Thirty years have passed since the recognition of the infectious disease now named acquired immune deficiency syndrome (AIDS). In that relatively short time AIDS has killed over 30 million individuals, and an additional 33.3 million people are now living with the infection. Africa shoulders the burden of the epidemic: UNAIDS estimates that in 2009 1.3 million people died from AIDS in Africa, 22.5 million were living with HIV, and a further 1.5 million acquired the infection during the year. Even though prevention and treatment programs are expanding, the epidemic is holding its ground. Only two out of every five people requiring anti-retroviral therapy currently have access to treatment – and this number is threatened by financial pressures of the global recession. Though universal access to treatment is a morally compelling goal, the high costs associated with treatment argue for a strategy that emphasizes prevention.

An AIDS vaccine is the ultimate goal of prevention – vaccination would provide a manageable and affordable way to confer protection against HIV infection. When fully developed and licensed, an AIDS vaccine could have a powerful and immediate impact; the International AIDS Vaccine Initiative (IAVI) estimates that an AIDS vaccine of 50 percent efficacy given to just 30 percent of the population could reduce the number of new infections in the developing world by 24 percent in fifteen years (IAVI 2009a). Yet AIDS vaccine development is proving to be enormously expensive. Is the perhaps $15–20 billion of additional resources that it may cost the world to develop an AIDS vaccine worth it?