# Cost-effectiveness of routine influenza vaccination program for individuals aged 65 years and older in Japan: Substituting standard-dose inactivated vaccine with high-dose inactivated vaccine

## TL;DR

This study assesses whether switching to a high-dose influenza vaccine for older Japanese people is cost-effective compared to the standard vaccine.

## Contribution

The paper provides age-specific cost-effectiveness thresholds for high-dose influenza vaccines in Japan.

## Key findings

- High-dose vaccines are cost-effective only if their price is less than 3.15 times standard vaccines.
- Cost-effectiveness is observed only for individuals aged 75 years and older.
- The incremental cost-effectiveness ratio for those aged ≥75 years is below the willingness-to-pay threshold.

## Abstract

•Cost-effectiveness of high-dose influenza vaccine (HD) among persons aged ≥65 years was examined.•Incremental cost-effectiveness ratios were presented not only for people aged ≥65 years but also for the following age groups: 65-69, 70-74, 75-79 and >80 years.•HD vaccination program was cost-effective if the price of HD was less than 3.15 times that of standard vaccines.•Age influences the incremental cost-effectiveness ratio, with the results being cost-effective only when the target age was ≥75 years.

Cost-effectiveness of high-dose influenza vaccine (HD) among persons aged ≥65 years was examined.

Incremental cost-effectiveness ratios were presented not only for people aged ≥65 years but also for the following age groups: 65-69, 70-74, 75-79 and >80 years.

HD vaccination program was cost-effective if the price of HD was less than 3.15 times that of standard vaccines.

Age influences the incremental cost-effectiveness ratio, with the results being cost-effective only when the target age was ≥75 years.

We evaluated cost-effectiveness of influenza immunization programs for protection of Japanese elderly (aged ≥65 years) from influenza-related diseases by comparing high-dose inactivated influenza vaccine (HD-IIV3) to standard vaccines (SD-IIV3).

Incremental cost-effectiveness ratio (ICER) from payers’ perspective was calculated. Variables used in the model were either calculated or extracted from literature. Quality-adjusted life years (QALYs) was used as measure of effectiveness. Cost per dose of HD vaccine was assumed to be four times of SD (JPY 1500/US$ 10).

In comparison to SD, HD gained more QALYs and reduced disease treatment costs, but these reduced costs did not offset vaccination cost. ICER for those aged ≥65 years was JPY 7,352,458/ US$ 49,016 per QALY, higher than the willingness-to-pay (WTP) threshold of JPY 5,000,000/US$ 33,333 per QALY. While ICER was JPY 50,477,31/US$ 33,652 for those aged ≥75 years. One-way sensitivity analysis revealed that relative vaccine effect against laboratory-confirmed influenza of HD to SD influenced the ICER the most. Monte Carlo simulations revealed that the probability of an ICER below WTP threshold was 20.9%.

For a WTP of JPY 5,000,000/US$ 33,333 per QALY gained, if the price of HD was four times the current vaccine, the seasonal HD-IIV3 vaccination program was not cost-effective for those aged ≥65 years, while was cost-effective for those aged ≥75 years.