Integrated sentinel surveillance linking genetic, antigenic and epidemiologic monitoring of influenza vaccine-virus relatedness and effectiveness, 2013-14 season

 Canada's Sentinel Physician Surveillance Network (SPSN) links genetic, antigenic and vaccine effectiveness (VE) measures in an integrated platform of influenza monitoring, described here for the 2013-14 season of resurgent A(H1N1)pdm09 and late-season influenza B activity.  VE was estimated as [1-OddsRatio]x100% comparing vaccination status between influenza test-positive cases and test-negative controls. Vaccine-virus relatedness was assessed by genomic sequence analysis and hemagglutination-inhibition assay.  Analyses included 1037 controls (33%vaccinated) and 663 cases (15%vaccinated): 415 A(H1N1)pdm09, 15 A(H3N2), 191 B/Yamagata-lineage, 6 B/Victoria-lineage, 36 unknown subtype/lineage. A(H1N1)pdm09 viruses belonged to clade-6B, distinguished by a K163Q substitution, but remained antigenically-similar to A/California/07/2009-like vaccine with adjusted-VE of 71%(95%CI=58-80%). Most (83%) B/Yamagata-lineage viruses clustered phylogenetically with the prior 2012-13 season'...