The world’s first attempted Aids vaccine proved a failure yesterday when, after four years’ work, the Californian biotech company VaxGen announced that trial results showed that it did not protect those at risk of HIV infection.

VaxGen did its best to put an optimistic spin on the collapse of its hopes of selling the vaccine to the US and Europe by offering the surprising finding that its AidsVax had appeared to protect African Americans and, to a lesser extent, people from some other ethnic groups.

But the 78% efficacy in black volunteers, although statistically significant, proved to be based on just 13 cases of HIV infection.

The statistical problem in proving significant effectiveness against a low-incidence condition are far greater, and require much larger numbers of subjects, than against higher-frequency conditions. It is very likely that the finding that the vaccine worked in minority populations was a statistical fluke, although the company appears to be whoring with it.

Seth Berkley, president of the International Aids Vaccine Initiative (IAVI), said: “It is difficult to draw conclusions about what this means.”

John Moore, a professor of microbiology at Cornell University in New York, said: “The common sense is that this is a very small group of patients and I think they are data dredging.”

VaxGen said it intended to seek a licence to market the vaccine to those groups – African Americans and other (North American) ethnic minorities, excluding Hispanics – in whom efficacy had been shown.

“This is the first time we have specific numbers to suggest that a vaccine has prevented HIV infection in humans,” said Phillip Berman, its senior vice president for research and development and inventor of the vaccine. Guardian/UK