Cost-effectiveness analysis of pertussis booster vaccination for adolescents in Japan

Introduction: In Japan, the introduction of a fifth diphtheria-tetanus-acellular pertussis (DTaP) vaccination has been considered, and adolescents aged 11-12 years old who are currently receiving the diphtheria-tetanus (DT) vaccine are one candidate group. We analyze the cost-effectiveness of replacing the DT vaccine with the DTaP vaccine for 11 -year -old adolescents and investigate the indirect effect of vaccinated adolescents on unvaccinated infant siblings. We undertake two analyses using high- and low -morbidity pertussis cases, and based on the results, present suggestions for pertussis prevention in the post-COVID-19 pandemic era. Method: We used the number of pertussis cases in 2019 as the high -morbidity case and the average number of cases in 2020-2021 as the low -morbidity case, and evaluated the incremental cost-effectiveness ratio (ICER) of the DTaP strategy to the DT strategy based on quality -adjusted life years (QALYs). The economic model contained adolescent and infant sub -models. The indirect effect for infants was considered as the probability of unvaccinated infants avoiding pertussis infection from their vaccinated siblings. Results: The ICER from the payers' perspective was Japanese yen (JPY) 4,254,515 per QALY gained in the high -morbidity case and JPY 62,546,776 per QALY gained in the low -morbidity case. The sensitivity analysis showed that the utility of pertussis had the greatest impact on the ICER, with a 60.58% and 0% probability that the ICER was less than JPY 5 million per QALY gained in the high -morbidity case and low -morbidity case, respectively. Conclusion: The cost-effectiveness of replacing the DT vaccine with the DTaP vaccine is affected by the level of pertussis morbidity, with the ICER becoming more favorable in the high -morbidity case. The indirect effect has little impact on the ICER. Thus, policy -makers should continue to monitor the pertussis epidemic in the post-COVID-19 era, and determine the need to introduce a booster based on perceived trends.