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Optimising age coverage of seasonal influenza vaccination in England: A mathematical and health economic evaluation.

ABSTRACT: For infectious disease prevention, policy-makers are typically required to base policy decisions in light of operational and monetary restrictions, prohibiting implementation of all candidate interventions. To inform the evidence-base underpinning policy decision making, mathematical and health economic modelling can be a valuable constituent. Applied to England, this study aims to identify the optimal target age groups when extending a seasonal influenza vaccination programme of at-risk individuals to those individuals at low risk of developing complications following infection. To perform this analysis, we utilise an age- and strain-structured transmission model that includes immunity propagation mechanisms which link prior season epidemiological outcomes to immunity at the beginning of the following season. Making use of surveillance data from the past decade in conjunction with our dynamic model, we simulate transmission dynamics of seasonal influenza in England from 2012 to 2018. We infer that modified susceptibility due to natural infection in the previous influenza season is the only immunity propagation mechanism to deliver a non-negligible impact on the transmission dynamics. Further, we discerned case ascertainment to be higher for young infants compared to adults under 65 years old, and uncovered a decrease in case ascertainment as age increased from 65 to 85 years of age. Our health economic appraisal sweeps vaccination age space to determine threshold vaccine dose prices achieving cost-effectiveness under differing paired strategies. In particular, we model offering vaccination to all those low-risk individuals younger than a given age (but no younger than two years old) and all low-risk individuals older than a given age, while maintaining vaccination of at-risk individuals of any age. All posited strategies were deemed cost-effective. In general, the addition of low-risk vaccination programmes whose coverage encompassed children and young adults (aged 20 and below) were highly cost-effective. The inclusion of elder age-groups to the low-risk programme typically lessened the cost-effectiveness. Notably, elderly-centric programmes vaccinating from 65-75 years and above had the least permitted expense per vaccine.

SUBMITTER: Hill EM

PROVIDER: S-EPMC7567368 | biostudies-literature | 2020 Oct

REPOSITORIES: biostudies-literature

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Optimising age coverage of seasonal influenza vaccination in England: A mathematical and health economic evaluation.

Hill Edward M EM Petrou Stavros S Forster Henry H de Lusignan Simon S Yonova Ivelina I Keeling Matt J MJ

PLoS computational biology 20201006 10

For infectious disease prevention, policy-makers are typically required to base policy decisions in light of operational and monetary restrictions, prohibiting implementation of all candidate interventions. To inform the evidence-base underpinning policy decision making, mathematical and health economic modelling can be a valuable constituent. Applied to England, this study aims to identify the optimal target age groups when extending a seasonal influenza vaccination programme of at-risk individ ...[more]

PMID: 33021983

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Project description:BackgroundThere is substantial burden of seasonal influenza in Kenya, which led the government to consider introducing a national influenza vaccination programme. Given the cost implications of a nationwide programme, local economic evaluation data are needed to inform policy on the design and benefits of influenza vaccination. We set out to estimate the cost-effectiveness of seasonal influenza vaccination in Kenya.MethodsWe fitted an age-stratified dynamic transmission model to active surveillance data from patients with influenza from 2010 to 2018. Using a societal perspective, we developed a decision tree cost-effectiveness model and estimated the incremental cost-effectiveness ratio (ICER) per disability-adjusted life year (DALY) averted for three vaccine target groups: children 6-23 months (strategy I), 2-5 years (strategy II) and 6-14 years (strategy III) with either the Southern Hemisphere influenza vaccine (Strategy A) or Northern Hemisphere vaccine (Strategy B) or both (Strategy C: twice yearly vaccination campaigns, or Strategy D: year-round vaccination campaigns). We assessed cost-effectiveness by calculating incremental net monetary benefits (INMB) using a willingness-to-pay (WTP) threshold of 1-51% of the annual gross domestic product per capita ($17-$872).ResultsThe mean number of infections across all ages was 2-15 million per year. When vaccination was well timed to influenza activity, the annual mean ICER per DALY averted for vaccinating children 6-23 months ranged between $749 and $1385 for strategy IA, $442 and $1877 for strategy IB, $678 and $4106 for strategy IC and $1147 and $7933 for strategy ID. For children 2-5 years, it ranged between $945 and $1573 for strategy IIA, $563 and $1869 for strategy IIB, $662 and $4085 for strategy IIC, and $1169 and $7897 for strategy IID. For children 6-14 years, it ranged between $923 and $3116 for strategy IIIA, $1005 and $2223 for strategy IIIB, $883 and $4727 for strategy IIIC and $1467 and $6813 for strategy IIID. Overall, no vaccination strategy was cost-effective at the minimum ($17) and median ($445) WTP thresholds. Vaccinating children 6-23 months once a year had the highest mean INMB value at $872 (WTP threshold upper limit); however, this strategy had very low probability of the highest net benefit.ConclusionVaccinating children 6-23 months once a year was the most favourable vaccination option; however, the strategy is unlikely to be cost-effective given the current WTP thresholds.

