[Clinical research design and causality: does oral rotavirus vaccine cause intussusception?].

Design of clinical research whose purpose is to answer questions about causality can be classified in relation to four axes: the number of study groups, the implementation of an experimental maneuver, cause-effect directionality and source from which the data are collected. The basic designs used in epidemiology are the clinical trial, the cohort study, the case-control study and the cross-sectional survey. This text aims to facilitate the identification and understanding of each of these designs through examples related to the association between rotavirus vaccination and intussusception.