Monkey puzzles

As a growing number of vaccines move through the pipeline toward clinical trials, experiments with monkeys are producing puzzling data — and doubts.

The first full-scale trial of an AIDS vaccine is scheduled to end in November, and the world will soon learn whether it works. A second product will move into a large efficacy trial this fall. Earlier in the pipeline, the array of AIDS vaccines entering human studies is more diverse than ever before. “The pipeline is dramatically improved in many ways from five to six years ago,” says Peggy Johnston, who heads the AIDS vaccine program at the National Institute of Allergy and Infectious Diseases in Bethesda, Maryland. But, Johnston cautions, “significant scientific and operational challenges remain.”