Figure 2.

Change in emergency department (ED) visits with cough (relative risk and 95% confidence interval) associated with a one-case increase in notifications of pertussis, lagged from −14 to +14 days: Univariate analysis¹. 1. A negative lag refers to notified pertussis cases (taken as date of disease onset) occurring after ED visits with cough. A positive lag refers to notified pertussis cases occurring before ED visits with cough. Relative risks refer to changes in ED visits resulting from every additional notification of a case of pertussis.