The cost-effectiveness of influenza vaccination of healthy adults 50–64 years of age

Cost-effectiveness of the adjuvanted quadrivalent influenza vaccine for older adults in South Korea

South Korea's National Immunization Program administers the quadrivalent influenza vaccine (QIV) to manage seasonal influenza, with a particular focus on the elderly. After reviewing the safety and immune response triggered by the adjuvanted QIV (aQIV) in individuals aged 65 and older, the Ministry of Food and Drug Safety in Korea approved its use. However, the extensive impact of aQIV on public health is yet to be fully understood. This study assessed the cost-effectiveness of replacing QIV with aQIV in South Korean adults aged 65 years and older. A dynamic transmission model, calibrated with national influenza data, was applied to compare the influence of aQIV and QIV on older adults and the broader population throughout a single influenza season. This study considered both the direct and indirect effects of vaccination on the elderly. We derived the incremental cost-effectiveness ratios (ICERs) from quality-adjusted life-years (QALYs) and costs incurred, validated through a probabilistic sensitivity analysis with 5,000 simulations. Findings suggest that transitioning to aQIV from QIV in the elderly would be cost-effective, particularly if aQIV's efficacy reaches or exceeds 56.1%. With an ICER of $29,267/QALY, considerably lower than the $34,998/QALY willingness-to-pay threshold, aQIV presents as a cost-effective option. Thus, implementing aQIV with at least 56.1% efficacy is beneficial from both financial and public health perspectives in mitigating seasonal influenza in South Korea.

Cost-Effectiveness of Baloxavir Marboxil Versus Oseltamivir or no Treatment for the Management of Influenza in the United States

INTRODUCTION

This study sought to evaluate the cost-effectiveness of baloxavir marboxil compared with oseltamivir or no antiviral treatment from a US payer perspective using data from a real-world US administrative claims study. Given baloxavir's ability to rapidly stop viral shedding, the potential health economic implications of a baloxavir-induced population-level reduction in viral transmission was also explored.

METHODS

A decision tree cost-effectiveness model was developed for seasonal influenza (2018-2020) using a lifetime time horizon with 3.0% discounting for costs and quality-adjusted life-years (QALYs). Patients aged ≥ 12 years could receive baloxavir, oseltamivir or no antiviral treatment. Patient characteristics, complications, and costs were derived from the Merative™ MarketScan® Research Databases including US commercial claims and Medicare and Medicaid Supplemental databases. A scenario analysis explored the impact of reduced viral transmission with baloxavir.

RESULTS

In the base case analysis, baloxavir was cost-effective within a willingness-to-pay threshold of US$100,000/QALY compared with oseltamivir [incremental cost-effectiveness ratio (ICER), $6813/QALY gained] or no antiviral treatment (ICER, $669/QALY gained). The net monetary benefit (NMB) of baloxavir was $1180 and $6208 compared with oseltamivir and no treatment, respectively. The NMB of baloxavir increased linearly with reductions in viral transmission, where a 5% transmission reduction yielded an NMB of $2592 versus oseltamivir and $7621 versus no treatment. Baloxavir became dominant (more effective and less costly, with ICERs < 0) starting with a 12.0% reduction in viral transmission versus oseltamivir and 6.0% versus no antiviral treatment.

CONCLUSION

Baloxavir was cost-effective compared with oseltamivir or no antiviral treatment. The potential of baloxavir to reduce viral transmission offers a substantial economic benefit from a US payer perspective.

