Between 1989 and 1994 the Institute of Medicine (IOM) carried out comprehensive reviews of the scientific evidence concerning the possible adverse effects of childhood vaccines. The studies, sponsored by the U.S. Public Health Service (PHS), were called for by the National Childhood Vaccine Injury Act of 1986 (Public Law 99-660) and resulted in the volumes Adverse Effects of Pertussis and Rubella Vaccines (Institute of Medicine, 1991), Adverse Events Associated with Childhood Vaccines: Evidence Bearing on Causality (Institute of Medicine, 1994a), and DPT Vaccine and Chronic Nervous System Dysfunction: A New Analysis (Institute of Medicine, 1994b). Among them, the committees evaluated the scientific evidence concerning the adverse effects of nine vaccines (for a total of more than 75 specific relations between vaccines and adverse events). Committee members were struck by the lack of evidence relating to causality for these adverse events. For about two-thirds of the relations evaluated, the committees found either that there was no evidence bearing on the question of causality or that the available evidence was insufficient or inadequate to make a determination about causality.

Cognizant of this problem, in late 1993 the PHS asked IOM to hold a scientific workshop to discuss the research strategies that could most fruitfully add to the assessment of the causal relation between vaccines and adverse events. The Committee to Study New Research on Vaccines, which had been charged primarily with the study that resulted in the 1994 DPT report, hosted such a workshop on December 7, 1993, in Washington, D.C. The intent of the workshop was not to address questions about specific vaccines or adverse events but to consider generally how questions about such topics should be addressed in future research. The workshop participants included academic researchers, members of vaccine safety advocacy groups, vaccine manufacturers, health care providers, representatives of federal research and regulatory agencies, and IOM staff. A list of participants is included at the end of this summary.

This document represents a summary of the workshop discussion. Although the workshop was held under the auspices of the Committee to Study New Research on Vaccines, this summary contains no committee recommendations, because committee consensus was not sought. The views stated in this summary are those of the individual workshop participants.

The discussion at the workshop was organized into three major areas: case reports and passive surveillance systems, large-linked databases (LLDBs), and clinical trials. For each topic, one or more individuals offered introductory comments, which were followed by a group discussion of the topic.