It is possible to reduce the risk of HIV infection with a vaccine: AVAC

Sep 24 2009

"Today marks an historic milestone in the search for an AIDS vaccine; we now have evidence that it is possible to reduce the risk of HIV infection with a vaccine," said AVAC executive director Mitchell Warren, reacting to the results of the first AIDS vaccine trial to ever show efficacy at preventing HIV. "It will take time and resources to fully analyze, understand and validate the data, but there is little doubt that this finding will energize and redirect the AIDS vaccine field as all of us begin the hard work to translate this landmark result into true public health benefit."

"We congratulate the trial sponsors, scientific collaborators and partners who conducted this trial, and especially want to thank the more than 16,400 Thai men and women whose altruism and commitment as trial volunteers made this effort possible. These volunteers and their communities have made an inestimable contribution to HIV prevention research. We all owe them a debt of gratitude," Warren said. "As we move forward in our search for vaccines and other new HIV prevention interventions, researchers will need the collaboration of tens of thousands more volunteers around the world in additional trials. We are confident that many more communities and individuals will follow in their footsteps."

As the trial team reported in Bangkok today, the Thai prime-boost trial found that rates of HIV infection were roughly 30 percent lower among volunteers who received the vaccine versus those who received the placebo. This is the first evidence of an AIDS vaccine providing any level of protection against HIV infection. Statistical analyses presented as part of this initial announcement support the validity of the finding. It is important to remember that the trial was a "test of concept" study designed to identify initial signs of promise in a product. The trial sponsors and implementers, led by the US Military HIV Research Program and funded by the National Institutes of Allergy and Infectious Diseases (NIAID), have been clear that additional studies would be needed to further understand any positive result. There is now an imperative on the trial team and the field as a whole to determine what those steps will be and to implement them with all due haste. Additional analysis of the trial data are expected to be presented at the annual AIDS vaccine meeting that will take place in October.

The trial looked at vaccine impact on risk of infection and on viral load among vaccine and placebo recipients who received the vaccine and went on to acquire HIV. The vaccines themselves are not capable of causing infection. There was no evidence of an impact on viral load -- a goal that has been embraced by many vaccine stakeholders as more realistic and attainable than an impact on risk of infection.

"These results move us one step further along in the marathon journey of AIDS vaccine research that continues. They also demonstrate that the scientific process is remarkable and unpredictable, and underscores the need for testing strategies in human efficacy trials. We look forward to more data from the trial in the coming weeks that will help guide the decisions about the design of additional trials of this strategy, and the impact of this finding on broader AIDS vaccine research," Warren said.

"AVAC calls on the trial sponsors, vaccine manufacturers, researchers, funders and others in the field to work quickly, cooperatively and boldly to translate these results into development of a scientific action plan, a plan for community engagement in Thailand and around the world, and a broader communication effort to convey both the promise and limitations of this result. Above all, we must ensure that all stakeholders, including private industry -- which played a critical role in this trial -- reaffirm their commitments to work that will lead to eventual access to an effective vaccine for people around the world, " Warren said.

The trial team and Thai collaborators held extensive consultations to determine next steps in various scenarios and determined that a vaccine effect of 50% or higher would trigger a licensure application in Thailand. This finding does not reach this threshold. The same consultations determined that a modest effect, such as was reported today, would trigger additional discussions about the way forward. These new consultations are an essential next step and should include a range of stakeholders including members of communities that might use such a vaccine.

Stakeholders within Thailand and around the world must recognize and rise to the challenge of explaining the promise of this proof of concept as well as the rationale for proceeding with a thorough consultative process and data analysis before making any decisions about future access.

It is important to note that the two vaccines tested in the Thai trial contain synthetic fragments of subtype E, one of the most common HIV strains circulating in Thailand and Southeast Asia. The regimen also contains subtype B, which is most common in North America and Europe. Therefore this result estimates the level of protection conferred by a vaccine that includes genetic fragments matched to the common circulating subtype. Scientists do not know whether a vaccine that is effective against the strains that are found in a given geographical area will also be effective in other areas and against other strains of HIV. The trial collaborators and other experts are already planning follow-up studies to confirm and elaborate on this and other findings from this trial.

"This is an astonishing scientific achievement, well beyond the expectations of many scientists. It starts a new chapter in the search for an HIV vaccine: to make highly protective vaccines that can be made available to all who need them. There is a great deal of work to be done on many fronts at once, and AVAC is fully committed to hastening that day. We need to enlist a larger number of new vaccine advocates to keep the process moving productively as quickly as feasible," said Bill Snow, an AIDS vaccine activist since 1991, and a co-founder of AVAC in 1995.

There are also still other HIV vaccine strategies in laboratory and human testing. Furthermore, other HIV prevention options, particularly microbicides and pre-exposure prophylaxis, or PrEP, are being tested in efficacy trials which will yield results in the next few years. In the last few years, clinical trials have also shown that medical male circumcision can be effective at reducing the risk of HIV infection in heterosexual men.

"This step adds immensely to the drive for comprehensive HIV prevention," Warren added. "That means perfecting methods and ensuring access for all who need it to existing HIV prevention and treatment options, including male and female condoms, behavior change counseling, male circumcision, clean needles, harm reduction and antiretroviral drugs; ensuring continued research to find effective new options, including vaccines, microbicides, and PrEP; and planning for integrating these new interventions into combination programs."

Source: http://www.avac.org