Estimating the impact of influenza vaccination of low-risk 50-64-year-olds on acute and ICU hospital bed usage in an influenza season under endemic COVID-19 in the UK

Co-circulation of influenza and SARS-CoV-2 has the potential to place considerable strain on health-care services. We estimate the cost-effectiveness and health-care resource utilization impacts of influenza vaccination of low-risk 50-64-y-olds in the United Kingdom (UK) against a background SARS-CoV-2 circulation. A dynamic susceptible-exposed-infected-recovered model was used to simulate influenza transmission, with varying rates of vaccine coverage in the low-risk 50-64 y age-group. Four scenarios were evaluated: no vaccination (baseline), 40%, 50%, and 60% coverage. For the 50% and 60% coverage, this rate was also applied to high-risk 50-64-y-olds, whereas 48.6% was used for the baseline and 40% coverage scenarios. Cost-effectiveness was estimated in terms of humanistic outcomes and incremental cost-effectiveness ratio (ICER), with discounting applied at 3%. Overall, influenza vaccination of 50-64-y-olds resulted in reductions in GP visits, hospitalizations, and deaths, with a reduction in influenza-related mortality of 34%, 41%, and 52% for 40%, 50%, and 60% coverage, respectively. All four scenarios resulted in acute and intensive care unit (ICU) bed occupancy levels above available capacity, although vaccination of low-risk 50-64-y-olds resulted in a 35-54% and 16-25% decrease in excess acute and ICU bed requirements, respectively. Vaccination of this group against influenza was highly cost-effective from the payer perspective, with ICERs of £2,200-£2,343/quality-adjusted life year across the coverage rates evaluated. In conclusion, in the UK, vaccination of low-risk 50-64-y-olds against influenza is cost-effective and can aid in alleviating bed shortages in a situation where influenza and SARS-CoV-2 are co-circulating.

The burden of influenza and the role of influenza vaccination in adults aged 50-64 years: A summary of available evidence

Influenza is a vaccine-preventable disease and a global public health problem. Although most national influenza vaccination recommendations focus on subjects aged ≥65 years, an extensive burden of influenza has also been reported in those aged ≥50 years and is exacerbated by immune system aging. The main purpose of this review is to provide an overview of the burden of influenza and its potential prevention within the 50-64 age-group. These subjects account for a large proportion of the workforce, and play a central economic and social role. Individuals aged 50-64 years had a 3-times higher rate of hospitalization and a 9-fold higher mortality rate attributable to influenza than those aged 18-49-years, generating higher influenza-related hospitalization costs. Available data suggest that including healthy subjects aged 50-64 years in influenza vaccination recommendations would allow a broader population to be reached, reducing the economic and social burden of influenza.

Cost-Effectiveness of Extending the National Influenza Vaccination Program in South Korea: Does Vaccination of Older Adults Provide Health Benefits to the Entire Population?

The South Korean government has successfully improved influenza vaccination coverage for individuals aged 65 years or older as part of its National Immunization Program (NIP). Those aged 50–64 years without funded vaccination care have significantly lower vaccination rates and face a substantial risk of influenza-related complications. We use a dynamic epidemiological and economic model to investigate the cost-effectiveness of expanding the universal vaccine fund to include those aged 50–64. The epidemiological model is estimated using the susceptibility-infection-recovery model and influenza and influenza-like illness incidence rates, which were calculated by the National Health Insurance Service–National Sample Cohort from the 2008/09 to 2012/13 influenza seasons but excluding the 2009/10 season for pandemic influenza A (H1N1). The decision tree economic model is assessed from societal and healthcare sector perspectives. The proposed policy would eliminate 340,000 annual influenza cases and prevent 119 unnecessary deaths. From a societal perspective, the proposed policy would reduce costs by USD 68 million. From a healthcare perspective, the cost is USD 4318 per quality-adjusted life years. Within the study range, sensitivity analyses found consistent cost-effectiveness results. The influenza vaccine for adults aged 50–64 appears to be cost-saving or cost-effective and, thus, should be considered for the NIP.

