BBC reports:
In the large-scale trial in Thailand, a combination of vaccines seemed to give volunteers a protective effect of 31%. The US military and Thai government, who co-sponsored the trial, said the effect was not caused by random chance but was statistically significant. But new data, being published at a conference in Paris on Tuesday, question that assertion.

But there were concerns as well. Researchers were not able to indicate just how the vaccines were working. And, as more data was given to scientists, the claims about statistical significance began to look increasingly shaky. Gus Cairns, who works with UK HIV information charity NAM, said: "This particular study was in the awkward position of producing a result that was only just statistically significant. "This means there was a one in 26 chance that the results could be due to pure chance - and that this may not reflect anything at all.

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