The self-controlled case series method for evaluating safety of vaccines

Using cases as their own controls potentially provides stronger evidence for analysing adverse events following vaccination

Maintaining public confidence in vaccines requires having effective postmarketing vaccine safety surveillance systems in place to rapidly address emerging concerns about vaccine safety. However, conducting studies of vaccine safety presents several challenges for traditional observational study designs. Important differences may exist between vaccinated and unvaccinated individuals that could confound the true association of interest between vaccination and adverse events. In practice, it is often difficult or impossible to adequately control statistically for these differences, either because confounders are unmeasured or unmeasureable, or because of the scarcity of unvaccinated controls when studying population-wide immunisation programs.