Effectiveness of trivalent seasonal influenza vaccine in preventing laboratory-confirmed influenza in primary care in the United Kingdom: 2012/13 end of season results

N. Andrews , J. Mcmenamin , H. Durnall , J. Ellis , A. Lackenby , C. Robertson (1, 2, 3) , B. Von Wissmann , S. Cottrell , B. Smyth , C. Moore , R. Gunson , M. Zambon , D. Fleming , R. Pebody

1 Health Protection Scotland
2 IPRI - International Prevention Research Institute
3 University of Strathclyde [Glasgow]

The effectiveness of the 2012/13 trivalent seasonal influenza vaccine (TIV) was assessed using a test-negative case-control study of patients consulting primary care with influenza-like illness in the United Kingdom. Strain characterisation was undertaken on selected isolates. Vaccine effectiveness (VE) against confirmed influenza A(H3N2), A(H1N1) and B virus infection, adjusted for age, sex, surveillance scheme (i.e. setting) and month of sample collection was 26% (95% confidence interval (CI): -4 to 48), 73% (95% CI: 37 to 89) and 51% (95% CI: 34 to 63) respectively. There was an indication, although not significant, that VE declined by time since vaccination for influenza A(H3N2) (VE 50% within three months, 2% after three months, p=0.25). For influenza A(H3N2) this is the second season of low VE, contributing to the World Health Organization (WHO) recommendation that the 2013/14 influenza vaccine strain composition be changed to an A(H3N2) virus antigenically like cell-propagated prototype 2012/13 vaccine strain (A/Victoria/361/2011). The lower VE seen for type B is consistent with antigenic drift away from the 2012/13 vaccine strain. The majority of influenza B viruses analysed belong to the genetic clade 2 and were antigenically distinguishable from the 2012/13 vaccine virus B/Wisconsin/1/2010 clade 3. These findings supported the change to the WHO recommended influenza B vaccine component for 2013/14.

Mots clés: Adolescent Adult Aged Case-Control Studies Child Female Great Britain/epidemiology Hemagglutination Inhibition Tests Humans Influenza A Virus; H1N1 Subtype/classification/genetics/immunology/*isolation & purification Influenza A Virus; H3N2 Subtype/classification/genetics/immunology/*isolation & purification Influenza B virus/genetics/*immunology/isolation & purification Influenza Vaccines/*administration & dosage/immunology/therapeutic use Influenza; Human/*epidemiology/immunology/*prevention & control/virology Male Middle Aged Primary Health Care Reverse Transcriptase Polymerase Chain Reaction Seasons *Sentinel Surveillance Sequence Analysis; DNA Time Factors Treatment Outcome Vaccination/statistics & numerical data

Domaines: Santé publique et épidémiologie

N. Andrews, J. Mcmenamin, H. Durnall, J. Ellis, A. Lackenby, et al.. Effectiveness of trivalent seasonal influenza vaccine in preventing laboratory-confirmed influenza in primary care in the United Kingdom: 2012/13 end of season results. Euro Surveill, 2014, 19 (27), pp.5-13. ⟨hal-01262537⟩