"The National Institutes of Health on Thursday halted a study testing an experimental HIV vaccine after an independent review board found the vaccine did not prevent HIV infection and did not reduce the amount of HIV in the blood," Reuters reports (Steenhuysen, 4/25). "The trial, known as HVTN 505, started in 2009 with 2,504 gay male volunteers in 19 cities who got three shots over eight weeks," the New York Times notes (McNeil, 4/26). According to a statement from the NIH, the data and safety monitoring board that reviewed the study to date said "there was a non-statistically significant increase in HIV acquisition among volunteers in the investigational vaccine group compared to those in the placebo group. It is not clear why this occurred and further analysis is needed to draw any firm conclusions" (4/25). The agency said it "is stopping vaccinations in the study, ... but that researchers will continue to study the volunteers' health," the Associated Press reports (Neergaard, 4/25). "Numerous HIV vaccine efforts, including one with a similar approach to the current trial, have failed to show a benefit," but "[r]esearchers continue to hunt for an immunization that can prevent infection," Bloomberg writes (Cortez, 4/25).