Another Candidate HIV Vaccine Fails: We Must Keep Trying
April 27, 2013
Senior Adviser, CSIS Global Health Policy Center
Yesterday, the National Institute of Allergy and Infectious Diseases (NIAID) of the U.S. National Institutes of Health (NIH) announced that it was stopping further testing of a candidate HIV vaccine combination (study HVTN 505). This step was taken after the independent experts who monitor the trial determined that it was unlikely to work based on data obtained from those already vaccinated.
This is disappointing for several reasons. First, for the 2500 study volunteers, who are men who have sex with men (MSM) or transgendered, over 48 were infected after having been in the study a minimum of 28 weeks – the annual equivalent of an incidence of over 2%. This is a very high rate, and even more alarming because they all received state-of- the art prevention support, including counseling and condoms. This raises questions about the effectiveness of prevention approaches and reminds us powerfully why an effective vaccine is so desperately needed.
Second, this was an exciting product for scientists. While the NIH was criticized for moving ahead with this study after a similar product failed in an earlier trial, it persevered. The approach used was called “prime boost”, in which a primary vaccination with one product is followed by a booster shot of another. Injected are genetic parts of the inside and outside of the virus, introduced into the immune system by an inert viral vector. Any time a viable product fails in a study, it means yet another delay – often years – before the next promising product appears. More importantly, another failure erodes confidence in the feasibility of ever finding a vaccine.
It’s that erosion of confidence that must be reversed. A vaccine will be essential to bringing HIV to an end. More can be done with what we have, but elimination and eventual eradication can’t be achieved without a cheap, safe, and effective vaccine. So the hope is that scientists can still learn from this study, and use that to improve the success of future efforts. Thankfully, NIAID has announced that while it will stop vaccinations, it will continue to follow study volunteers.
While several other countries contribute, the U.S. leads the world in this effort through government efforts sponsored by NIH, USAID and the Department of Defense, and through the work of a wide variety of U.S.-based non-profits like the International AIDS Vaccine Initiative, AVAC, and the Global HIV Vaccine Enterprise, foundations like the Bill & Melinda Gates Foundation, and small and large for-profit vaccine and biomedical companies. In this study, we also have 2,500 Americans who volunteered for the study (thank you).
While this is a disappointing turn of events, perseverance is needed. HIV is an incredibly tough and adaptive virus that’s had a century to wind its way into the deepest recesses of the human immune system, so we shouldn’t be surprised that it’s taking a few decades to find a way to stop it.