For First Time, AIDS Vaccine Shows Some Success in Trials

http://www.nytimes.com/2009/09/25/health/research/25aids.html?_r=1&hp

by timr • 17 years ago

26 14 17 years ago

th0ma5• 17 years ago

link from the AP feed http://hosted.ap.org/dynamic/stories/M/MED_AIDS_VACCINE?SITE...

redcap• 17 years ago

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...

timr2• 17 years ago

"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.

sambrightman• 17 years ago

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.

cgherb911• 17 years ago

I have to agree that the numbers don't seem to differ significantly enough to draw any conclusive evidence. I agree with your math in saying that if you had the vaccine, your chance of infection is .6375% and without the chance of infection is .925%. From this perspective I don't see any hard numbers to back the claim. I'll wait for a more better controlled experiment before I believe this one.

earl3• 17 years ago

I presume that the investigators used something like the t-test for a difference of means. You treat 1/2 the group and don't treat the other; if you selected these two groups randomly, then they should a priori have equal likelihood of infection. You then can create a confidence interval for the hypothesis: are the two means / rates different.

See the second use here: http://en.wikipedia.org/wiki/Student%27s_t-test

tokenadult2• 17 years ago

http://healthpolicy.stanford.edu/news/even_modestly_effectiv...

onreact-com• 17 years ago

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

earl3• 17 years ago

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

scott_s• 17 years ago

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.

tokenadult2• 17 years ago

The article reports that the Thai government (the Thai Ministry of Health) has cooperated willingly with this study. Thailand was an early country in Asia to have a high AIDS infection rate, and has been a leader in that part of the world in working on strategies to find community approaches to preventing the spread of AIDS and to find medical preventives and cures for AIDS.

For First Time, AIDS Vaccine Shows Some Success in Trials

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