Cost-Effectiveness and Value-Based Price of High-Dose Quadrivalent Influenza Vaccine Among Elderly Populations in Taiwan

OBJECTIVES: Elderly populations are recommended to receive high-dose quadrivalent influenza vaccine (HDQIV), given aging-related immunosenescence. However, whether the additional benefit generated by HDQIV justify its additional costs over standard-dose quadrivalent influenza vaccine (SDQIV) remains unclear. We therefore seek to assess the cost-effectiveness of HDQIV versus SDQIV and associated price reward to additional health gains from HDQIV in adults aged≥65 and 75 years old (y/o), separately.

METHODS: An economic simulation model with a lifetime horizon was employed to estimate the quality-adjusted life-years (QALYs) and costs (in 2022 USD) from a healthcare sector perspective, with both costs and QALYs discounted at 3% annually.Modelled parameters including vaccine effectiveness and costs were collected from the analysis of Taiwan’s National Health Insurance Research Database and literature reviews. Incremental cost-effectiveness ratio (ICER) was the primary outcome measure. Deterministic and probabilistic sensitivity, and scenario analyses were conducted for study robustness.

RESULTS: In base-case analyses, the ICERs were $32,156 and $20,583/QALY gained for the subjects aged≥65 and 75 y/o, respectively. The relative VE of HDQIV versus SDQIV on influenza-associated hospitalization was the most influential factor to economic results irrespective of subjects aged≥65 or 75 years old. Using HDQIV versus SDQIV is considered as highly cost-effective in 21%-99%/56%-99% of the model iterations at the willingness-to-pay threshold (WTP) of $32,756 in the subjects aged≥65/75 y/o, respectively. The ICERs varied by different scenarios, i.e., $9,396/$4,989 per QALY gained in the scenario of applying a broad definition for influenza events, $6,883/$3,765 per QALY gained in the scenario targeting heart disease-related hospitalizations, and $43,519/$28,056 per QALY gained in the worst scenario, in the subjects aged≥65/75 y/o, respectively. The value-based price difference between one-dose HDQIV and SDQIV was $25.48-$37.64/$38.94-$57.43 at $26,205-$39,307 (0.8*WTP-1.2*WTP) for the subjects aged≥65/75 y/o, respectively.

CONCLUSIONS: Using HDQIV is considered as highly cost-effective for Taiwanese elderly populations.