Cost-Effectiveness of Influenza Vaccination Strategies in Adults: Older Adults Aged ≥65 Years, Adults Aged 50–64 Years, and At-Risk Adults Aged 19–64 Years

The high disease burden of influenza in elderly and chronically ill adults may be due to the suboptimal effectiveness and mismatch of the conventional trivalent influenza vaccine (TIV). This study evaluated the cost-effectiveness of quadrivalent (QIV), adjuvanted trivalent (ATIV), and high-dose quadrivalent (HD-QIV) vaccines versus TIV used under the current Korean National Immunization Program (NIP) in older adults aged ≥65 years. We also evaluated the cost-effectiveness of programs for at-risk adults aged 19–64 and adults aged 50–64. A one-year static population model was used to compare the costs and outcomes of alternative vaccination programs in each targeted group. Influenza-related parameters were derived from the National Health Insurance System claims database; other inputs were extracted from the published literature. Incremental cost-effectiveness ratios (ICERs) were assessed from a societal perspective. In the base case analysis (older adults aged ≥65 years), HD-QIV was superior, with the lowest cost and highest utility. Compared with TIV, ATIV was cost-effective (ICER $34,314/quality-adjusted life-year [QALY]), and QIV was not cost-effective (ICER $46,486/QALY). The cost-effectiveness of HD-QIV was robust for all parameters except for vaccine cost. The introduction of the influenza NIP was cost-effective or even cost-saving for the remaining targeted gr3oups, regardless of TIV or QIV.

Burden of severe illness associated with laboratory confirmed influenza in adults aged 50-64 years: A rapid review

BACKGROUND

While the high burden of illness caused by seasonal influenza in children and the elderly is well recognize, less is known about the burden in adults 50-64 years of age. The lack of data for this age group is a key challenge in evaluating the cost-effectiveness of immunization programs. We aimed to assess influenza-associated hospitalization and mortality rates and case fatality rates for hospitalized cases among adults aged 50-64 years.

METHODS

This rapid review was conducted according to the PRISMA; we searched MEDLINE, EMBASE, Cochrane, Web of Science, and grey literature for articles and reports published since 2010. Studies reporting rates of hospitalization and/or mortality associated with laboratory-confirmed influenza among adults 50-64 or 45-64 years of age for the 2010-11 through 2019-20 seasons were included.

RESULTS

Twenty studies from 13 countries were reviewed. Reported rates of hospitalization associated with laboratory-confirmed influenza were 5.7 to 112.8 per 100,000. Rates tended to be higher in the 2015-2019 compared with the 2010-2014 seasons and were higher in studies reporting data from high-income versus low and middle-income countries. Mortality rates were reported in only one study, with rates ranging from 0.8 to 3.5 per 100,000 in four different seasons. The case fatality rate among those hospitalized with influenza, as reported by population-based studies, ranged from 1.3% to 5.6%.

CONCLUSIONS

Seasonal influenza imposes a significant burden of morbidity on adults 50-64 years of age but with high heterogeneity across seasons and geographic regions. Ongoing surveillance is required to improve estimates of burden to better inform influenza vaccination and other public health policies.

Influenza Vaccination for the Prevention of Cardiovascular Disease in the Americas: Consensus document of the Inter-American Society of Cardiology and the Word Heart Federation

Background

Cardiovascular mortality is decreasing but remains the leading cause of death world-wide. Respiratory infections such as influenza significantly contribute to morbidity and mortality in patients with cardiovascular disease. Despite of proven benefits, influenza vaccination is not fully implemented, especially in Latin America.

Objective

The aim was to develop a regional consensus with recommendations regarding influenza vaccination and cardiovascular disease.

Methods

A multidisciplinary team composed by experts in the management and prevention of cardiovascular disease from the Americas, convened by the Inter-American Society of Cardiology (IASC) and the World Heart Federation (WHF), participated in the process and the formulation of statements. The modified RAND/UCLA methodology was used. This document was supported by a grant from the WHF.

Results

An extensive literature search was divided into seven questions, and a total of 23 conclusions and 29 recommendations were achieved. There was no disagreement among experts in the conclusions or recommendations.

