Thai AIDS vaccine trial: Risk of HIV infection can be reduced with a vaccine

May 18 2010

For more than a decade, researchers and advocates have marked HIV Vaccine Awareness Day with varying degrees of hope, cynicism and despair. This year, in large part because of the results of the Thai Prime-Boost vaccine study, there is greater cause for hope than ever before and a renewed sense of urgency to transform this hope into a reality.

In September 2009, the world's largest AIDS vaccine trial to date showed the first evidence that an experimental AIDS vaccine could lower the risk of HIV infection. The results were complex; the observed benefit from the vaccine was modest; and the field is still years away from a highly protective vaccine.

"The caveats to the Thai Prime-Boost study results are important and true. But letting them become the entire story does a severe, even dangerous, disservice to the field, the trial and especially the 16,000 people who participated in the trial," said Mitchell Warren, Executive Director of AVAC: Global Advocacy for HIV Prevention. "Despite the many perspectives on and interpretations of the trial – and its results – the Thai AIDS vaccine trial provides evidence for the first time that it is possible to reduce the risk of HIV infection with a vaccine. AVAC and others have worked to explain the uncertainty of the results and the need for follow-up research. We will continue to do this because the science is complicated, and the future is unknown."

But for HIV Vaccine Awareness Day, AVAC's loud and clear message is that the Thai Prime-Boost trial changed the game for AIDS vaccines. A preventive AIDS vaccine is possible. The results were surprising to many and prompted some skepticism. But it is potentially disastrous if all that advocates, potential donors and future HIV vaccine trial volunteers and researchers think about the trial is that it gave a murky result, that it failed or that it left us no closer to an AIDS vaccine than we had been before.

"In fact, there's renewed energy in the AIDS vaccine field today, even as we grapple with what these results mean and where we go from here," said Warren. "The next steps for the field must involve more not less: more trials, more community volunteerism, more political will and sustained funding. One way to help ensure this is to celebrate what's happened to date, even as we prepare for everything that still needs to be done."  

AVAC proposes three key steps for the AIDS vaccine field.

• Work aggressively to see what information can be gleaned from further analysis of the biological samples from more than 16,000 Thai men and women who participated in the trial and hope that we might learn why this vaccine combination worked at all.
• Build on this result, testing similar vaccines and combinations in different populations.
• Ensure that there is an increasingly diverse scientific portfolio to develop and test entirely different approaches.

There is no question that more resources are needed for existing AIDS treatment and prevention programs. People living with HIV deserve treatment and care, not waiting lists and death. But people who are at risk of HIV infection also deserve new ways to protect themselves.

Fully funding HIV treatment and prevention programs and HIV research would require only a fraction of the trillions of dollars governments have spent on bailing out big companies, and it would be a wise investment for the long-term economic stability of families, communities and nations.

"It's easy to call for all of these things, but it is much, much harder to achieve them," said Warren. "We hope that the next chapter of AIDS vaccine research shows the field capable of greater efficiency and prioritization: triaging current projects, jettisoning some, cutting costs within others, scaling up still others, and developing a clear strategy for collaborative action on key goals. We need a fully funded comprehensive approach to AIDS prevention and treatment, which includes finding new HIV prevention options, such as AIDS vaccines and antiretroviral-based HIV prevention, including pre-exposure prophylaxis (PrEP) and microbicide gels that could be used by women and men to protect themselves from HIV infection."  

The Thai Way Forward: A New Report from the Ground

To mark this HIV Vaccine Awareness Day, AVAC is launching The Thai Way Forward, which tells the story of the world's largest AIDS vaccine trial using the voices of the people on the ground who made the trial happen.

"Every clinical trial, especially a large HIV prevention efficacy trial, is a complex story with fascinating characters, complex science and many perspectives. Success depends on a combination of coordination, communication, urgency and patience," said Warren. "With this report, we wanted to delve into what actually happened in Thailand both during and after the trial and to see what the critical lessons are, not just for researchers and funders, but also for advocates and communities who are continuing the work of finding new ways to end the AIDS epidemic."

Award-winning journalist Tom Paulson traveled to Thailand where he interviewed community leaders, government officials, researchers, trial participants, clinic staff and AIDS activists about what went right and what went wrong with the trial. The resulting report provides lessons about community engagement and approaches to international collaboration as well as important insights for developing trial protocols and planning for follow-up research once a trial is complete.

The Thai Way Forward is an excerpt from AVAC's annual state of the field report, Turning the Page, which will be released in July ahead of the International AIDS Conference.

As this report from Thailand makes clear, the search for an AIDS vaccine has been tumultuous and often divisive, much like the overall response to the AIDS epidemic.

"The global response to AIDS is in trouble. There are yawning gaps in funding for proven prevention and treatment and a crisis in political will for continued support of AIDS programs," Warren said. "We face skepticism about whether responding to AIDS is cost effective and whether limited funds for AIDS should include funding for AIDS prevention research. We have to meet this skepticism with honesty about what we know and clarity about the cause for hope that exists today in a way that it never has before."