Project description:INTRODUCTION:Influenza is a major cause of morbidity and mortality among adults. The most effective strategy for preventing influenza is annual vaccination. However, vaccination coverage has been suboptimal among adult populations. The purpose of this study is to assess trends in influenza vaccination among adult populations. METHODS:Data from the 2010-2016 National Health Interview Survey were analyzed in 2018 to estimate vaccination coverage during the 2010-2011 through 2015-2016 seasons. Trends of vaccination in recent years were assessed. Vaccination coverage by race/ethnicity within each group was examined. Multivariable logistic regression and predictive marginal models were conducted to identify factors associated with vaccination, and interactions between race/ethnicity and other demographic and access-to-care characteristics were assessed. RESULTS:Vaccination coverage among adults aged ?18 years increased from 38.3% in the 2010-2011 season to 43.4% in the 2015-2016 season, with an average increase of 1.3 percentage points annually. From the 2010-2011 through 2015-2016 seasons, coverage was stable for adults aged ?65 years and changed by -0.1 to 9.9 percentage points for all other examined subgroups. Coverage in 2015-2016 was 70.4% for adults aged ?65 years, 46.4% for those aged 50-64 years, and 32.3% for those aged 18-49 years; 47.9% for people aged 18-64 years with high-risk conditions; 64.8% for healthcare personnel; and 50.3% for pregnant women. Among adults aged ?18 years for the 2015-2016 season, coverage was significantly lower among non-Hispanic blacks and Hispanics compared with non-Hispanic whites. CONCLUSIONS:Overall, influenza vaccination coverage among adults aged ?18 years increased during 2010-2016, but it remained below the national target of 70%. Vaccination coverage varied by age, risk status, race/ethnicity, healthcare personnel, and pregnancy status. Targeted efforts are needed to improve coverage and reduce disparities.

Project description:BackgroundA number of cost-effectiveness analysis of influenza vaccination have been conducted to estimate value of influenza vaccines in elderly and health workers (HWs). This study aims to summarize cost-effectiveness evidence by pooling the incremental net monetary benefit (INMB) of influenza vaccination.MethodsA systematic review was performed in electronic databases from their inceptions to February 2022. Cost-effectiveness studies reporting quality-adjusted life year (QALY), or life year (LY) of influenza vaccination were included. Stratified meta-analyses by population, perspective, country income-level, and herd-effect were performed to pool INMB across studies. The protocol was registered at PROSPERO (CRD42021246746).FindingsA total of 21 studies were included. Eighteen studies were conducted in elderly, two studies were conducted in HWs, and one study was conducted in both elderly and HWs. According to pre-specified analyses, studies for elderly in high-income economies (countries) (HIEs) and upper-middle income economies (UMIEs) without herd effect could be pooled. For HIEs under a societal perspective, the perspective which identify all relevant costs occurred in the society including direct medical cost, direct non-medical cost and indirect cost, pooled INMB was $217·38 (206·23, 228·53, I2 =28.2%), while that for healthcare provider/payer perspective was $0·20 (-11,908·67, 11,909·07, I2 = 0.0%). For societal perspective in UMIEs, pooled INMB was $28·39 (-190·65, 133·87, I2 = 92.8%). The findings were robust across a series of sensitivity analyses for HIEs. Studies in HWs indicated that influenza vaccination was cost-effective compared to no vaccination or current practice.InterpretationInfluenza vaccination might be cost-effective for HWs and elderly in HIEs under a societal perspective with relatively small variations among included studies, while there remains limited evidence for healthcare provider/payer perspective or other level of incomes. Further evidence is warranted.FundingThis study was funded by a grant of Immunization, Vaccine and Biologicals department of the World Health Organization. The authors would like to acknowledge the contributions of the US CDC which provided financial support to the development and publication of this report. Grant number US CDC, WHO IVR (U50CK000431).

