Another AIDS vaccine bites the duist

A much-heralded H.I.V. vaccine has failed to work in a large clinical trial, dealing another serious setback to efforts to stop the AIDS epidemic. The vaccine’s developer, Merck, said yesterday that it had halted test vaccinations after the vaccine failed to prevent infection or reduce the severity of infection among volunteers who became infected during the trial. Hope for this elusive vaccine remains as about 30 other H.I.V. vaccines are being tested in people and all work somewhat differently, said Wayne C. Koff, a senior vice president of the International AIDS Vaccine Initiative in New York.