The Canadian Immunization Research Network (CIRN) has been established to provide Canada with a national capacity to undertake coordinated, evaluative research to inform public health policy relating to vaccines and vaccination. Five existing PCIRN infrastructures have been transitioned into the new CIRN network, with the addition of three new networks. Like PCIRN, CIRN will act as a network of networks. The core infrastructure networks are the Clinical Trials Network (CTN), the Serious Outcomes Surveillance Network (SOS), the Canadian National Vaccine Safety Network (CANVAS), the Special Immunization Clinics Network (SIC), and the Provincial Collaborative Network (PCN). Three support networks working to assist the core infrastructures and facilitate projects are the Reference Laboratory Network (RLN), the Social Sciences and Humanities Network (SSHN), and the Modeling and Economics Research Network (ModERN).