Enormous strides have been made in the last decade toward the development of malaria vaccines based on antigens of the pre-erythrocytic stages of the parasite. Impressive progress has also been made towards transmission-blocking vaccines (although no vaccine in this category has been tested in humans as yet, such a trial is planned). These efforts target two of the three most vulnerable stages of the parasite life cycle and could, if successful, serve as the basis for vaccines that protect both individuals and communities. However, these vaccines may be effective in less than 100% of the vaccinated individuals, and there might be little effect on malaria morbidity and mortality in individuals who become infected in spite of their use. Many workers believe that vaccines against blood stages could be effective in this regard.
One blood-stage vaccine, based on a synthetic peptide antigen designated as SPf66, developed by Dr. Manuel Patarroyo and coworkers, has been reported to be efficacious under certain conditions, encouraging further work in this area.