A system and a method for surveying and assessing the contribution of drugs risks of adverse events, comprising a) identification and studying: a plurality of case-groups of different categories of adverse events, each case of a given case-group being faced with a given adverse event; a pool of potential referents identified regardless of a previous medical history thereof; and a large number of drugs and vaccines used by the cases and the potential referents; b) selecting controls sampled from the pool of potential referents according to predetermined criteria; c) matching the controls to specific cases of the case-groups; and d) conducting statistical analyses by comparing cases and controls to identify drugs that are susceptible to be associated with a modified risk of at least one of the adverse events and factors associated with this risk; wherein the steps a) to d) are performed on a systematic prospective on-going plan.