Truth About That "AIDS Vaccine Breakthrough"

The New York Times and online news outlets like WebMD and DailyKos are starting to analyze more carefully the more sensationalist claims of an "AIDS vaccine breakthrough" that you may have heard pf last week.

For example, Times reporter Donald McNeil reports that

In the data itself, the real margin of success was razor-thin: 23 Thais out of 16,395.

That is, three years after getting the vaccine or a placebo, 74 in the placebo arm of the trial became infected while only 51 in the vaccine arm did.

Bloggers with a taste for biostatistics — and one rival AIDS vaccine specialist who declined to be quoted — said it would take only a handful more infected Thais in the vaccine column to shift the results from “statistically significant” to meaningless. Even one more would have weakened the data enough to make headlines saying “One Quarter Protected” more likely, given the way journalists round off numbers.

Got that? The 1/3rd protect meme that was propagated last week came from the fact that 23 fewer Thais out of more than 16,000 participants who would have been expected to get HIV, did not.