33. Vaccine Safety

Summary

Pre-licensure vaccine testing is stringent. However, even the largest trials will not detect very rare adverse events and may exclude special populations. To protect the public health and improve the safety of vaccines, comprehensive post-licensure safety monitoring systems are needed. The primary objectives of post-marketing surveillance and research are to detect rare adverse events and assess their causal relationship to vaccination, monitor the safety of new vaccines, and ascertain risk factors for adverse reactions to vaccines. These goals are accomplished through passive surveillance using spontaneous reporting, active surveillance, and controlled epidemiologic studies, the latter two utilizing large linked databases. Passive reporting is primarily used to generate hypotheses about adverse events deserving of further study. Active surveillance and epidemiologic studies test hypotheses and yield information about whether or not studied events are causally related to vaccination. Recent advances in vaccine safety science include near real-time monitoring of new vaccines, clinical research on pathophysiologic factors underlying adverse events, and standardized adverse event case definitions.