The discipline of pharmacovigilance (PV) largely originated in reaction to public health disasters caused by medications. Sidney Kahn at Sciformix Corporation looks into the approaches for detecting significant, previously unrecognized hazards of medications after their introduction into clinical use, and how this has been principally based on collecting anecdotal reports of suspected adverse drug reactions.
https://international-pharma.com/wp-content/uploads/2013/10/Sciformix-final-1.pdf