An international team of researchers announced in September that for the first time, an AIDS vaccine has demonstrated some real ability to prevent HIV infections in a large clinical trial, reducing the odds of infection by about 31 percent.
The trial followed more than 16,000 people (who initially tested HIV-free) for three and a half years. They received either a combination of two potential vaccines or placebo shots. By the end, 74 placebo recipients had acquired HIV infections, compared with 51 vaccinated individuals. The trial report, published in October, included alternative analyses that put the vaccine’s effectiveness slightly lower, at around 26 percent, leading some to question the reliability of the results. The researchers reply that all of the analyses consistently support a modest protective effect.
AIDS researcher Jay Levy at the University of California at San Francisco finds the results encouraging, but notes that the vaccines seemed to have no effect on the amount of virus in the bloodstream of people who contracted HIV during the study. Nelson Michael of the U.S. Military HIV Research Program, which helped run the trial, is more optimistic: “We’ve shown that this 26-year global effort has not been in vain.”