
For First Time, AIDS Vaccine Shows Some Success in Trials - timr
http://www.nytimes.com/2009/09/25/health/research/25aids.html?_r=1&hp
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redcap
Some success: 30% effectiveness in that 51 out of 8000 given the vaccine
because HIV positive, and 74/8000 given the placebo did. I presume that really
is statistically significant despite the chance it could have just been
random?

They also don't know how it works...

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timr
_"Although the difference was small, Dr. Kim said it was statistically
significant and meant the vaccine was 31.2 percent effective."_

The confidence interval is determined by the number of people in the trial
(N=16,400), not the number of people who get sick.

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sambrightman
If the rate of infection in the general population was even lower, say 1 in
100,000, and they actually trialled 200,000 people, finding that the vaccine
perfectly prevented infection, should they conclude this with high confidence?
Or have I misunderstood you?

Besides, Dr Kim is quoted elsewhere as saying "the result could be due to
chance" and the vaguely phrased "31.2 percent effective" is not encouraging.
Add in the likely funding source of AIDS vaccine trials, the pressure to get
results and the unknown mechanism and it doesn't look so great.

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psyklic
The key is not to find "who gets HIV" vs. "who does not get HIV." Instead, we
are trying to measure "who gets exposed" vs. "who gets HIV." Although we do
not know how many people are _exposed_ in each group, we can make sure that
the number of exposed people in each group is approximately the same by
increasing the number of people vaccinated. If we know that the same number of
people are exposed (which is less than the sample size), then the number of
people who get sick is much more significant.

By increasing the number of vaccinated people, the number of exposed people
becomes more equal between the two groups since a few "more exposed/risky
people were assigned to group A" will have a less significant impact.

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th0ma5
link from the AP feed
[http://hosted.ap.org/dynamic/stories/M/MED_AIDS_VACCINE?SITE...](http://hosted.ap.org/dynamic/stories/M/MED_AIDS_VACCINE?SITE=INKEN&SECTION=HOME&TEMPLATE=DEFAULT)

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onreact-com
So the US army is using Thai people as guinea pigs?

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earl
They probably sought them out for their high incidence of HIV -- it would
obviously be unethical to specifically infect people to test the vaccine.

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scott_s
To add to this, at the time the trial started, Thailand was one of areas with
the highest infection rate. It's common practice to do a trial where the
disease is the worst.

