SPf66 vaccine trial in Brazil: conceptual framework study design and analytical approach.

This paper describes the study population and the study design of the phase III field trail of the SPf66 vaccine in Brazil. Assessment of validity and precision principles necessary for the appropriate evaluation of the protective effect of the vaccine are discussed, as well as the results of the preliminary analyses of the gathered data. The analytical approach for the estimation of the protective effect of the vaccine is presented. This paper provides the conceptual framework for future publications.