Study 1: Cost-effectiveness of TAK-003 Dengue Vaccination in Thailand This study aims to evaluate the cost-effectiveness of introducing the live-attenuated tetravalent dengue vaccine (TAK-003) into Thailand's national immunization program. The study will compare routine vaccination strategies targeting two high-risk age groups: older children aged 9-14 years and adolescents/young adults aged 15-24 years, to identify the most appropriate target population for national implementation. A model-based economic evaluation will be conducted using a static Markov model combined with a decision tree from a societal perspective. Model parameters will be obtained from published literature, national surveillance databases, healthcare utilization data, and other relevant sources. The model will estimate lifetime health outcomes, healthcare costs, quality-adjusted life years (QALYs), incremental cost-effectiveness ratios (ICERs), and budget impact. Deterministic and probabilistic sensitivity analyses will be performed to assess uncertainty in model parameters. The findings are expected to provide evidence to support policy decisions regarding the inclusion of TAK-003 in Thailand's national immunization program. Study 2: Determinants of Dengue Vaccine Acceptance among Thai Adults and Parents This study aims to examine dengue vaccine acceptance and factors influencing vaccination decisions among Thai adults and parents of children aged 4-18 years. Understanding vaccine acceptance is essential for successful implementation of future dengue vaccination programs in Thailand. This study will employ a sequential explanatory mixed-methods design consisting of two phases. The first phase is a cross-sectional survey conducted among Thai adults and parents attending outpatient clinics at two tertiary hospitals. Participants will complete a structured questionnaire assessing sociodemographic characteristics, dengue-related experiences, psychological antecedents of vaccination using a modified Thai version of the 7Cs model, willingness to pay, and dengue vaccine acceptance. In the second phase, purposively selected participants from the quantitative survey will participate in semi-structured in-depth interviews to explore perceptions, beliefs, attitudes, and contextual factors influencing dengue vaccine decision-making. Quantitative and qualitative findings will be integrated to provide a comprehensive understanding of vaccine acceptance and hesitancy. The findings will provide evidence to inform communication strategies, public health interventions, and policy development aimed at improving dengue vaccine uptake in Thailand.
Study Type
OBSERVATIONAL
Enrollment
350
Thai children age 9-14 and 15-24 years with dengue vaccine
Hospital for Tropical Diseases, Faculty of Tropical Medicine
Bangkok, Thailand
Dengue vaccine hesitancy measured using the 7C-model
Dengue vaccine hesitancy will be assessed using an adapted version of the validated 7C Model of Vaccine Readiness questionnaire. The questionnaire will be adapted to the context of dengue vaccination while retaining the seven psychological antecedents of vaccination: Confidence, Complacency, Constraints, Calculation, Collective Responsibility, Compliance, and Conspiracy. Scoring of the 7C model: Each item was rated on a 7-point Likert scale from 1 to 7. For each 7C domain, the mean score of its constituent items was calculated, resulting in a domain score ranging from 1 to 7. A higher score indicated greater vaccine hesitancy. Items were reverse-scored where necessary so that the direction of all domain scores was consistent, with higher scores representing greater vaccine hesitancy.
Time frame: 1 year
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