HIV Vaccine Fails: Did Not Prevent Infection in Some

According to a recent study completed by the U.S. government, an experimental HIV vaccine has been halted because the vaccine did not prevent infection in some volunteers.

The study, called the "HVTN 505 clinical trial," kicked off in 2009 and had enrolled about 2,500 people in 19 cities. Participants were all men who have sex with men and transgender people who have sex with men. Half received an experimental vaccine developed by the National Institutes of Health, and half received dummy, or placebo, shots.

A safety review that was scheduled for Aprill 22 found that slightly more volunteers who had received the vaccine later became infected with HIV. Overall, 41 cases of HIV infection occurred in the volunteers who received the experimental vaccine and 30 cases of HIV infection occurred among the recipients who received the dummy injection.

The National Institute of Allergy and Infectious Diseases notes that the vaccine's failure is rather peculiar, nothing the increased risk of HIV among vaccine groups was not statistically significant when compared to the placebo group and the findings could be due to chance. 

However, the review also showed that the vaccine failed to reduce the amount of HIV in the blood, referred to as "viral load," in people who had been diagnosed with HIV and were tracked for 20 weeks of follow-up. 

The NIH said in a statement Thursday that it is stopping vaccinations, but will continue to study the volunteers' health, according to reports.