Evidence is building that an experimental AIDS vaccine given to 1,500 volunteers not only failed to protect those who received it, but may have put some of them at higher risk of contracting HIV than those who were given a placebo.At a Seattle meeting held Wednesday to discuss the latest findings, vaccine experts wrestled with the complex questions raised by the disappointing early results of the study, first disclosed by drugmaker Merck & Co. nearly seven weeks ago. Enrollment in the study was halted at the time, but researchers are still tracking the HIV status of the participants.
