Subject(s)
Influenza A Virus, H3N2 Subtype/isolation & purification , Influenza Vaccines/administration & dosage , Influenza, Human/epidemiology , Influenza, Human/prevention & control , Physicians, Family , Sentinel Surveillance , Adolescent , Adult , Aged , Aged, 80 and over , Antigens, Viral/analysis , Canada/epidemiology , Case-Control Studies , Child , Child, Preschool , Female , Hemagglutination Inhibition Tests , Humans , Infant , Influenza A Virus, H3N2 Subtype/genetics , Influenza A Virus, H3N2 Subtype/immunology , Influenza Vaccines/immunology , Influenza, Human/diagnosis , Influenza, Human/virology , Male , Middle Aged , Molecular Sequence Data , Nasopharynx/virology , Nose/virology , Outcome Assessment, Health Care , Polymerase Chain Reaction , Sequence Analysis, DNA , Vaccination/statistics & numerical dataABSTRACT
The 2013/14 influenza season to date in Canada has been characterised by predominant (90%) A(H1N1)pdm09 activity. Vaccine effectiveness (VE) was assessed in January 2014 by Canada's sentinel surveillance network using a test-negative case-control design. Interim adjusted-VE against medically-attended laboratory-confirmed influenza A(H1N1)pdm09 infection was 74% (95% CI: 58-83). Relative to vaccine, A(H1N1)pdm09 viruses were antigenically similar and genetically well conserved, with most showing just three mutations across the 50 amino acids comprising antigenic sites of the haemagglutinin protein.
Subject(s)
Influenza A Virus, H1N1 Subtype/isolation & purification , Influenza Vaccines/administration & dosage , Influenza, Human/epidemiology , Influenza, Human/prevention & control , Sentinel Surveillance , Adolescent , Adult , Aged , Canada/epidemiology , Case-Control Studies , Child , Child, Preschool , Female , Hemagglutination Inhibition Tests , Humans , Infant , Influenza A Virus, H1N1 Subtype/genetics , Influenza A Virus, H1N1 Subtype/immunology , Influenza Vaccines/immunology , Influenza, Human/diagnosis , Influenza, Human/virology , Nasopharynx/virology , Nose/virology , Outcome Assessment, Health Care , Real-Time Polymerase Chain Reaction , Seasons , Sensitivity and Specificity , Sequence Analysis, DNA , Vaccination/statistics & numerical dataABSTRACT
The 2012/13 influenza season in Canada has been characterised to date by early and moderately severe activity, dominated (90%) by the A(H3N2) subtype. Vaccine effectiveness (VE) was assessed in January 2013 by Canada's sentinel surveillance network using a test-negative case-control design. Interim adjusted-VE against medically attended laboratory-confirmed influenza A(H3N2) infection was 45% (95% CI: 13-66). Influenza A(H3N2) viruses in Canada are similar to the vaccine, based on haemagglutination inhibition; however, antigenic site mutations are described in the haemagglutinin gene.