Fig. 1
From: The use of relative incidence ratios in self-controlled case series studies: an overview
Frequency of ER visits and hospital admissions in the 3 weeks before and after vaccination (DTaP-IPV-Hib at 6 months of age): Illustration of the impact of the healthy vaccinee effect: Data from Ontario, Canada [22]. Count = number of combined endpoints of emergency room visit, hospitalization and death. Days since vaccination = number of days before or after vaccination, day 0 being the day of vaccination