After reading this story about possible vaccines. I started to wonder how do you test to see if it works? I mean, I may be wrong but I thought humans were the only species to contract HIV. Is this true? If so do they just inject volunteers and if it does not work, are those brave souls left with HIV? I know I’m missing something here…
They take a large number of volunteers, and inject half of them with placebos and the other half with real vaccines. And let them lead normal lives for several years. A few of them will get exosed to AIDS accidentally, and some of them get infected. If, say, 10 of the 1000 people who received placebos become infected and none of the 1000 in the vaccinated group, you can be fairly sure that the vaccine worked. And those unfortunate 10 people would probably have contracted AIDS anyway if they hadn’t volunteered to be part of the study.
How will you distinguish between those that have been exposed to the real virus versus those that have been exposed to the vaccine? Most screening seems to use an antibody test, wouldn’t you be antibody positive if you’ve had the AIDS vaccine?
You can test for the virus particles themselves, although it is more time consuming than testing for anti-bodies. You can also give the vaccine to people who are already HIV positive and track the development of viral load over time, and compare it to those who received similar treatment regimes. You can statistically compare the etiological history of populations with the vaccine, and those without, and judge the strength of the immune response from the vaccinated population, in comparison to the unvaccinated population.
A vaccine is not a magic bullet. Eventually it comes down to your body, vs the virus. Clinical trials will eventually have to include populations of identified uninfected people, and compare the infection rates in double blind groups who receive placebo vaccinations, and the real vaccine. That doesn’t mean you have to deliberately infect anyone. You just have to wait a long time to get a final clinical trial. You can do a lot of biochemistry studies among the currently infected population, and you can get some pretty good information studying high risk populations, if you can get cooperation.
Newly infected patients can benefit from effective vaccine actions, and in some cases that can be a very effective gauge of how well your vaccine will work on uninfected populations. If you have enough of that sort of trial to be sure of the safety of your vaccine, you may be able to get a very large at risk population, say one of those countries where infection rates are already in double digits, to accept inoculation in large numbers. Ten years later, you see if the infection rates show a decline. If it does, you duplicate your test group over an even larger population, perhaps including lower risk groups.
Tris
-
The simian version SIV is extremely close to HIV. So you can develop vaccine methods for chimps. Once you got that all worked out, then you know you might have something worthwhile. This is pretty much where the most respectable research is.
-
The antibody in the vaccine may not be the same one used in the HIV test. Viruses have lots of different surface components that can generate different antibodies. HIV, in particular, is notorious in this regard. (But so is the common cold.) So a vaccinated person could easily pass a suitable antibody-based HIV test.
-
Prisons. Classic pool of medical test subjects. Even “better” is that acquiring HIV in prison is extremely common. Makes it easier to notice an impact. I also suspect that if you advertise “free HIV vaccine trial” in the local gay newspaper, you will have a ton of volunteers.
The real issue is convincing people: “You might have been given a placebo or a vaccine that turns out not to work. Please continue safe sex.”
I was actually wondering about this myself, as I saw a flyer posted for an HIV vaccine study needing volunteers at my university. Most medical studies needing volunteers loudly display the amount of compensation (if any), but at the bottom of the HIV flyer it said in little teentsy letters compensation provided .
What I am curious about is what happens if the trial vaccine causes you to develop HIV? I’ve participated in a couple studies, but you would be hard put to convince me to get anywhere near that one.
Peace,
~mixie
Well, I was confused by the question " How do you test for a AIDS vaccine?"
I thought that meant you test someone to see if they have been vaccinated?
What scientists needed was a way to check if there was any live virus particles in their
vaccine before they injected it. Once they were confident on that they could do some human tests. That’s
my take on this, but its pretty common.
Before the vaccine is tested on actual people, it would be tested in tissue cultures, wouldn’t it?
I don’t think there is any way of testing AIDS in tissue culture, but I could be wrong.
Basically the first anwer was right. A large group of volunteers would be told that half of them would get the vaccine and half not. They would also (I have read this and I do believe it) be strongly counseled to use condoms, sterile needles, etc. In other words they would be treated the way everyone ought to be in terms of avoiding AIDS. It is nonetheless predictable that at least some will be exposed and at least some of the unvaccinated group will be infected. If none, or very few, of the vaccinated group get HIV, then the trials will be terminated and the remainder vaccinated. Then vaccine will be prepared for all.
If, on the other hand, the vaccinated group is infected at the same rate as the control group, then the trial will be abandoned. From what I have heard, it is likely that the early vaccines will not test at either of those extremes, but rather they will find a somewhat lower rate of infection among the vaccinated than among the control. They will probably use the vaccine because even lowering the rate could eventually end the pandemic. If you could get the average number of people infected by an infected person below 1, the infection will eventually peter out. Like a sub-critical mass of U-235.
Here is a paper on this, it’s great reading & not too much tech language:
http://www.fest.org.za/docs/archimedes/3637.pdf
Quoth MixieArmadillo:
Then you get HIV. That’s a risk that you agreed to when you signed up for the trial. Many folks have the mistaken and dangerous idea that “experimental medical treatment” means that someone has a miracle cure, but doesn’t want everyone to have it. What it really means is that nobody knows yet whether the treatment works, and it might be worse than nothing.
You say that you’d be afraid of the risks, for an AIDS vaccine trial, and that’s entirely your decision to make. It’s good to see that you realize that it is a decision you need to make.
I shall file that under “duh.” What I meant was, I wonder if the study offers some sort of compensatory medical care or treatment for those who are infected or suffer adverse side effects as a direct result of participating in the study. Involving human subjects seems to imply that either a) they are fairly certain the risk of infection from the vaccine is very low, b) they are willing to be stand up guys and provide for you in the event that their little experiment gives you a godawful, terminal, body-rotting illness, or c) they have a very very extensive and legally air-tight waiver saying “I the undersigned am going to go ahead and let you inject me with some sort of HIV-related fluid. I don’t mind that it could cause me to spend the rest of my truncated life in pain and misery as my body disintegrates, in fact, I’m happy to fling my existence to the wind. Shoot me up.” Any of these seem like clear possibilities, but I find it difficult to believe that the researchers would have gotten permission to do a study on human subjects that puts them in the direct line of death, and I assume they’ve made some provisions for the possibility somewhere–whether it be offering medical care or saying “you’re on your own, bucko. sign here.”
peace,
~mixie
The HIV Vaccine test at the University of Rochester is conducted in the way described above, with strong counseling for participants on how to NOT get HIV. Some people will behave in ways that make them likely to contract it, anyway. The infection rates are compared to the rates of the general population controlled for race, sexual orientation, age, economic class and other factors. The vaccine itself cannot, as far as anyone knows (and ther have been countless tests) infect the recipient with HIV.
odviously you do it in africa. or some country where its an insaine pandemic. find all the guys that have sex with prostitutes every night… give it to them… if they stop getting AIDS… your on to something… otherwise… they woulda gotten it anyway
That method would be completely unethical. There was actually a good deal of resistance from the African-Amercian community (one of the higher risk groups) to participating in the trials because of the “Tuskeegee experience.”