OBJECTIVES: The TAK-003 candidate vaccine has been shown to provide long-term efficacy against symptomatic and hospitalized dengue based on data from the DEN-301 trial. The objective of the present study was to assess the disease impact and cost-effectiveness of routine vaccination with two doses of TAK-003 in Thailand.

METHODS: A deterministic compartmental dynamic model of dengue transmission was developed that can explicitly model host and vector populations, seasonality, and up to four serotype-specific dengue infections. Model parameters were either fitted or taken from literature where relevant, and vaccine efficacy was informed by the DEN-301 trial. The model was adapted to Thai epidemiology by fitting to the dengue incidence observed in Thailand over the period 2011-2020 accounting for under-reporting and using Thai-specific input data wherever possible. Routine vaccination of 11-year-olds with TAK-003 was assessed for disease impact and cost-effectiveness over a 20-year time horizon.

RESULTS: Routine vaccination of 11-year-olds with TAK-003 at 87% coverage led to a 41% reduction in symptomatic dengue cases and 50% reduction in hospitalized dengue cases in Thailand, which translated to 155,407 averted disability-adjusted life years (DALYs). Vaccination was cost-saving compared to no vaccination and could lead to savings of 1.42 billion US$ over 20 years (3% discount rate applied) from the societal perspective, including averted direct medical cost (1.37 billion), direct non-medical cost (169 million), productivity loss (483 million) and school absenteeism cost (28 million), while incurring 628 million US$ vaccine-related (acquisition and administration) costs. This compares to cost-savings of 744 million US$ under the payer perspective (direct medical and vaccine-related costs only). Vaccination with TAK-003 remained cost-saving when varying key model parameters.

CONCLUSIONS: Routine vaccination of children aged 11 years with two doses of TAK-003 could lead to significant reductions of symptomatic and hospitalized dengue along with considerable societal and healthcare cost-savings in Thailand.