The National Institute of Allergy and Infectious Diseases announced Thursday the cancellation of a large-scale HIV vaccine study that started in 2009 after the experimental HVTN 505 vaccine showed no signs of protecting against the virus that causes AIDS.
A review of the study this week determined that HVTN 505 vaccine recipients were more likely to become infected with HIV than participants who were given a placebo.
Of the 2,504 volunteers in the study, 1,244 were given a placebo and 1,250 were provided the experimental vaccine. Overall, 41 people given the experimental vaccine were infected with HIV, compared to 30 placebo recipients.
When the findings were refined to only include the number who became infected 28 weeks after receiving the experimental vaccine or the placebo – a timeframe chosen to allow the vaccine to "stimulate an immune response" – 27 experimental vaccine recipients were infected with HIV, as were 21 placebo recipients.
The NIAID described the increased incidence of HIV infections in the experimental vaccine group as "non-statistically significant" in its Thursday statement.
"It is not clear why this occurred and further analysis is needed to draw any firm conclusions," the federal health agency said. "Based on the finding, the [independent data and safety monitoring board] recommended closer follow-up of participants beyond their month 24 study visit. NIAID concurred, and will, in concert with the study investigators, be amending the study protocol to allow for closer, extended follow up of the vaccine recipients."
The cancelled study solicited men who have sex with men and transexual participants.
Since the 1980s, when HIV/AIDS emerged as a global pandemic, life expectancy has gone from drastically shortened to near-normal with treatment. The increase is largely attributed to anti-retroviral therapy treatments developed in the 1990s. A 2012 analysis by researchers at University College London projected a median life expectancy of 75 for men who receive treatment after being diagnosed with HIV at 30, a seven-year decrease from normal life expectancy.
German doctors confirmed in 2010 the first known "cure" of an HIV infection, in a man who received a bone marrow transplant as treatment for leukemia. In 2012 the U.S. Food and Drug Administration approved the drug Truvada for people at-risk for HIV after a National Institutes of Health-sponsored study found it decreased the chances of contracting the virus by 42 percent.