Conclusions

There is a strong correlation between influenza and cardiovascular events. Influenza vaccination is not only safe and a proven strategy to reduce cardiovascular events, but it is also cost saving. We found several barriers for its global implementation and potential strategies to overcome them.

The Cost-Effectiveness of Expanding Vaccination with a Cell-Based Influenza Vaccine to Low Risk Adults Aged 50 to 64 Years in the United Kingdom

Background: In response to COVID-19, the UK National Health Service (NHS) extended influenza vaccination in 50- to 64-year-olds from at-risk only to all in this age group for the 2020/21 season. The objective of this research is to determine the cost-effectiveness of continuing to vaccinate all with a quadrivalent cell-based vaccine (QIVc) compared to returning to an at-risk only policy after the pandemic resolves. Methods: A dynamic transmission model, calibrated to match infection data from the UK, was used to estimate the clinical and economic impact of vaccination across 10 influenza seasons. The base case effectiveness of QIVc was 63.9% and the list price was GBP 9.94. Results: Vaccinating 50% of all 50- to 64-year-olds with QIVc reduced the average annual number of clinical infections (−682,000), hospitalizations (−5800) and deaths (−740) in the UK. The base case incremental cost per quality-adjusted life-year gained (ICER) of all compared to at-risk only was GBP6000 (NHS perspective). When the cost of lost productivity was considered, vaccinating all 50- to 64-year-olds with QIVc became cost-saving. Conclusion: Vaccinating all 50- to 64-year-olds with QIVc is likely to be cost-effective. The NHS should consider continuing this policy in future seasons.

Lowering the recommended age for the free and active offer of influenza vaccination in Italy: clinical and economic impact analysis in the Liguria region

Objective

we estimated the epidemiological and budget impact of lowering the recommended age for influenza immunization with quadrivalent vaccine actively offered and administered free of charge to persons over 50 years old by public immunization services.

Methods

a multi-cohort, deterministic, static Markov model was populated by real-world data on the clinical and economic impact of Influenza-Like Illness and Lower Respiratory Tract Infection over 1 year. Four scenarios featuring different vaccine coverage rates were compared with the base case; coverage rates in subjects with and without risk factors were considered separately.

Results

compared with the base case, adopting scenarios 1–4 would reduce the annual number of influenza cases by 6.5%, 10.8%, 13.8% and 3.4%, Emergency Department accesses by 10.7%, 9.1%, 15.4% and 4.6%, complications by 8.9%, 9.9%, 14.7% and 4.1%, and the hospitalization of complicated cases by 11%, 9.1%, 15.4% and 4.5%, respectively. The four scenarios would require an additional investment (vaccine purchase and administration) of €316,996, €529,174, €677,539, and €168,633, respectively, in comparison with the base case. Scenario 1 proved to be cost-saving in the 60–64-year age-group. The incremental costs of implementing the other hypothetical scenarios ranged from 2.7% (scenario 4) to 13.2% (scenario 3).

Conclusions

lowering the recommended age for influenza vaccination to 60 years would allow a high proportion of subjects at risk for severe influenza to be reached and would save money.

Inclusion of Safety-Related Issues in Economic Evaluations for Seasonal Influenza Vaccines: A Systematic Review

(1) Background: Vaccines for seasonal influenza are a good preventive and cost-effective strategy. However, it is unknown if and how these economic evaluations include the adverse events following immunization (AEFI), and what the impact of such inclusion is on the health economic outcomes. (2) Methods: We searched the literature, up to January 2020, to identify economic evaluations of seasonal influenza vaccines that considered AEFIs. The review protocol was published in PROSPERO (CDR42017058523). (3) Results: A total of 52 economic evaluations considered AEFI-related parameters in their analyses, reflecting 16% of the economic evaluations on seasonal influenza vaccines in the initial study selection. Most studies used the societal perspective (64%) and evaluated vaccination of children (37%). Where considered, studies included direct medical costs of AEFIs (90%), indirect costs (27%), and disutilities/quality-adjusted life years loss due to AEFIs (37%). The majority of these studies accounted for the effects of the costs of AEFI on cost-effectiveness for Guillain–Barré syndrome. In those papers allowing cost share estimation, direct medical cost of AFEIs was less than 2% of total direct costs. (4) Conclusions: Although the overall impact of AEFIs on the cost-effectiveness outcomes was found to be low, we urge their inclusion in economic evaluations of seasonal influenza vaccines to reflect comprehensive reports for the decision makers and end-users of the vaccination strategies.

