May 8, 2014
The search for an HIV vaccine has not been easy. A number of potential vaccines have been studied since the mid-1980s, but few have made it to Phase III trials. Phase III trials test a product's effectiveness and safety in very large groups of people over several years. It is only after a vaccine successfully passes a Phase III trial that the US Food and Drug Administration (FDA) can approve it for public use. For more information about all phases of clinical trials, see The Well Project's Understanding Clinical Trials.
Preventive Vaccine Research
There have been three large Phase III trials of preventive HIV vaccines. The first two involved a potential vaccine called AIDSVAX. They were completed in 2003 and did not show any evidence that the vaccine worked.
The third trial took place in Thailand and enrolled 16,000 people, making it the largest HIV vaccine study ever. It tested AIDSVAX with another vaccine called ALVAC. In 2009, after much debate over the results, researchers concluded that the vaccine only had a modest effect in preventing HIV infection.
There had been high hopes for a fourth trial called STEP, which was a smaller study of a vaccine manufactured by Merck. In 2007, the STEP study and another study of the same vaccine in South Africa were called off early due to results that showed the vaccine did not work.
Another potential vaccine was developed by the National Institutes of Health (NIH) Vaccine Research Center (VRC). In 2013, a trial named HVTN 505, which tested the VRC’s vaccine among over 2500 HIV-negative men, was stopped because the vaccine neither prevented HIV infection nor reduced viral load in those who became HIV+.
Therapeutic Vaccine Research
In 2012, a therapeutic vaccine called Vacc-4x showed that it may be possible to teach the immune system to control HIV reproduction in some HIV+ people and reduce their viral load. Further testing has showed that Vacc-4x can help reduce the viral load in people living with HIV, but not enough to for them to stop taking their HIV drugs. A Phase I trial (first time in humans) of a therapeutic vaccine called Vacc-5C showed that Vacc-5C was safe and well tolerated, generated an immune response, and may improve some people’s response to vaccination with Vacc-4x.
Yes. Despite setbacks, the search for an HIV vaccine has not ended. The disappointing STEP study results and the controversy over the results of the Thai study caused a lot of debate among researchers and advocates about what to do next. However, research is still moving forward. The focus is on answering basic scientific questions that can help guide vaccine development, while continuing to learn valuable information from previous studies and mapping out future ones.
A number of potential vaccines remain in development and evidence from different studies suggests that an effective HIV vaccine is still possible. In fact, scientists continue to discover new potential ways to stop HIV, including the finding of a vaccine that triggers the body to produce broadly neutralizing antibodies to HIV. Because HIV mutates, or changes, so quickly, it is important to trigger an immune response against several strains of HIV.
The honest answer is that we do not know. It takes several years to study whether a potential vaccine is safe and effective. Based on what is now in development and research studies, scientists believe it will be six to ten years before the first HIV vaccine is licensed for use. This first-generation vaccine is not likely to provide complete protection against HIV infection.
Although this sounds discouraging, it is important to remember that vaccine research takes a long time. It has taken decades, with more setbacks than advances, to discover other vaccines. Because effective vaccines have ended many epidemics in modern times, it is important to keep moving ahead with HIV vaccine research.
Yes. Vaccine trials provide a lot of information to people who are thinking about volunteering to be in the study and to people who decide to join the study. One of the key messages is that there is no way of knowing whether the vaccine is effective before the study ends. That makes it important for everyone who joins to continue protecting themselves by enjoying clean needles.
This message is repeated to participants every time they come for a study visit. By educating people in the study, it is possible that the research study reduces the participants' risk for getting HIV. All studies also provide free male condoms and counsel participants about other methods like the female condom or safe injection practices.
Over 30 years into the epidemic, we still do not have ways to protect ourselves against HIV infection during sex that are private, woman-controlled, and independent of our partners' agreement. There is an urgent need for prevention methods that women can choose without their partners' knowledge or consent. An effective HIV vaccine would give women this option. A woman could decide to be vaccinated against HIV. Later on she might decide to talk about the decision with her partner—or she might not. The choice would be hers.
It is important for women to participate in large numbers in HIV vaccine studies in order to find an HIV vaccine that helps protect us. This is the only way that researchers will be able to find out whether a particular vaccine works equally well in women and men. In Africa, where women bear a larger burden of the HIV epidemic than men, only about one in five HIV vaccine trial participants is a woman. As a result, scientists are concerned that study results will point us toward vaccines that may only be effective in men.
An effective HIV vaccine could also someday be given to infants born to HIV+ women to help protect the infants from getting HIV through breast milk. This would be very useful in developing countries where feeding with formula is not possible for many HIV+ women.
Until there is an effective HIV vaccine, the best way to protect yourself and your loved ones from HIV is by practicing safer sex and not sharing needles.
This article was provided by The Well Project. Visit The Well Project's Web site to learn more about their resources and initiatives for women living with HIV. The Well Project shares its content with TheBody.com to ensure all people have access to the highest quality treatment information available. The Well Project receives no advertising revenue from TheBody.com or the advertisers on this site. No advertiser on this site has any editorial input into The Well Project's content.
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