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October 20th, 2009

Well That Was Fast! HIV Vaccine Trial Published

canaryRemember the HIV vaccine trial press release?  The one announcing the first-ever positive result?

Then the backlash, with people questioning how the analyses were done, and reported?

Now, less than a month later, we have the scientific presentation and the paper appear on the same day.

Read all about it here and here.

If you want the view from 10,000 feet (why is that the chosen altitude for that cliche?), here it is:

  • The vaccine strategy combines two vaccine generally thought to be ineffective on their own — canarypox ALVAC-HIV and glycoprotein 120 AIDSVAX B/E — in a “prime and boost” approach
  • Over 16,000 patients are enrolled in Thailand in a placebo-controlled trial
  • The “modified intention-to-treat” analysis, which excludes those who are found to be HIV positive at entry, shows a modest but statistically significant protective effect, reducing the infection rate by about 30%
  • There is a trend towards a protective effect in the intention-to-treat and per protocol analyses
  • In those who were vaccinated and became infected, there was no effect on CD4 cell count or HIV RNA

Numerous questions remain, many of them summarized in this accompanying editorial:  Why did it work when the individual strategies didn’t?  How durable is the protection?  How do the strains causing infection relate to those in the vaccine?  Did the per-protocol analysis fail to show a significant protective effect solely because of a smaller sample size?  Would the vaccine work if tested on higher-risk populations?  What effect will this study have on the ongoing vaccine development effort, both in the lab and in trials?

Answers to some of these questions may be forthcoming.  Regardless, the surprising results of this study serve as a reminder of just how mysterious the immune system remains — despite some incredibly smart people working on it with lots of resources.

Because if you asked the vaccine cognoscenti to vote a little over a year ago on which strategy in clinical trials would end up with a positive result — the “prime and boost” one published today or the adenovirus vector approach –  the latter would have won in a landslide.

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HIV Information: Author Paul Sax, M.D.

Paul E. Sax, MD

Editor-in-Chief

NEJM Journal Watch HIV/Aids Clinical Care

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