Vaccination strategies, public health impact and cost-effectiveness of dengue vaccine TAK-003: A modeling case study in Thailand.

Background: Dengue is an increasing global problem associated with negative health and economic impacts. Vaccination is an important measure to reduce the significant public health and economic burden caused by dengue. Our study assesses the public health impact and cost-effectiveness of a new dengue vaccine, TAK-003, using Thailand as a case study.

Methods and findings: We developed a dynamic transmission model with both host and vector populations, 4 serotype-specific infections, seasonality, and other key elements of dengue natural history. We estimated efficacy of TAK-003 from the DEN-301 trial. We first used the model to determine the optimal cohort age for different vaccination strategies with TAK-003, based on Thai dengue epidemiology. Secondly, we assessed the public health impact of a pragmatic strategy integrating TAK-003 into an existing national immunization program in Thailand. Cost-effectiveness was evaluated from a societal perspective using disability-adjusted life-years (DALYs) over a 20-year horizon. TAK-003 is estimated to prevent 41%-57% of symptomatic cases and 47%-70% of hospitalizations, with the greatest impact observed when routinely vaccinating children aged 6 years with 10 additional catch-up cohorts. This strategy resulted in 104,415 fewer DALYs and savings of US$1,786 million. If introduced into the national immunization program at 11 years of age (alongside the existing human papillomavirus vaccine), TAK-003 is estimated to prevent 44% of symptomatic cases and 53% of hospitalizations. This strategy prevented 87,715 DALYs and saved US$1,346 million. Sensitivity analyses demonstrated that the results were robust. The main limitations were inherent to the assumptions and simplifications made in the model, which are unavoidable when approximating the impact of vaccination in the real world.

Conclusions: TAK-003 can considerably reduce dengue burden and lead to cost savings in Thailand. These benefits can be maximized by identifying optimal age cohorts for vaccination and adding catch-up programs. Our model can be used to assess the vaccination impact in other dengue-endemic countries.