Seven challenges for model-driven data collection in experimental and observational studies

Infectious disease models are both concise statements of hypotheses and powerful techniques for creating tools from hypotheses and theories. As such, they have tremendous potential for guiding data collection in experimental and observational studies, leading to more efficient testing of hypotheses and more robust study designs. In numerous instances, infectious disease models have played a key role in informing data collection, including the Garki project studying malaria, the response to the 2009 pandemic of H1N1 influenza in the United Kingdom and studies of T-cell immunodynamics in mammals. However, such synergies remain the exception rather than the rule; and a close marriage of dynamic modeling and empirical data collection is far from the norm in infectious disease research. Overcoming the challenges to using models to inform data collection has the potential to accelerate innovation and to improve practice in how we deal with infectious disease threats

A motif-based approach to network epidemics

Networks have become an indispensable tool in modelling infectious diseases, with the structure of epidemiologically relevant contacts known to affect both the dynamics of the infection process and the efficacy of intervention strategies. One of the key reasons for this is the presence of clustering in contact networks, which is typically analysed in terms of prevalence of triangles in the network. We present a more general approach, based on the prevalence of different four-motifs, in the context of ODE approximations to network dynamics. This is shown to outperform existing models for a range of small world networks

The social contact hypothesis under the assumption of endemic equilibrium: Elucidating the transmission potential of VZV in Europe.

The basic reproduction number R0 and the effective reproduction number R are pivotal parameters in infectious disease epidemiology, quantifying the transmission potential of an infection in a population. We estimate both parameters from 13 pre-vaccination serological data sets on varicella zoster virus (VZV) in 12 European countries and from population-based social contact surveys under the commonly made assumptions of endemic and demographic equilibrium. The fit to the serology is evaluated using the inferred effective reproduction number R as a model eligibility criterion combined with AIC as a model selection criterion. For only 2 out of 12 countries, the common choice of a constant proportionality factor is sufficient to provide a good fit to the seroprevalence data. For the other countries, an age-specific proportionality factor provides a better fit, assuming physical contacts lasting longer than 15 min are a good proxy for potential varicella transmission events. In all countries, primary infection with VZV most often occurs in early childhood, but there is substantial variation in transmission potential with R0 ranging from 2.8 in England and Wales to 7.6 in The Netherlands. Two non-parametric methods, the maximal information coefficient (MIC) and a random forest approach, are used to explain these differences in R0 in terms of relevant country-specific characteristics. Our results suggest an association with three general factors: inequality in wealth, infant vaccination coverage and child care attendance. This illustrates the need to consider fundamental differences between European countries when formulating and parameterizing infectious disease models

Partially wrong? Partial equilibrium and the economic analysis of public health emergencies of international concern

Parieu Marie-Louis-Pierre Félix Esquirou de. Nomination des inspecteurs de l'instruction primaire. In: Bulletin administratif de l'instruction publique. Tome 1 n°11, novembre 1850. pp. 371-389

Estimating the cost-effectiveness of vaccination against herpes zoster in England and Wales

A live-attenuated vaccine against herpes zoster (HZ) has been approved for use, on the basis of a large-scale clinical trial that suggests that the vaccine is safe and efficacious. This study uses a Markov cohort model to estimate whether routine vaccination of the elderly (60+) would be cost-effective, when compared with other uses of health care resources. Vaccine efficacy parameters are estimated by fitting a model to clinical trial data. Estimates of QALY losses due to acute HZ and post-herpetic neuralgia were derived by fitting models to data on the duration of pain by severity and the QoL detriment associated with different severity categories, as reported in a number of different studies. Other parameters (such as cost and incidence estimates) were based on the literature, or UK data sources. The results suggest that vaccination of 65 year olds is likely to be cost-effective (base-case ICER=pound20,400 per QALY gained). If the vaccine does offer additional protection against either the severity of disease or the likelihood of developing PHN (as suggested by the clinical trial), then vaccination of all elderly age groups is highly likely to be deemed cost-effective. Vaccination at either 65 or 70 years (depending on assumptions of the vaccine action) is most cost-effective. Including a booster dose at a later age is unlikely to be cost-effective

Cost-effectiveness of varicella and zoster vaccination in England & Wales : importance measures for correlated parameters

AbstractThis study aims to explore irregular relationships between input and outcomes in cost-effectiveness analysis, accounting for interdependencies between many input parameters. We used a dynamic infectious disease transmission model investigating the cost-effectiveness of varicella and zoster vaccination as a case study. Incremental costs and effects were used separately as the outcomes of interest, rather than the ratio between these, and a single R2 was calculated for groups of interdependent input parameters. Partial R2 was obtained as measure for the marginal proportion of variance explained. The most important input parameters were related to zoster epidemiology and disease transmission. In case of linear relationships, R2 is an easy to obtain importance measure, also in the presence of interdependent input parameters