Federal researchers on Thursday shut down the clinical trial of an HIV vaccine after it appeared that those given the experimental vaccine were slightly more likely to contract the deadly virus than those who got the placebo. Nearly 2,500 volunteers—all men or transgender men—have participated in the study of HVTN 505 vaccine since the trial began in 2009. Investigators insist that everyone who participated must be informed whether they received the vaccine or the placebo. Earlier trials had shown that the vaccine could produce an immune response when people came in contact with HIV, but the larger trial showed those who received it were actually at a higher risk to contract the virus.
SETBACK Conceptual view of HIV. (Science Faction, via Corbis)