title: The Clinical Impact and Cost Effectiveness of Quadrivalent Versus Trivalent Influenza Vaccination in Finland.
abstract: Trivalent influenza vaccines encompass one influenza B lineage; however, predictions have been unreliable on which of two antigenically distinct circulating lineages will dominate. Quadrivalent seasonal influenza vaccines contain strains from both lineages. This analysis assesses the cost effectiveness of switching from trivalent inactivated influenza vaccination (TIV) in Finland to quadrivalent vaccination, using inactivated (QIV) or live-attenuated (Q-LAIV) vaccines.
  
  
  
  A transmission model simulated the dynamics of influenza infection while accounting for indirect (herd) protection. Prior distributions for key transmission parameters were repeatedly sampled and simulations that fitted the available information on influenza in Finland were recorded. The resulting posterior parameter distributions were used in a probabilistic sensitivity analysis in which economic parameters were sampled, simultaneously encompassing uncertainty in the transmission and economic parameters. The cost effectiveness of a range of trivalent and quadrivalent vaccine policies over a 20-year time horizon was assessed from both a societal and payer perspective in 2014 Euros.
  
  
  
  The simulated temporal incidence pattern of symptomatic infections corresponded well with case surveillance data. A switch from the current TIV to Q-LAIV in children (2 to <18 years) and to QIV in other ages was estimated to annually avert approximately 76,100 symptomatic infections (95 % range 36,700-146,700), 11,500 primary care consultations (6100-20,000), 540 hospitalisations (240-1180), and 72 deaths (32-160), and was cost-saving relative to TIV (€374 million averted [€161-€752], in 2014 Euros, discounted at 3 %). This scenario had the highest probability of being the most cost-effective scenario considered.
  
  
  
  This analysis demonstrates that quadrivalent vaccination is expected to be highly cost effective, reducing the burden of influenza-related disease.
authors.affiliation: ICON Health Economics and Epidemiology, 100 Park Drive, Milton Park, Oxfordshire, OX14 4RY, Oxford, UK. richard.pitman@iconplc.com.
authors.forename: Lisa
authors.initials: L
authors.lastname: Nagy
authors.affiliation: Department of Pediatrics, University of Turku and Turku University Hospital, Turku, Finland.
authors.forename: Terho
authors.initials: T
authors.lastname: Heikkinen
authors.affiliation: AstraZeneca, Cambridge, UK.
authors.forename: Alfred
authors.initials: A
authors.lastname: Sackeyfio
authors.affiliation: ICON Health Economics and Epidemiology, 100 Park Drive, Milton Park, Oxfordshire, OX14 4RY, Oxford, UK.
authors.forename: Richard
authors.initials: R
authors.lastname: Pitman
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D003362:Cost-Benefit Analysis; D005387:Finland; D006760:Hospitalization / Q000191:economics; D006801:Humans; D032521:Immunity, Herd; D007252:Influenza Vaccines / Q000008:administration & dosage* / Q000191:economics; D007251:Influenza, Human / Q000191:economics / Q000517:prevention & control* / Q000821:virology; D018803:Models, Economic; D014611:Vaccination / Q000191:economics / Q000379:methods; D014613:Vaccines, Attenuated / Q000008:administration & dosage / Q000191:economics; D015164:Vaccines, Inactivated / Q000008:administration & dosage / Q000191:economics
chemical_list: D007252:Influenza Vaccines; D014613:Vaccines, Attenuated; D015164:Vaccines, Inactivated