Haemophilus influenzae type b vaccine in low- and middle- income countries: Impact, costs and incremental cost-utility.

Haemophilus influenzae type b (Hib) is an infectious bacterium transmitted from person to person through close contact. Hib can cause meningitis, pneumonia and a number of rarer forms of disease, primarily in children less than five years. Hib conjugate vaccines became available during the early 1990s and high-income countries quickly introduced this vaccine into their routine programmes and have now achieved a near disappearance of Hib disease. However, relatively high vaccine prices and uncertainties about Hib disease burden led to a slow uptake in low- and middle-income countries. The aim of this PhD is to fill gaps in knowledge about the value of Hib vaccination, in terms of whether or not it is a cost-effective intervention in low- and middle-income countries. Moreover, since economic evaluation involves gathering evidence about numerous criteria that may be considered in isolation by policy makers, such as vaccine efficacy, disease burden, meningitis sequelae prevalence and cold chain expansion costs, specific objectives are also to address some of the unanswered questions about key inputs and determinants of cost-effectiveness. The framework of the PhD is shaped around a decision-analytic model designed to estimate the cost-utility of Hib vaccination. The methodology, collection and analysis of data inputs needed to populate the model represent a number of sub-studies, which are all contributions to new evidence. These include a meta-analysis of Hib vaccine efficacy, calculation of Disability Adjusted Life Years due to Hib disease, estimation of treatment costs of Hib disease, assessment of productivity costs due to meningitis sequelae, and calculation of systems costs of introducing Hib vaccine. Case studies from two countries are included in the sub-studies; productivity costs of meningitis sequelae are investigated in Senegal and systems costs of Hib vaccine introduction are estimated in Ethiopia. Cost-utility results generated from the decision-analytic model are presented for two low-income countries; India and Uzbekistan, and one middle-income country; Belarus. This PhD thesis is the first attempt to combine evidence on disease burden, costs and impact of Hib vaccine across multiple countries using a consistent framework and comparable input parameters. As a result, new insights into the relative cost-utility in countries with different economic and epidemiological circumstances are obtained.