Beyond antigenic match: possible agent-host and immuno-epidemiological influences on influenza vaccine effectiveness during the 2015–16 season in Canada

Vaccine effectiveness (VE) estimates are reported from Canada’s Sentinel Practitioner Surveillance Network (SPSN) for the 2015–16 influenza season, characterized by a delayed A(H1N1)pdm09 epidemic and concurrent B(Victoria) activity. Potential influences beyond antigenic match are explored including viral genomic variation, birth cohort effects, prior vaccination and epidemic period.