> It will test how effective the vaccine is by comparing a vaccinated and a non-vaccinated group, Kang said in the video.
So I was going to ask how clinical trials for vaccines are done, and this part kind of answers it, but now I'm curious - if there's no control group that gets a placebo injection, how do you control for the fact that people may behave differently if they think they've been given an anti-HIV vaccine? Unless I'm misreading this and "non-vaccinated" means placebo.
1) We generally know the strength of the placebo effect and the rate of HIV transmission among at-risk groups, so we can control for it, and
2) Not sure the placebo effect is particularly relevant. First, a vaccine that shows little to no benefit over the control (placebo or not) is not an effective vaccine. Second, placebos aren't effective for everything. I highly doubt the effectiveness of a placebo at preventing HIV transmission (although it would be difficult to test ethically).
The placebo effect is important because it might _increase_ rate of HIV transmission by resulting in more risky behavior. Or, it might reduce rate of HIV transmission by causing the person to focus on the possibility of infection more.
Both vaccine and non-vaccine groups receive appropriate counselling (this part can be double blind even) regarding HIV, risk behaviors, and as a trial vaccine it might no be 100% effective etc etc... You assess the impact of behavior changes via surveys and interviews to see if there has been a significant increase in risk behavior and the control for it.
It would be unethical to give a placebo to someone for this kind of disease.
Until the treatment is proven - it may turn out to be the case that the placebo is more beneficial than the treatment.
If you knew that it would be "unethical to give a placebo to someone" then you wouldn't have to do the trial!
Indeed - there have been situations in which the Trial turns out to be so positive - that the study is canceled, and all participants are given the treatment. I think that was actually the situation with the circumcision trials - circumcision turned out to be so ludicrously low risk, and so effective at reducing HIV infections in heterosexual male populations in Africa, that they, ethically, had to prematurely end the study and circumcise all the participants.
They're placebo controlled. It would be a colossal waste of money to do it any other way. Besides being methodologically unsound, the trials wouldn't be recognized by the FDA or Health Canada.
The University of Rochester has also been working on HIV vaccines for many years. They're always recruiting subjects. The posters are interesting because you can see what stage this particular vaccine is at based on who they're looking for. If they're looking for married, middle-age straight non-injection-drug-users, it's safety trial. If they're looking for young single MSMs or injection drug users, then you know that vaccine has progressed to the efficacy trials.
The 'non-vaccinated' group he speaks of is the placebo group. The reason he mentions it 'head off' anyone assuming they would test it by exposing people to HIV.
There is no placebo group, it would be highly unethical to do so. Half the sample population gets the treatment half of it doesn't with the option to get the treatment once trial finishes. Changes in behavior due to treatment are accounted via survey pre-treatment and at measuring intervals.
You're mistaken: "Phase III would test the effectiveness of the vaccine in a larger group of about 6,000 volunteers who are at risk of becoming infected. Half would be given the vaccine and half given a placebo. Participants would then be tracked for three years to see how many in each group become infected." - http://www.ctv.ca/CTVNews/Health/20111220/canadian-hiv-vacci...
But more interestingly, why would it be "highly unethical" to do so? They're practicing informed consent, so everyone who gets a shot knows that there's only a 50% chance that they got the real vaccine. And they know that the vaccine isn't guaranteed to work (quite the opposite, in fact, based on the track record of similar trials here in the States).
"There is no placebo group" vs "Half the sample population gets the treatment half of it doesn't"
The "doesn't" is the placebo group.
And since every single other HIV vaccine has failed, it's likely that this one will also - so it's not like they are withholding an effective treatment and acting "highly unethical".
My impression this is going to be something other than a pure scientific experiment (and I don't mean that in a bad way).
Medicine and social sciences have a large body of research about things like the fact that you can't do a pure experiment with a control group if there's serious risks.
So I was going to ask how clinical trials for vaccines are done, and this part kind of answers it, but now I'm curious - if there's no control group that gets a placebo injection, how do you control for the fact that people may behave differently if they think they've been given an anti-HIV vaccine? Unless I'm misreading this and "non-vaccinated" means placebo.