title: Cost-effectiveness analysis of quadrivalent influenza vaccine versus trivalent influenza vaccine for elderly in Hong Kong.
abstract: BACKGROUND
  Cost and quality-adjusted life-years (QALYs) gained by quadrivalent influenza vaccine (QIV) versus trivalent influenza vaccine (TIV) in Hong Kong elderly were estimated over 9 seasons.
  
  
  METHODS
  TIV-unmatched influenza B infection rates with QIV versus TIV were estimated by an epidemiology model. Model parameters included percentages of influenza B lineages in circulation, influenza B-associated hospital admission, age-specific population, vaccine coverage and effectiveness. Incremental cost per QALY gained (ICER) by QIV versus TIV were estimated from Hong Kong's societal perspective.
  
  
  RESULTS
  Mean reduction in influenza B infection rate was 191.3 (95%CI 45.1-337.5) per 100,000 population aged ≥65 years. Highest cost savings and QALYs gained by QIV occurred in 2007 with high percentage of TIV-unmatched strain (92.9%) for age groups 65-79 years (USD266,473 and 22.8 QALYs) and ≥80 years (USD483,461 and 27.3 QALYs). ICERs of QIV were below willingness-to-pay for age group 65-79 years in 6, 5 and 3 years when QIV cost + USD1 + USD2 and + USD5 more than TIV, respectively. For age group ≥80 years, ICERs of QIV were below willingness-to-pay in 7 and 5 years when QIV cost + USD1 and + USD5, correspondingly.
  
  
  CONCLUSIONS
  Acceptance of QIV to be cost-effective in Hong Kong elderly was subject to QIV unit cost and percentage of circulating TIV-unmatched influenza B lineages.
authors.forename: Joyce H S
authors.initials: JH
authors.lastname: You
authors.forename: Wai-kit
authors.initials: WK
authors.lastname: Ming
authors.forename: Paul K S
authors.initials: PK
authors.lastname: Chan
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000914:Antibodies, Viral; D003362:Cost-Benefit Analysis; D005260:Female; D006385:Hemagglutination Inhibition Tests; D006723:Hong Kong; D006760:Hospitalization / Q000191:economics; D006801:Humans; D009981:Influenza B virus / Q000276:immunology; D007252:Influenza Vaccines / Q000191:economics / Q000276:immunology / Q000627:therapeutic use*; D007251:Influenza, Human / Q000191:economics / Q000517:prevention & control*; D008297:Male; D018803:Models, Economic; D019057:Quality-Adjusted Life Years; D012621:Seasons
chemical_list: D000914:Antibodies, Viral; D007252:Influenza Vaccines