Panovska-Griffiths, J. | Search bioRxiv

bioRxiv2019

Exploring the role of mass immunisation in influenza pandemic preparedness: a modelling study for the UK context

Existing modelling work on preparedness to pandemic influenza has focused on evaluating specific countermeasures for pandemics with specific characteristics (typically based on historical instances). The aim of this study was to inform policy on preparedness planning for pandemic influenza based on the assessment of a wide range of scenarios and free from restrictive assumptions about timing and features of the next pandemic.\n\nWe carried out epidemiological modelling and health economic analysis of an extensive set of scenarios, each comprising a combination of pandemic, vaccine and immunisation programme characteristics in presence or absence of access to effective antivirals. Preparedness policies that incorporate mass immunisation were evaluated on the basis of there being a given chance of a pandemic each year. To support understanding and exploration of model output, an interactive visualisation tool was devised and made available online.\n\nWe evaluated over 29 million combinations of pandemic and policy characteristics. Preparedness plans incorporating mass immunisation show positive net present value for a wide range of pandemic scenarios, predominantly in the absence of effective antivirals. Plans based on the responsive purchase of vaccine have greater benefit than plans reliant on the purchase and maintenance of a stockpile if immunisation can start without extensive delays. This finding is not dependent on responsively purchased vaccine being more effective than stockpiled vaccine, but rather is driven by avoiding the costs of storing and replenishing a stockpile.\n\nWhile emerging technologies for rapid vaccine development and production increase the prospects for mass immunisation to be an effective countermeasure, policies based on the responsive purchase of vaccine not tailored to the pandemic should be explored. Focus is also required on the pandemic intelligence, decision, contractual and logistical processes on which timely commencement of immunisation in a pandemic is reliant.

systems biology↗

bioRxiv2018

Estimates for quality of life loss due to RSV

A number of vaccines against Respiratory Syncytial Virus (RSV) infection are approaching licensure. Deciding which RSV vaccine strategy, if any, to introduce, will partly depend on cost-effectiveness analyses, which compares the relative costs and health benefits of a potential vaccination programme. Health benefits are usually measured in Quality Adjusted Life Year (QALY) loss, however, there are no QALY loss estimates for RSV that have been determined using standardised instruments. Moreover, in children under the age of five years in whom severe RSV episodes predominantly occur, there are no appropriate standardised instruments to estimate QALY loss. We estimated the QALY loss due to RSV across all ages by developing a novel regression model which predicts the QALY loss without the use of standardised instruments. To do this, we conducted a surveillance study which targeted confirmed episodes in children under the age of five years (confirmed cases) and their household members who experienced symptoms of RSV during the same time (suspected cases.) All participants were asked to complete questions regarding their health during the infection, with the suspected cases aged 5-14 and 15+ years old additionally providing Health-Related Quality of Life (HR-QoL) loss estimates through completing EQ-5D-3L-Y and EQ-5D-3L instruments respectively. The questionnaire responses from the suspected cases were used to calibrate the regression model. The calibrated regression model then used other questionnaire responses to predict the HR-QoL loss without the use of EQ-5D instruments. The age-specific QALY loss was then calculated by multiplying the HR-QoL loss on the worst day predicted from the regression model, with estimates for the duration of infection from the questionnaires and a scaling factoring for disease severity. Our regression model for predicting HR-QoL loss estimates that for the worst day of infection, suspected RSV cases in persons five years and older who do and do not seek healthcare have an HR-QoL loss of 0{middle dot}616 (95% CI 0{middle dot}155-1{middle dot}371) and 0{middle dot}405 (95% CI 0{middle dot}111-1{middle dot}137) respectively. This leads to a QALY loss per RSV episode of 1{middle dot}950 x 10-3 (95% CI 0{middle dot}185 x 10-3 -9{middle dot}578 x 10-3) and 1{middle dot}543 x 10-3 (95% CI 0{middle dot}136 x 10-3 -6{middle dot}406 x 10-3) respectively. For confirmed cases in a child under the age of five years who sought healthcare, our model predicted a HR-QoL loss on the worst day of infection of 0{middle dot}820 (95% CI 0{middle dot}222-1{middle dot}450) resulting in a QALY loss per RSV episode of 3{middle dot}823 x 10-3 (95% CI 0{middle dot}492 x 10-3 -12{middle dot}766 x 10-3). Combing these results with previous estimates of RSV burden in the UK, we estimate the annual QALY loss of healthcare seeking RSV episodes as 1,199 for individuals aged five years and over and 1,441 for individuals under five years old. The QALY loss due to an RSV episode is less than the QALY loss due to an Influenza episode. These results have important implications for potential RSV vaccination programmes, which has so far focused on preventing infections in infants--where the highest reported disease burden lies. Future potential RSV vaccination programmes should also evaluate their impact on older children and adults, where there is a substantial but unsurveilled QALY loss.

epidemiology↗