Adverse events associated with vaccines are currently detected through the Public Health Service's Vaccine Adverse Event Reporting System (VAERS), the Centers for Disease Control and Prevention's (CDC's) Large Linked Data Base (LLDB),1 and through surveillance measures undertaken by vaccine manufacturers. The federal agencies primarily responsible for responding to the adverse events associated with vaccines are the Food and Drug Administration (FDA) and CDC. the efforts made by CDC, FDA, and vaccine manufacturers to detect and respond to adverse events following vaccination have been effective in many cases, but there are limits to the detection and response systems currently in use Workshop participants expressed a wide diversity of opinions on priorities for change and improvements and on the scientific basis for some of the suggestions presented. Participants suggested that efforts can be made to improve the quantity, quality, accessibility, and usefulness of VAERS reports. Routine, systematic screening of data, as well as other procedures, can be developed to make LLDB data more useful. The use of larger and better-designed clinical trials conducted both before and after a vaccine's licensure for general use could also be considered to improve the rate of detection of rare adverse events. Such trials could be designed to help separate out the effects of vaccines used in combination and to determine whether certain vaccine combinations pose more risk than vaccines given separately. Vaccine recall procedures could be improved as well.
More research could be done on potential long-term adverse effects from vaccines as well as the potential of vaccines to induce or worsen immune disorders. Research also could usefully address such questions as whether age is a factor in the adverse events experienced following vaccination and whether some groups of individuals are more prone to such adverse effects than others.
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. These and other aspects of vaccine safety were discussed by the workshop participants. These issues were also covered in an earlier IOM report Research Strategies for