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» Hatrack River Forum » Active Forums » Books, Films, Food and Culture » AIDS Vaccine - Great Breakthrough

   
Author Topic: AIDS Vaccine - Great Breakthrough
Phanto
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AIDs Vaccine shows some efficacy.

First step on a long process to fight the disease.

[ September 25, 2009, 12:51 PM: Message edited by: Phanto ]

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BlackBlade
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Saw this this morning. 31% is nothing to sneeze at that's for sure.
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Miro
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!
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Shmuel
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A more skeptical take.
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The Rabbit
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I saw this and have some serious doubts about whether these results are statistically significant.

I also think there is very legitimate concern over using a vaccine that is only a 31% improvement over nothing when we already have much more effective means of controlling the spread of HIV. A relatively ineffective vaccine like these could actually increase the spread of HIV if people who get the vaccine then engage in riskier behaviors.


P.S. Edited to add that I posted this before I read the link Schmuel posted. The information in that link reinforces my original skepticism. I would be much more excited about a 31% effective vaccine against malaria or TB. But things are different with AIDS specifically because peoples individual choices are so important in the spread of the disease. A marginally effective AIDS vaccine may in fact be worse than no vaccine at all.

[ September 27, 2009, 06:19 PM: Message edited by: The Rabbit ]

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DDDaysh
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I agree with you Rabbit, if we're talking about developed nations. However, if we could immunize all the women in Africa or India who often have little to no choice about their sexual partners, it may be useful.

Of course, we can't even get many people in other nations to accept a vaccine against Polio, so I'm not sure how realistic that hope is.

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HollowEarth
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You really think that? A vaccine that's only 31% effective sounds like a good way to spread false hope to me. And give people an excuse to avoid any safe(r) sex practices they may have been convinced to adopt.
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The Rabbit
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quote:
Of course, we can't even get many people in other nations to accept a vaccine against Polio, so I'm not sure how realistic that hope is.
I don't think the problem is people refusing to accept vaccines. It is a problem of vaccines being unavailable at a price people can afford. And if you look at Schmuel's link, that problem will be raised to 6th power for this AIDS vaccine. There is no way these could be used in the parts of Africa and India you are talking about.

And even in those parts of the world, people aren't nearly so helpless to control their sex lives as you suggest. The ABC program has been much more effective in Africa than this vaccine.

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Lyrhawn
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quote:
The ABC program has been much more effective in Africa than this vaccine.
That's an odd claim isn't it? This vaccine had its trials in Thailand didn't it? That would mean that, even though it's not a commercially approved vaccine, which would mean it's not in widespread use anywhere, it's probably never been used in Africa at all. If I flew to Africa and educated a single person about condom use, I would be "much more effective" in Africa than this vaccine.

I mention that only because your statement seems to suggest that the ABC program has been quite successful, when much of what I've read (though admittedly, I haven't read anything in the last year or two on it), has led me to believe that the results are highly mixed depending on which country you look at. I don't see any sort of concrete across the board success.

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fugu13
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You're misinterpreting the statement. Rabbit means that if you compare the results of the ABC program in Africa with the results of this vaccine in Thailand, the ABC program has been much more successful at reducing AIDS spread. I make no comment as to the accuracy of that statement.

More pertinently, as the linked article alludes to, various programs in Thailand have already created much larger drops in infection there than this vaccine appears to.

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The Rabbit
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fugu is right Lyrhawn, you misunderstood my point. If you look at the countries where the ABC program has been most successfully implemented, the reduction in the spread of AIDS has declined by about 70%. That is more than twice as effective as this vaccine was in the Thailand study. Furthermore, the effectiveness of the ABC program in say Uganda is calculated based on the entire population of the country and not just control groups who are fully participating in the program, which makes its success all the more impressive.

So even if the results of this study are statistically significant (which I think is seriously in question) and we could vaccinate every person in Uganda six times over a several year period, the incidence of AIDS in Uganda would more than double if people returned to their pre ABC sexual behavior.

And while I realize that ABC hasn't been as successful in all regions, that is most likely because it isn't being taught as effectively not because it or similar educational approaches can't work. Vaccines have to be effectively implemented too. In countries without a decent medical networks, that can't even properly distribute vaccines that already exist and have proven effective, the barriers to effect use of a vaccine are every bit as great as the barriers to teaching people to engage in safe sex. Probably greater.

Look at Thailand. In Thailand the number of new HIV infections dropped from 143,000 in 1991 to 19,000 in 2003 -- thats an 87% decrease across the entire population. That decrease was not the result of any medical advances, it was solely the result of aggressive education about the spread of the disease and how to prevent it. And that decrease wasn't just in a controlled study looking only at people who participated fully in the program, it was for the entire country. My guess is that if you looked at only a control group who had been part of the full educational initiative, that percent would be even higher.

In this context, an AIDS vaccine that is less than 99.99% effective presents not progress but a serious threat to control of the spread of this disease. I'm not saying we shouldn't be working on a vaccine. What I'm saying is that we have right now all the technology we need to stop the spread of AIDS. Any vaccine that is developed needs to be compared with the existing technologies and existing plans to implement them recognizing fully how a vaccine will affect human behavior.

Right now, abstinence, monogamy and consistent condom use are far more effective than the most positive spin you can put on this vaccine.

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Tresopax
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I don't think this is a great breakthrough because we now have a vaccine that is 31% effective. This is a great breakthrough because it suggests we may be a step closer to a vaccine that is highly effective.
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The Rabbit
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quote:
Originally posted by Tresopax:
I don't think this is a great breakthrough because we now have a vaccine that is 31% effective. This is a great breakthrough because it suggests we may be a step closer to a vaccine that is highly effective.

I would agree with that if I thought this was truly a step closer to a vaccine that is effective. There are plenty of reasons to be skeptical of this study. The small margin that was observed between the control group and the vaccine group in this study is very likely to be a statistical anomaly. Something as simple as two burst condoms could explain the difference between the two groups. That makes me even more concerned that the media has put an overly optimistic spin on these results which in turn raises very serious concerns about how this will influence peoples behavior.
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Shmuel
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A followup.
quote:
The full results from an AIDS vaccine trial in Thailand, released Tuesday, showed that the vaccine’s protective effect might be even weaker than researchers first admitted.
Also, from a link therein, the full published results.
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The Rabbit
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Just like I said a month ago.

This study was always on the knife edge of 5% statistical significance. In other words, there has always been at best a 1 in 20 chance that the 31% effectiveness was nothing but a statistical anomaly. No it looks even higher than the original 1 in 20.

I'm not a betting woman and I almost always side with the odds, but given that scientist don't have any explanation for why two vaccines that didn't work alone would work when administered together, my moneys on the statistical anomaly.

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fugu13
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That's not a correct characterization of what statistical significance means. Statistical significance is the probability that an event would be observed if the null hypothesis were true. So 5% statistical significance means that, if there is no effect from the vaccine (what I presume the chosen null hypothesis was), we would see such results 5% of the time.

It does not say at all that there is a 5% chance the effectiveness was nothing but a statistical anomaly. This is understandable, as whether or not there is an effect is an absolute fact -- it has no probability associated with it. The only question is whether we detected an effect. Of course, 5% statistical significance does not mean there is a 95% chance we detected a real effect, either.

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