“An effective AIDS vaccine could be found as early as 2012, saving 6 million lives if the world is willing to put £10 bn a year into a new programme, the chancellor, Gordon Brown, said in a speech last night in Tanzania”. Faith in biomedical science; the conviction that new vaccines will be translated into lives saved; belief in the necessity of globally concerted action: the British minister's statement reflects views of vaccine innovation that are widely held today. New and improved vaccines seem our best hope of coping with the scourge of AIDS, of arming ourselves against the unknown threats of emergent diseases and potential bioterrorism, and of tackling the resurgence of old diseases arising once more in Europe. Global coordination, pooling our resources, seems self-evidently necessary, given the international nature of a modern epidemic. Much current discussion of vaccine development and use thus has a global character. That is to say, it is conducted under the banner of global slogans or it seeks to establish globally integrated approaches to vaccine research and development (R&D). Over the past two decades the development and rapid introduction of new vaccines have come to dominate the vaccine agenda worldwide. Social scientists and health policy analysts have been set to work, examining barriers to the implementation of international priorities at the national level. Why, for example, are national responses to the availability of new vaccines often so lethargic? A recent study of the adoption of Hemophilus influenza b (Hib) conjugate vaccine is a good example. It shows policy makers in four countries rationally weighing the burden to public health of the diseases against which the vaccine offers protection (bacterial meningitis and pneumonia), against the high cost of the vaccine. Health policy analysts tend to explain the decision to introduce a new vaccine, or to replace an existing vaccine by a new alternative, in terms of the epidemiology and seriousness of the disease, and of scientific ...