Project description:ImportanceTimely identification of patients likely to miss seasonal influenza vaccination (SIV) could help health care practitioners tailor services and gain efficiency.ObjectiveTo develop and validate a predictive model of SIV uptake among at-risk adults.Design, setting, and participantsThis prognostic study constructed a prediction model for vaccine uptake by adults at increased risk of influenza-associated complications. Drawing from the Clinical Practice Research Datalink database's records of primary care data of 324 284 adults routinely collected at general practices across England from January 2011 to December 2016, logistic regression models were trained on data from patients registered from January 2012 to December 2013 and validated with out-of-sample data from patients registered from January 2015 to December 2016. Data were extracted from the database December 2018 and analyzed between September 2019 and December 2019.ExposuresCovariates included sex, age, race/ethnicity, smoking status, socioeconomic status, previous pneumococcal vaccination, prior season SIV uptake, and clinical risk conditions.Main outcomes and measuresThe main outcome was patient-level SIV uptake. Model performance was measured via misclassification rate, Brier score, sensitivity, specificity, and area under the curve.ResultsThe training data sets consisted of 324 284 (aged 18 to 64 years) and 186 426 (aged 65 years or older) patients. The mean (SD) age in the training data among patients aged 18 to 64 years was 45 (13) years; 161 487 (49.8%) were women, and 102 133 (31.5%) were categorized as white. Among patients aged 65 years or older, the mean (SD) age was 77 (8) years; 96 169 (51.6%) were women, and 64 996 (34.9%) were categorized as white. The validation data sets consisted of 35 210 patients aged 18 to 64 years and 25 497 aged 65 years or older. The mean (SD) age in the validation data set among patients aged 18 to 64 years was 42 (14) years; 17 296 (49.1%) were women, and 13 346 (37.9%) were categorized as white. Among patients aged 65 years or older, the mean (SD) age was 73 (8) years; 13 135 (51.5%) were women, and 9641 (37.8) were categorized as white. Among patients aged 18 to 64 years, SIV uptake was 35.9% (95% CI, 35.7%-36.0%) and 32.6% (95% CI, 32.1%-33.1%) for the training and validation data sets, respectively. Among patients aged 65 years or older, SIV uptake was 83.1% (95% CI, 82.9%-83.2%) and 76.1% (95% CI, 75.5%-76.6%) for the training and validation data sets, respectively. Prior season SIV uptake and pneumococcal vaccination status were the best predictors of SIV uptake. Predicted SIV uptake probabilities for patients aged 18 to 64 years were reliable, but biased toward underpredicting, whereas, among patients aged 65 years or older, they were variable and biased toward overpredicting. Briefly, in out-of-sample validation among patients aged 18 to 64 years, misclassification rates were 0.163 to 0.164, Brier scores were 0.124 to 0.125, area under the receiver operating characteristic curve values ranged from 0.876 to 0.877, sensitivity ranged from 0.705 to 0.720, and specificity ranged from 0.896 to 0.902. In patients aged 65 years or older, misclassification rates were 0.120 to 0.125, Brier scores were 0.0953 to 0.0959, area under the receiver operating characteristic curve was 0.877, sensitivity ranged from 0.919 to 0.936, and specificity ranged from 0.680 to 0.753.Conclusions and relevanceThis study suggests that data obtained from primary care records could accurately predict SIV uptake among at-risk adults. Further research is needed to assess the feasibility and efficacy of implementing this model in clinical settings.

Project description:Backgroundseasonal influenza in nursing homes is a major public health concern, since in EU 43,000 long term care (LTC) facilities host an estimated 2.9 million elderly residents. Despite specific vaccination campaigns, many outbreaks in such institutions are occasionally reported. We explored the dynamics of seasonal influenza starting from real data collected from a nursing home located in Italy and a mathematical model. Our aim was to identify the best vaccination strategy to minimize cases (and subsequent complications) among the guests.Materials and methodsafter producing the contact matrices with surveys of both the health care workers (HCW) and the guests, we developed a mathematical model of the disease. The model consists of a classical SEIR part describing the spreading of the influenza in the general population and a stochastic agent based model that formalizes the dynamics of the disease inside the institution. After a model fit of a baseline scenario, we explored the impact of varying the HCW and guests parameters (vaccine uptake and vaccine efficacy) on the guest attack rates (AR) of the nursing home.Resultsthe aggregate AR of influenza like illness in the nursing home was 36.4% (ward1 = 56%, ward2 = 33.3%, ward3 = 31.7%, ward4 = 34.5%). The model fit to data returned a probability of infection of the causal contact of 0.3 and of the shift change contact of 0.2. We noticed no decreasing or increasing AR trend when varying the HCW vaccine uptake and efficacy parameters, whereas the increase in both guests vaccine efficacy and uptake parameter was accompanied by a slight decrease in AR of all the wards of the LTC facility.Conclusionfrom our findings we can conclude that a nursing home is still an environment at high risk of influenza transmission but the shift change room and the handover situation carry no higher relative risk. Therefore, additional preventive measures in this circumstance may be unnecessary. In a closed environment such as a LTC facility, the vaccination of guests, rather than HCWs, may still represent the cornerstone of an effective preventive strategy. Finally, we think that the extensive inclusion of real life data into mathematical models is promising and may represent a starting point for further applications of this methodology.

Dataset Information

Optimising age coverage of seasonal influenza vaccination in England: A mathematical and health economic evaluation.

Publications

Optimising age coverage of seasonal influenza vaccination in England: A mathematical and health economic evaluation.

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