Fig. 1

Summary of the current state of knowledge of this history of pertussis epidemiology in Canada: Yearly incidence rates for total reported cases of pertussis since the start of national reporting in 1924 (blue), and yearly incidence of cases without age information (red). Prior to 1952, no age information was reported at all. See Fig. S1 for a more detailed view of the period 1952–2015. In most years between 1969 and 1988, the majority of cases had no age information