September 19, 2011
About 850 researchers and others gathered to discuss clinical trial updates and scientific advances in HIV/AIDS vaccine development at the four-day AIDS Vaccine 2011 conference, which concluded Thursday in Bangkok.
"It's not just good science, but to be in the country where the largest AIDS vaccine trial in the world took place -- and the first trial to demonstrate that a vaccine was possible -- it's pretty exciting timing," said Mitchell Warren, head of the nonprofit AIDS Vaccine Advocacy Coalition.
The first-ever evidence that an HIV/AIDS vaccine candidate was even partially effective involved a 2009 Thailand trial with 16,000 participants. The experimental RV-144 vaccine had a protection rate of about 31 percent.
"Over the last two years, an unprecedented international collaboration has been underway to try to understand why we got the modest effect in that trial that we did," Warren said. Scientists have theories about what led to RV-144's efficacy, he said. "It is what we call hypothesis-generating, and there is going to need to be some additional studies to confirm that. But these are the first signals we've ever had," he said.
A follow-up trial to RV-144, reflecting post-2009 data and developments, is expected in 2014.
In about 20 US cities, the world's largest ongoing HIV vaccine clinical trial will involve 2,200 participants and continues to recruit volunteers. The HIV Vaccine Trials Network 505 (HVTN 505) study is exploring a combination of two experimental vaccines and will focus on transgender women and men who have sex with men.
"These are complexities and challenges that we've longed for," said Warren. "I think it's safe to say that vaccine trials are going to get more complicated, but more interesting in the next couple of years."
Boston is hosting the AIDS Vaccine 2012 conference.