Detecting and Responding to Adverse Events Following Vaccination: Workshop Summary
Cynthia J. Howe, Richard B. Johnston, and Gerald M. Fenichel, Editors
On November 6, 1995, the Institute of Medicine's Vaccine Safety Forum convened a workshop on detecting and responding to adverse events following vaccination. Workshop speakers and participants discussed the difficulties in detecting adverse events, current adverse events detection and response methods and procedures, suggestions for improving the means of detecting and responding to adverse events following vaccination, and future areas of research. This document represents a summary of that workshop.
The detection of adverse events following vaccination includes a range of activities. At one extreme it involves the realization that a specific event might be associated with vaccination and the reporting of that case to appropriate authorities. At the other extreme, detection of adverse events includes the assessment of a statistical pattern that suggests that a particular adverse event might be associated with or caused by a particular vaccine. A number of factors make it difficult to detect adverse events associated with vaccination and to determine whether the event is causally associated with the administration of a vaccine: (1) the need to study multiple exposures and multiple outcomes, (2) the lack of unique vaccine-associated syndromes, making it difficult to establish causality, (3) the need for large sample sizes and lack of large computerized immunization databases with individual level data including vaccine lot number, (4) brief exposure periods for each individual, (5) high vaccination coverage makes unvaccinated individuals highly selected.