A multi-country study of dengue vaccination modelling using econometric and GIS approaches in three dengue-endemic countries: Vietnam, Thailand, and Colombia

The overall theme of this thesis is to generate innovative health-economic outcomes which are needed prior to the introduction of population-level dengue immunization programs in three dengue-endemic countries: Vietnam, Thailand, and Colombia. This thesis consists of six chapters which are distinctive but inter-related. Following the introductory chapter, where the existing literature search is carried out, in Chapter 2 I begin by conducting a multi-country study of the economic burden of dengue fever based on standardized field studies in the three dengue-endemic countries. In Chapter 3, an Early Warning Signal (EWS) model is developed based upon climate and non-climate factors. In particular, this chapter adopts a theory of elasticity, which is not common in the field of health economics but which is a key notion in economics, to predict geographically-dispersed dengue outbreaks in Colombia. The econometric technique used in the third chapter is further extended to the mixed-effects modeling work in Chapter 4 where high-risk areas for dengue fever are identified at the 5 km by 5 km geographical unit, and the number of dengue vaccine doses is estimated at the population-level in Vietnam, Thailand, and Colombia. The concepts and methodologies applied in both Chapter 3 and 4 are unconventional but clearly underscore the needs for innovative approaches in order to respond to existing public health problems. Based on the findings from Chapter 1 to Chapter 4, the vaccination impacts and cost-effectiveness of dengue vaccination strategies are estimated in the three dengue-endemic countries in Chapter 5. Vaccination impact is derived from a spatially explicit, individual-based meta-population transmission model developed by the Oxford/Exeter group for the WHO Strategic Advisory Group Experts (SAGE) working group exercise. In addition, country-specific health economic parameters are taken from the economic burden field studies in the second chapter of the thesis. In particular, Chapter 5 is designed to reflect the most up-to-date information on the dengue vaccine development: including controversial debates over CYD-TDV, introducing a new vaccine candidate (NVC) with no safety concern identified in CYD-TDV. Lastly, Chapter 6 summarizes the roles of the four core chapters as a country-specific investment case, and underscores the importance of an evidence-based decision-making process prior to implementing vaccination campaigns at the population-level.