How do HIV Vaccine Trials Work?

Question

Occasionally I see ads for participants in HIV Vaccine trials. I wonder, what does this entail for the person?

Because, it'd seem in order to test a vaccine, someone must be exposed to the virus after inoculation. Otherwise, how would anyone know the vaccine's effectiveness.

SO, are trial participants expected to receive the vaccine and knowingly participate in unprotected sex, to see whether or not they contract HIV? And if so, who would participate in something like that?

Answer 1

That's not quite how it works.

A vaccine trial usually uses a "randomized double-blinded cohort study" format. Let me define that piece by piece.

In a randomized trial, subjects are randomly assigned either the vaccine or placebo. This is done by random-number generator. The two groups should be divided pretty evenly and should not be biased for a particular trait or risk factor (i.e., one group is all female, or one group has a lot more gay men than the other, etc.).

In a double-blind trial, subjects don't know whether they've been given the vaccine, or a placebo. Not only that, but the clinicial giving the injection also doesn't know what's in the syringe. Only a few small number of researchers know who got what.

A cohort study is a study that compares two groups of people based on an exposure. They follow the groups over a period of time and measure their outcomes. In this case, the exposure is the vaccine. They give the test subjects either the vaccine or placebo, check up on them periodically for health status and HIV status, and at the end of the study period (years for vaccines) they count how many people acquired HIV.

In the meantime, the subjects live their lives, have sex as they normally have sex, do whatever drugs they usually do, and so forth. This means maybe the test subjects are celibate. That's fine. Maybe they don't do drugs. That's fine, too.

The reserachers will sort this out at the end. They will interview the subjects for their health habits. Did they have sex with or without condoms? How many partners did they have? Did they have knowingly have sex with any with HIV? Did they use drugs? Did they get any blood transfusion or organ transplants? And so forth.

Then the researchers run their analysis, run a lot of statistics and then maybe they'll have a significant finding.

Answer 2

Vaccines may be examined on animals however the appropriate product is extensively utilized for the income of animals, not basically human beings. Animals get vaccinated for lots of the comparable ailments we do (and others). for this reason, the lives animals and human beings could be saved in basic terms from one little shot. And any extracted serum protein of regardless of animal could be taken on an identical time as this is alive and happy. this is in basic terms like giving blood to the crimson go. i wish no person is heartless adequate to disclaim this lifesaving gadget to harmless infants and animals in basic terms as a results of fact they don't choose animals to be examined on. not that i individually think of any regulation maker may be loopy adequate to purchase that sob tale and illegalize vaccinations. regardless of the reality which you in no way can tell. And it says excellent on the lable what the climate are. no person's masking something up.

Answer 3

They don't inject the virus into you. Depending on the trial, it might a portion of DNA from the virus, or a specific protein. Volunteers go in, their blood is drawn, and studied in a lab. There is no risk of catching the actual virus from the injection.

Answer 4

Toxicology has traditionally focused on ADMET studies:

How the drug is Absorbed into the body.
How it is Distributed to the tissues.
How the body Metabolizes it.
How the body Eliminates it.
And the Toxic effects.

Toxicity is determined mostly by how the chemical is metabolized by the body. Many different genes influence how a drug is metabolized. James P Kehrer PhD, of the Division of Pharmacology and Toxicology at the University of Texas at Austin stated, “Small differences in gene structure can make large differences in function.”[i]

Drugs are theoretically supposed to hone in on a specific single target/molecule and leave all other targets alone. The problem is that this is often more true in theory than in practice. (6.7% of hospitalized patients suffer severe adverse drug reactions.[ii] Serious being defined as an event that prolongs hospitalization or results in death or disability.)

William Bains, chief scientific officer of Amedis Pharmaceuticals in the UK estimates that 50% of all drugs in development fail to progress to the market because of problems associated with ADMET, and 50% of all drugs that do make it to market have problems associated with ADMET.[iii]
80% of new chemical entities (NCEs) fail after Phase I clinical trials. Hepatotoxicity (liver damage) is the most common reason for the failure. Barry Selick, formerly with Glaxo Wellcome and now with Camitro, a company specializing in ADMET believes that for every drug that is withdrawn from the market, 10 remain available to people even though they have ADMET-associated problems. He also says that for every drug that is on the market with ADMET-associated problems, there is an additional 10-50 that will fail before they reach the general public.[iv]

When a drug enters clinical trials, the company has very little idea if it will damage humans. Because ADMET studies in animals are so unreliable, Tom Patterson, chief scientific officer at Entelos, likens the current practice of drug testing in humans during clinical trials to making airplanes, trying to fly them, and marketing the one that does not crash.[v]

Mark Levin PhD and CEO of Millennium Pharmaceuticals, presented data on this at an August 2001 Drug Discovery technology conference in Boston. In a study conducted at a major drug testing company, 28 potential drugs were tested in rats. 11 showed liver toxicity in the rats while 17 did not. Of the 11 that were thought to be hepatotoxic, 2 were shown to toxic in humans but 6 were shown to be safe for humans
Of the 17 that tested safe in the rats, 8 were also safe in humans but 6 went on to be toxic to the liver. Levin concluded that this means the rat data was basically as accurate as a coin toss.
This is why many new medications fail in humans.

Clearly, the ADMET testing process is inadequate.
What is needed in ADMET studies is pharmcogenomics. By classifying patient populations based on their response to drugs and based on the drug metabolizing enzymes (DMEs) they have, drugs can be prescribed in a safer more effective fashion.

Patients who have the gene or protein that causes the adverse side effect can be given a different drug and patients who metabolize the drug slower or faster can have their dosage schedule altered accordingly.

Clearly this is the most ethical way to develop new drugs. Additionally, data can be used from in vitro studies, computers, epidemiology, analysis of the chemical structure and chemical properties of the candidate drug all of which predict toxicity much better than animal models.

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[i] American Chemical Society Short Course. The Role of Toxicology in Drug Discovery. August 16, 2001Boston, MA.
[ii] JAMA 1998;279:1200-05
[iii] Nature Biotechnology 2001;19:722-26
[iv] Nature Biotechnology 2001;19:722-26
[v] Nature Biotechnology 2001;19:722-26

Answer 5

I don't realy know this. You may ask the question at the HIV comunity: http://www.positivesingles.com/blog/monemagic