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Background: Collaborative comparisons and combinations of epidemic models are used as policy-relevant evidence during epidemic outbreaks. In the process of collecting multiple model projections, such collaborations may gain or lose relevant information. Typically, modellers contribute a probabilistic summary at each time-step. We compared this to directly collecting simulated trajectories. We aimed to explore information on key epidemic quantities; ensemble uncertainty; and performance against data, investigating potential to continuously gain information from a single cross-sectional collection of model results., Methods: We compared projections from the European COVID-19 Scenario Modelling Hub. Five teams modelled incidence in Belgium, the Netherlands, and Spain. We compared July 2022 projections by incidence, peaks, and cumulative totals. We created a probabilistic ensemble drawn from all trajectories, and compared to ensembles from a median across each model's quantiles, or a linear opinion pool. We measured the predictive accuracy of individual trajectories against observations, using this in a weighted ensemble. We repeated this sequentially against increasing weeks of observed data. We evaluated these ensembles to reflect performance with varying observed data., Results: By collecting modelled trajectories, we showed policy-relevant epidemic characteristics. Trajectories contained a right-skewed distribution well represented by an ensemble of trajectories or a linear opinion pool, but not models' quantile intervals. Ensembles weighted by performance typically retained the range of plausible incidence over time, and in some cases narrowed this by excluding some epidemic shapes., Conclusions: We observed several information gains from collecting modelled trajectories rather than quantile distributions, including potential for continuously updated information from a single model collection. The value of information gains and losses may vary with each collaborative effort's aims, depending on the needs of projection users. Understanding the differing information potential of methods to collect model projections can support the accuracy, sustainability, and communication of collaborative infectious disease modelling efforts., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Objectives: Incremental cost-effectiveness analyses may inform the optimal choice of healthcare interventions. Nevertheless, for many vaccines, benefits fluctuate with incidence levels over time. Reevaluating a vaccine after it has successfully decreased incidences may eventually cause a disease resurgence if switching to a vaccine with lower indirect benefits. Decisions may successively alternate between vaccines alongside repeated rises and falls in incidence and when indirect effects from historic use are ignored. Our suggested proposal aims to prevent suboptimal decision making., Methods: We used a conceptual model of demand to illustrate alternating decisions between vaccines because of time-varying levels of indirect effects. Similar to the concept of subsidies, we propose internalizing the indirect effects achievable with vaccines. In a case study over 60 years, we simulated a hypothetical 10-year reevaluation of 2 oncogenic human papillomavirus vaccines, of which only 1 protects additionally against anogenital warts., Results: Our case study showed that the vaccine with additional warts protection is initially valued higher than the vaccine without additional warts protection. After 10 years, this differential decreases because of declines in warts incidence, which supports switching to the nonwarts vaccine that causes a warts resurgence eventually. Instead, pricing the indirect effects separately supports continuing with the warts vaccine., Conclusions: Ignoring how the observed incidences depend on the indirect effects achieved with a particular vaccine may lead to repeated changes in vaccines at successive reevaluations, with unintended resurgences, economic inefficiencies, and eroding vaccine confidence. We propose internalizing indirect effects to prevent vaccines falling victim to their own success., (Copyright © 2021 ISPOR–The Professional Society for Health Economics and Outcomes Research. Published by Elsevier Inc. All rights reserved.)

Background: Despite potentially severe and fatal outcomes, recent studies of solid organ transplant (SOT) recipients in Europe suggest that hepatitis E virus (HEV) infection is underdiagnosed, with a prevalence of active infection of up to 4.4%., Objectives: To determine the cost-effectiveness of introducing routine screening for HEV infection in SOT recipients in the UK., Methods: A Markov cohort model was developed to evaluate the cost-utility of 4 HEV screening options over the lifetime of 1000 SOT recipients. The current baseline of nonsystematic testing was compared with annual screening of all patients by polymerase chain reaction (PCR; strategy A) or HEV-antigen (HEV-Ag) detection (strategy B) and selective screening of patients who have a raised alanine aminotransferase (ALT) value by PCR (strategy C) or HEV-Ag (strategy D). The primary outcome was the incremental cost per quality-adjusted life-year (QALY). We adopted the National Health Service (NHS) perspective and discounted future costs and benefits at 3.5%., Results: At a willingness-to-pay of £20 000/QALY gained, systematic screening of SOT patients by any method (strategy A-D) had a high probability (77.9%) of being cost-effective. Among screening strategies, strategy D is optimal and expected to be cost-saving to the NHS; if only PCR testing strategies are considered, then strategy C becomes cost-effective (£660/QALY). These findings were robust against a wide range of sensitivity and scenario analyses., Conclusions: Our model showed that routine screening for HEV in SOT patients is very likely to be cost-effective in the UK, particularly in patients presenting with an abnormal alanine aminotransferase., (Copyright © 2019 ISPOR–The Professional Society for Health Economics and Outcomes Research. Published by Elsevier Inc. All rights reserved.)