Article: Understanding the Cost-Effectiveness of Influenza Vaccination in Children: Methodological Choices and Seasonal Variability.[show abstract] [hide abstract]
ABSTRACT: BACKGROUND: The universal vaccination of children for influenza has recently been recommended in the UK and is being considered in other developed countries. OBJECTIVES: The aim of this study was to explore the potential costs and benefits of childhood influenza vaccination to gain a better understanding of the key drivers of cost-effectiveness. METHODS: As our case study we examined the cost-effectiveness of vaccination in Australian schoolchildren using an age-stratified Susceptible Exposed Infectious Recovered model. RESULTS: The results of this study highlight the critical role that methodological choices play in determining the cost-effectiveness of influenza vaccination. These choices include decisions about the structure of the model (including/excluding herd immunity) and what costs and benefits to include in the analysis. In scenarios where herd protection was included we estimated that the program was likely to be cost-effective. The study also illustrates the importance of the inherent seasonal variability of influenza, which can produce counter-intuitive results, with low transmission seasons being easier to control by vaccination but resulting in fewer benefits. CONCLUSIONS: Universal childhood influenza vaccination is likely to be cost-effective if a substantial herd protection effect can be achieved by the program. However, it is important that decision makers understand the role of seasonal variability and the impact of alternative methodological choices in economic evaluations of influenza vaccination.PharmacoEconomics 05/2013; · 2.66 Impact Factor
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ABSTRACT: Dengue is the world's major arbovirosis and therefore an important public health concern in endemic areas. The availability of weekly reports of dengue cases in Singapore offers the opportunity to analyze the transmission dynamics and the impact of vector control strategies. Based on a previous model studying the impact of vector control strategies in Singapore during the 2005 outbreak, a simple vector-host model accounting for seasonal fluctuation in vector density was developed to estimate the parameters governing the vector population dynamics using dengue fever incidence data from August 2003 to December 2007. The impact of vector control, which consisted principally of a systematic removal of actual and potential breeding sites during a six-week period in 2005, was also investigated. Although our approach does not account for the complex life cycle of the vector, the good fit between data and model outputs showed that the impact of seasonality on the transmission dynamics is highly important. Moreover, the periodic fluctuations of the vector population were found in phase with temperature variations, suggesting a strong climate effect on the vector density and, in turn, on the transmission dynamics.Mathematical biosciences 04/2013; · 1.30 Impact Factor
Article: Key issues for estimating the impact and cost-effectiveness of seasonal influenza vaccination strategies.[show abstract] [hide abstract]
ABSTRACT: Many countries have considered or are considering modifying their seasonal influenza immunization policies. Estimating the impact of such changes requires understanding the existing clinical and economic burden of influenza, as well as the potential impact of different vaccination options. Previous studies suggest that vaccinating clinical risk groups, health care workers, children and the elderly may be cost-effective. However, challenges in such estimation include: (1) potential cases are not usually virologically tested; (2) cases have non-specific symptoms and are rarely reported to surveillance systems; (3) endpoints for influenza proxies (such as influenza-like illness) need to be matched to case definitions for treatment costs, (4) disease burden estimates vary from year to year with strain transmissibility, virulence and prior immunity, (5) methods to estimate productivity losses due to influenza vary, (6) vaccine efficacy estimates from trials differ due to variation in subtype prevalence, vaccine match and case ascertainment, and (7) indirect (herd) protection from vaccination depends on setting-specific variables that are difficult to directly measure. Given the importance of knowing the impact of changes to influenza policy, such complexities need careful treatment using tools such as population-based trial designs, meta-analyses, time-series analyses and transmission dynamic models.Human vaccines & immunotherapeutics. 01/2013; 9(5).
Article: Childhood varicella-zoster virus vaccination in Belgium: Cost-effective only in the long run or without exogenous boosting?[show abstract] [hide abstract]
ABSTRACT: Aim: To assess the effectiveness and cost-effectiveness of a universal childhood varicella-zoster vaccination programme in Belgium (1) using the most recent Belgian data on varicella-zoster burden, (2) exploring different options for the timing of the second dose, (3) obtaining results with and without exogenous natural boosting, and (4) investigating the possible additional benefit of zoster booster vaccination for adults at age 50 or 60 years. Methods: An extensively studied and improved dynamic model is used to estimate primary and breakthrough chickenpox and zoster cases over time. For a range of vaccination options, we compared the direct costs (health care payer perspective) and health outcomes (including Quality-Adjusted Life-Years (QALYs) lost) associated with chickenpox and herpes zoster. Estimates of social contact patterns, health care use, costs and QALY losses are almost exclusively based on Belgian databases and surveys. Results and Conclusions: If exogenous natural boosting exists, a net loss in QALYs is expected for several decades after implementing a universal chickenpox vaccination programme, due to an increase in zoster mainly in persons aged 50-80 years. This result holds also for scenarios that minimise or counteract the expected increase in zoster incidence (e.g. additional booster vaccinations in adults). However, if the boosting hypothesis is not true or if costs and QALYs are cumulated over at least 33 to more than 100 years after vaccination (depending on the assumptions made), different options for universal 2-dose vaccination against chickenpox in Belgium would be cost-effective at a vaccine price of €43/dose or lower.Human vaccines & immunotherapeutics. 01/2013; 9(4).
Article: Public preferences over efficiency, equity and autonomy in vaccination policy: An empirical study.[show abstract] [hide abstract]
ABSTRACT: Vaccination programs increasingly have to comply with standards of evidence-based decision making. However, such a framework tends to ignore social and ethical sensitivities, risking policy choices that lack crucial public support. Research is needed under which circumstances and to which extent equity and autonomy should prevail over effectiveness and cost-effectiveness in matters of infectious disease prevention. We report on a study investigating public preferences over various vaccination policy options, based on a population survey held in Flanders, Belgium (N = 1049) between March and July 2011. We found (1) that public support varied considerably between policies that were equally efficient in preventing disease but differed according to target group or incentives to improve uptake and (2) that preferences over the use of legal compulsion, financial accountability or the offering of rewards appear to be driven by individuals' social orientation.Social Science [?] Medicine 11/2012; · 2.70 Impact Factor