this trial altered the risk profile of anyone who was enrolled.

But it will be interesting to see it. The paper hasn't been published yet. BUt they're presenting at a European conference soon.

Bottle_of_Smoke

Sorry, never included link for article - http://news.bbc.co.uk/1/hi/health/8272113.stm