The malaria vaccine: anti-parasite or anti-disease?

There are three major difficulties hindering the development of a vaccine for malaria. First, for all three stages of the parasite life cycle there is an incomplete understanding of the precise type of immune response to aim for. Second, only a handful of the many hundreds of parasite-derived antigens have been explored, and though several have been shown to be protective in animal models, it is not known if they are the most potent. Third, there is strong evidence that the parasite can evade host immunity, for example by antigenic variation. In this brief article, John Playfair and his colleagues address mainly the first issue and suggest that complete resistance to infection is probably not feasible, and that attention should be directed not so much at vaccines designed to eliminate one or other stage of the parasite, but rather towards the possibility of an 'antitoxic' vaccine that prevents the serious pathological complications of the disease.