Fig. 1: Flow chart of the study protocol for this polio booster immunization clinical trial.
From: Evaluation of the immunization effectiveness of bOPV booster immunization and IPV revaccination

IPV inactivated poliovirus vaccine, bOPV bivalent oral poliovirus vaccine. Blue box: immunopersistence study, which is not within the scope of the present analysis; red boxes: descriptions of the situations of those who did not participate in this booster immunization clinical trial.