Exploring challenges and opportunities in meeting late-stage end TB goals: Taiwan as a case study
File(s)
Author(s)
Fu, Han
Type
Thesis
Abstract
Tuberculosis (TB) in intermediate-burden settings presents an annual incidence rate between 10 and 100 per 100,000 population, with burden concentrating in older adults. Although these settings do not comprise a major part of global TB burden, understanding their epidemics can cast light on priorities for TB elimination elsewhere. In this thesis, using Taiwan as a country example, I apply mathematical models to explore the opportunities and challenges for TB control in such settings.
I first evaluate a current policy question about discontinuing universal Bacillus Calmette-Guerin vaccination in Taiwan, considering the vaccine benefits and side-effects. The analysis shows that a substantial cost reduction would occur following the discontinuation, while an uncertain net health impact would result from different assumptions of vaccine protection.
Next, I explore the mechanisms driving a notable feature of the TB epidemic - the concentrated burden in the elderly. A combination effect of ‘immune senescence’, ’declining transmission’, and ’age-specific assortativity’ is most likely to explain the wide age disparities, as well as the declining trend of TB burden. I also discuss further evidence for characterising these mechanisms.
In collaboration with the Taiwan TB programme, I incorporate key risk structures of TB and compare the impacts of potential strategies for meeting the End TB goals. Model projections reveal a limited effect of active case-finding but great potential of preventive therapy in reducing TB burden, with incremental contribution from glycaemic control. Additionally, critical determinants of the epidemiological impacts are evaluated.
Overall, in the intermediate-burden settings like Taiwan, ageing trend will present considerable challenges in achieving TB elimination. Consequently, control strategies which address remote infection in elders will be increasingly crucial. Learnings from this thesis can be useful in strategic planning for other countries approaching similar conditions of TB burden. Meanwhile, uncertainties in TB epidemiology and interventions need further assessment.
I first evaluate a current policy question about discontinuing universal Bacillus Calmette-Guerin vaccination in Taiwan, considering the vaccine benefits and side-effects. The analysis shows that a substantial cost reduction would occur following the discontinuation, while an uncertain net health impact would result from different assumptions of vaccine protection.
Next, I explore the mechanisms driving a notable feature of the TB epidemic - the concentrated burden in the elderly. A combination effect of ‘immune senescence’, ’declining transmission’, and ’age-specific assortativity’ is most likely to explain the wide age disparities, as well as the declining trend of TB burden. I also discuss further evidence for characterising these mechanisms.
In collaboration with the Taiwan TB programme, I incorporate key risk structures of TB and compare the impacts of potential strategies for meeting the End TB goals. Model projections reveal a limited effect of active case-finding but great potential of preventive therapy in reducing TB burden, with incremental contribution from glycaemic control. Additionally, critical determinants of the epidemiological impacts are evaluated.
Overall, in the intermediate-burden settings like Taiwan, ageing trend will present considerable challenges in achieving TB elimination. Consequently, control strategies which address remote infection in elders will be increasingly crucial. Learnings from this thesis can be useful in strategic planning for other countries approaching similar conditions of TB burden. Meanwhile, uncertainties in TB epidemiology and interventions need further assessment.
Version
Open Access
Date Issued
2019-10
Date Awarded
2020-03
Copyright Statement
Creative Commons Attribution NonCommercial Licence
License URL
Advisor
Arinaminpathy, Nimalan
Hallett, Timothy
Sponsor
Imperial College London
Publisher Department
School of Public Health
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)