Problems inherent in all the research strategies (case reports, passivesurveillance, LLDBs, and clinical trials) include the implicationsof not using unvaccinated children or adults as controls, a lackof information on the background incidence rates of the adverse reactions,long latencies for some reactions, and reactions with multifactorialetiologies. Basic research on both vaccines and the pathophysiologiesof adverse reactions should be continued.
SUMMARY
In sum, there was agreement that more consideration needs to be givento the use and utility of case reports, including those submittedto passive surveillance systems, that the role of clinical trials(including postmarketing studies) is limited due to frequent lackof randomization and small sample size, and that LLDBs show greatbut not unlimited promise. Vaccine safety must be studied on an ongoingbasis and with a variety of tools, including basic research.
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