51 Influenza Vaccine Programs with the Cell-Based Quadrivalent Influenza Vaccine and Adjuvanted Trivalent Influenza Vaccine are Highly Cost Effective in Canada

Abstract Background Influenza vaccination with quadrivalent egg-based vaccines (QIVe) in adults ≥ 65 years may be less effective due to immunosenescence. An MF59®-adjuvanted trivalent influenza vaccine (aTIV) has been developed to provide stronger, broader and longer protection in older adults. For the younger age groups, lower effectiveness may be associated to the mutagenesis of influenza viruses that are propagated in eggs. A cell- based quadrivalent influenza vaccine (QIVc) was developed to improve the vaccine effectiveness by eliminating egg-adaptation. Objectives The objective of this analysis was to evaluate the potential public health impact on the utilization of both vaccines in Canada. Design/Methods An SEIR dynamic-transmission model was created and adapted to four influenza strains for the 2013-2019 seasons. Strain-specific circulation was obtained from Canada’s national surveillance system. Influenza incidence estimates were calibrated using CDC published data. The model used rVE from peer reviewed publications for QIVc and aTIV showing superiority to QIVe vaccines. Frequency of egg-based genetic changes were estimated from a published review of Crick Institute reports. Estimates of specific vaccines efficacy and economic assumptions were derived from the published literature. Different vaccination scenarios, based on the provincial vaccination programs, were modelled. Results Replacing QIVe with QIVc in subjects 6 months-64 years led to an annual reduction of 462 156 symptomatic cases; 58 122 GP visits; 40,871 emerging consultations; 3 788 hospitalizations and 662 deaths versus a QIVe-for-all scenario. The adoption of QIVc and aTIV will be highly cost effective over the use of QIVe. aTIV would also be more cost effective than QIVHD. Table 1 provides the detailed results for the others scenario. Sensitivity analyses confirmed the robustness of the assumptions used in the analysis. Incremental analysis versus scenario QIVe for all Scenarios QIVe (6mo – 64 y) + aTIV (65y+) QIVe (6mo – 64 y) +QIVHD (65y+) QIVc 6m-64y +QIVe (65y+) QIVc (6m-64y)+ aTIV (65+) Symptomatic influenza cases -91 625 -101 043 -462 156 -550 070 GP consultations -12 106 -13 483 -58 122 -69 908 ED consultations -3 026 -3 371 -14 530 -17 477 Total number of hospitalizations -963 -1 058 -3 788 -4703 Total number of deaths -329 -356 -662 -961 Incremental cost effectiveness ratio Cost Saving $ CAD 70 743 $ CAD 3299 $ CAD 1384 Conclusion The greatest public health impact is obtain