Resource use and direct medical costs of acute respiratory illness in the UK based on linked primary and secondary care records from 2001 to 2009

Background

Previous studies have shown that influenza is associated with a substantial healthcare burden in the United Kingdom (UK), but more studies are needed to evaluate the resource use and direct medical costs of influenza in primary care and secondary care.

Methods

A retrospective observational database study in the UK to describe the primary care and directly-associated secondary care resource use, and direct medical costs of acute respiratory illness (ARI), according to age, and risk status (NCT Number: 01521416). Patients with influenza, ARI or influenza-related respiratory infections during 9 consecutive pre-pandemic influenza peak seasons were identified by READ codes in the linked Clinical Practice Research Datalink (CPRD) and Hospital Episodes Statistics (HES) dataset. The study period was from 21st January 2001 to 31st March 2009.

Results

A total of 156,193 patients had ≥1 general practitioner (GP) episode of ARI, and a total of 82,204 patients received ≥1 GP prescription, at a mean of 2.5 (standard deviation [SD]: 3.0) prescriptions per patient. The total cost of GP consultations and prescriptions equated to £462,827 per year per 100,000 patients. The yearly cost of prescribed medication for ARI was £319,732, at an estimated cost of £11,596,350 per year extrapolated to the UK, with 40% attributable to antibiotics. The mean cost of hospital admissions equated to a yearly cost of £981,808 per 100,000 patients. The total mean direct medical cost of ARI over 9 influenza seasons was £21,343,445 (SD: £10,441,364), at £136.65 (SD: £66.85) per case.

Conclusions

Extrapolating to the UK population, for pre-pandemic influenza seasons from 2001 to 2009, the direct medical cost of ARI equated to £86 million each year. More studies are needed to assess the costs of influenza disease to help guide public health decision-making for seasonal influenza in the UK.

Cost effectiveness of trivalent and quadrivalent influenza vaccines in 50- to 64-year-old adults in Korea

BACKGROUND

Influenza causes severe complications in at-risk populations, resulting in significant morbidity and mortality. Vaccination is the most effective measure to prevent infection and complications caused by seasonal influenza. However, no study has analyzed the cost-effectiveness of influenza vaccines in 50- to 64-year-olds in South Korea.

OBJECTIVE

We examined the application of the National Immunization Program (NIP) in 50- to 64-year-olds and compared the cost-effectiveness of quadrivalent influenza vaccine (QIV) with that of trivalent influenza vaccine (TIV) in South Korea.

METHODS

One-year static model was assumed by constructing separate decision trees for age subgroups: 50-54, 55-59, and 60-64. Each subgroup was divided into at-risk and not-at-risk groups. Using circulation data from previous studies and Korea Centers for Disease Control and Prevention, we estimated the probabilities of influenza infection, outpatient treatment, hospitalization, and deaths. Medical cost was estimated from 2015 to 2017 National Health Insurance Sharing Service claim data, while productivity losses from work absenteeism or death were estimated from labor and economic surveys of Korean government. Disutility was estimated based on previous studies.

RESULTS

Compared with non-vaccination, incremental cost-effectiveness ratios (ICERs) for the 50-54, 55-59, and 60-64 age groups for TIV were US$2010.90, US$2004.58, and US$1865.55, respectively, while for QIV were US$2187.17, US$2190.89, and US$2074.52, respectively. Compared with TIV, ICERs for QIV were US$4445.66, US$4578.06, and US$4751.93, respectively. All the aforementioned ICER values were lower than the 2017 Korean GDP per capita of US$29,742.839.

