Risk of Recurrence of Adverse Events Following Immunization: A Systematic Review

For vaccines to be fully effective and induce long-term protective immunity, individuals should receive all recommended doses. Vaccine recipients who experienced an adverse event following immunization (AEFI) are sometimes afraid that the adverse event might recur with future immunizations, and this can lead to avoidance or delay of subsequent immunizations. Most existing recommendations regarding the management of patients who had an AEFI are based on expert opinion and supported by limited scientific data. The aim of this systematic review was to summarize the literature on the risk of AEFI recurrence (defined as an occurrence of the same AEFI after the administration of another dose of the same vaccine or vaccines sharing common antigens) and identify predictors of recurrence. In addition, we sought to determine if the risk of an adverse event following reimmunization was higher in patients who already had the same adverse event at the previous immunization compared with those who did not. These results are expected to inform physicians when discussing continuation of immunization with patients who previously experienced an AEFI and to support future immunization guidelines for these patients.