61–70 of 103 posts
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You don't. But given a large enough group of people, some will contract the infection "organically." So some people get a vaccine and some get a placebo and then you check back in years later and see if the vaccine group has a lower infection rate.
It says they used 30 people.
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I'm confused by the statement that a vaccine would not be a game changer in terms of worldwide infection. Right now, the only way to reliably prevent HIV infection is through changing behavior , which is extremely difficult. But widespread use of a vaccine would just require a one-time injection, which is relatively easier. I'm further confused by your polio reference, because that sort of effort would only be possib…
EDIT: I actually meant smallpox when I was talking about polio. That's a big error; corrected it above. Thanks rdl. I should have been more specific - I meant that if we did develop a vaccine, then it makes following the [smallpox] example theoretically possible, but this is still extremely challenging due to the reasons given. Although you and I might have the vaccine, not everyone has it - not by a long shot - beca…
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You don't need to get 100% vaccination to eliminate the disease; somewhere around 90% works, unless it's incredibly contagious and in a high density environment. "Herd immunity" protects the others -- basically, the disease itself can't spread if a sufficient number of people are vaccinated, so it dies out in a few generations (of the disease, not of humans).
From my classes in veterinary medicine, I believe the herd immunity is around the 80% mark, at least for livestock and their diseases.
The problem is the standard models of herd immunity depend on some simplifying assumptions which may be true in livestock, but are not true in humans -- specifically, that it's a homogenous population with equal chance of giving any other individual the disease, and that vaccines will be distributed fairly randomly as well.
If you have backwater villages which never get vaccinated, and are highly interconnected, you can end up with persistent reservoirs of disease, even if it's only 1% of your overall population. Then, you can have periodic epidemics when an individual from that area travels to an unvaccinated area elsewhere (because compliance rates on vaccination go down once the disease is "cured" in a population).
(I know about this from drinking with some of the UN/WHO vaccination people in Afghanistan)
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Actually, circumcision is a proven way to reduce infection rates that doesn't involve behavior. Though, as one might imagine, it can be a tough sell in cultures where that isn't the norm.
Just because infection rates are lower among males who are circumcised doesn't mean it prevents infection. http://en.wikipedia.org/wiki/Correlation_does_not_imply_caus...
Except there have been dozens of randomized, controlled studies that show circumcision significantly reduces risk of infection.
http://www.plosmedicine.org/article/info%3Adoi%2F10.1371%2Fj...
http://www.sciencedirect.com/science/article/pii/S0140673607...
http://www.sciencedaily.com/releases/2006/12/061213174708.ht...
http://journals.lww.com/aidsonline/Abstract/2000/10200/Male_...
My father is an infectious disease specialist who has spent the last 30 or so years working on HIV in research, patient treatment, and education. The following thought comes from my casual conversations with him, and probably does not represent his professional opinion. It certainly does not reflect his specific thoughts in regards to this trial, as we haven't yet discussed it. The progress in treating HIV since it f…
"those infected with HIV - who get treatment and adhere to that treatment - can live long and relatively normal lives." The adherence part is the most interest bit of the story. The adherence to HIV medications is ~93%, much greater than the adherence to almost every other drug or behavioral treatment. If diabetes patients or cardiac patients had adherence rates anywhere near that high then the life expectancy of the…
My father is an infectious disease specialist who has spent the last 30 or so years working on HIV in research, patient treatment, and education. The following thought comes from my casual conversations with him, and probably does not represent his professional opinion. It certainly does not reflect his specific thoughts in regards to this trial, as we haven't yet discussed it. The progress in treating HIV since it f…
Except the side effects (as with any drug therapy) can be severe. And the effects of long term use is anybody guess. Many patients who lived, just now reaching their 50's; are experiencing everything from diabetes to chronic kidney and liver disease to macula edema.
Course the trade off is death. So maybe it is a good deal.
1. Phase 1 is for safety 2. 30 is a small number
But the big issue here is the reason HIV and even the common cold is hard to treat -- high turnover and high rates of mutation.
So, even if you have Ab's and/or helper T cells (cell that remember an infection) against one or more strains of HIV, the presentation of the strain that an individual may pick up later on in life may be different and thus might not mount an immune response. Also of interest -- Helper T-cell sare the primary target of HIV.
In order to really determine if or not this vaccine is effective, we will have to observe the responses in people who have been given the vaccine and then contracted HIV later in life. While this is promising and will add another barrier against HIV, its unlikely to eradicate the virus.
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Shouldn't this be more of a temporary problem? As soon as there is a vaccine its patents will expire at least 20 years afterwards. And then lots of much cheaper vaccines will flood the market.
Patents aren't the problem here, but it's an interesting thought experiment to think about what commercial terms a vaccine for AIDS or other diseases which at this point mainly affect poor, third-world people would be distributed under. India would probably just violate the patent, claiming national security reasons, and sell it for ~production cost throughout the world. The USA might enforce a patent domestically, a…
I don't want to bum anyone out, but there have been quite a few potential vaccines that have made it through Phase 1 trials (several made it all the way to phase 3) only to be ultimately abandoned as ineffective or unsafe. Phase 1 is generally a small trial that is primarily designed to test the safety of the drug, not its efficacy.
I like hearing about scientific progress like this, but worry that it will be another "promising advancement" that we never hear about again, like a new cure for cancer or tax cuts for the middle class.
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"those infected with HIV - who get treatment and adhere to that treatment - can live long and relatively normal lives." The adherence part is the most interest bit of the story. The adherence to HIV medications is ~93%, much greater than the adherence to almost every other drug or behavioral treatment. If diabetes patients or cardiac patients had adherence rates anywhere near that high then the life expectancy of the…
Do you know why they reach +93%?
- expected or actual efficacy
- regimen complexity
- knowledge, commitment, and ability
- doctor-patient relationship
My understanding is that with HIV a lot of money has been spent on actually implementing the adherence research in order to reduce the spread of the disease, whereas for most other diseases no one really cares. I think getting diagnosed with HIV also encourages some people to grow up a little bit in a way that getting diagnosed with high blood pressure or whatever doesn't, though maybe less so now that infection vectors are changing.