Disparities in co-payments for influenza vaccine among the elderly, during the COVID-19 pandemic in Japan

Introduction: Seasonal influenza vaccination for the elderly is highly recommended during the COVID-19 pandemic. In Japan, the amount of subsidy for influenza differs among municipalities. Thus, we investigated the amount of and variation in subsidy for influenza vaccination for the elderly in 2020. Methods: This was an ecological study of 1,922 municipalities in Japan. The amount of subsidy for influenza vaccines for the elderly in each municipality was surveyed through websites or via telephone. Geographic and financial data for municipalities and prefectures were obtained from the open data. The amount of co-payment for the influenza vaccine and the geographical and financial status of each municipality were compared, according to the aging rate. Univariate logistic regression analysis was performed to explore factors related to the free influenza vaccine. Results: Municipalities with higher aging rates tended to have higher median co-payments for vaccines in 2020. (0 yen vs 1000 yen, p < 0.001) In addition, they tended to have worse financial conditions and lower per capita incomes. A similar trend was observed in the analysis by prefecture, i.e., a higher influenza mortality rate in prefectures with a higher aging rate. Despite having lower incomes, municipalities and prefectures with higher aging populations had higher mortality rates from influenza and higher co-payments for influenza vaccination. Conclusions: In Japan, there is a disparity among elderly people; areas with an aging population have higher co-payments for influenza vaccines despite lower incomes, suggesting that the government needs to implement corrective measures to reduce this disparity.