CONCLUSION

Implementing the NIP in the 50- to 64-year-old age group was found to be cost effective. Since both TIV and QIV were cost effective, we recommend QIV as the preferred option, based on its greater protection against Influenza B.

Cost-benefit analysis of a national influenza vaccination program in preventing hospitalisation costs in Australian adults aged 50-64 years old

INTRODUCTION

Influenza causes a significant burden among Australian adults aged 50-64, however, vaccine coverage rates remain suboptimal. The National Immunisation Program (NIP) currently funds influenza vaccinations in this age group only for those at high risk of influenza complications.

AIMS

The main aim of this study was to determine whether a strategy of expanding the government-funded vaccination program to all adults 50-64 in preventing influenza-related hospitalisations will be cost beneficial to the government.

METHODS

A cost-benefit analysis from a governmental perspective was performed using parameters informed by publicly available databases and published literature. Costs included cost of vaccinations and general practitioner consultation while benefits included the savings from averted respiratory and acute myocardial infarction (AMI) hospitalisations.

RESULTS

In the base-case scenario, the proposed policy would prevent 314 influenza/pneumonia, 388 other respiratory and 1482 AMI hospitalisations in a year. The government would save $8.03 million with an incremental benefit-cost ratio of 1.40. Most savings were due to averted AMI hospitalisations. In alternative scenarios cost savings ranged from saving of $31.4 million to additional cost to the government of $15.4 million, with sensitive variation in vaccine administration practices (through general practitioner or pharmacists) and vaccine effectiveness estimates.

DISCUSSION

Extension of the NIP to include adults 50-64 years of age is likely to be cost beneficial to the government, although this finding is sensitive to vaccine administration cost, which varies if provided through general practitioners or pharmacists; and to variation in vaccine effectiveness. An increased role of pharmacists in immunisation programs would likely result in cost savings in an expanded adult immunisation program.

Optimizing influenza vaccine policies for controlling 2009-like pandemics and regular outbreaks

Background

This study examined the effectiveness of various vaccine policies against influenza. The transmission rate was calculated by use of the time-series influenza-like illness case during the year of 2009 and recent epidemics in Taiwan.

Methods

We developed a stochastic compartmental model to analyze the transmission of influenza, where the population was stratified by location and age group, and the vaccine distribution was considered using the current policy. The simulation study compared the previous vaccine policy and a new policy with expanded coverage and various lengths of the vaccination campaign. The sensitivity analysis investigated different levels of vaccine efficacy to confirm the robustness of the recommended policies.

Results

Doubling vaccine coverage can decrease the number of infections effectively in the regular epidemic scenario. However, a peak of infections occurs if the duration of implementing vaccination is too long. In the 2009-like pandemic scenario, both increasing vaccine doses and reducing the program’s duration can mitigate infections, although the early outbreak restricts the effectiveness of vaccination programs.

Conclusions

The finding indicates that only increasing vaccine coverage can reduce influenza infections. To avoid the peak of infections, it is also necessary to execute the vaccination activity immediately. Vaccine efficacy significantly impacts the vaccination policy’s performance. When vaccine efficacy is low, neither increasing vaccination doses nor reducing vaccination timeframe prevents infections. Therefore, the variation in vaccine efficacy should be taken into account when making immunization policies against influenza.

Influenza vaccination in the elderly: Is a trial on mortality ethically acceptable?

The effectiveness of influenza vaccination in the elderly has long been a topic of debate, fueled by the absence of direct evidence from randomized trials on its effect on mortality and the methodological limitations of observational studies pointing this direction. It is argued that new placebo-controlled trials should be undertaken to resolve this uncertainty. However, such trials may be ethically questionable. To bring this discussion forward, we provide a comprehensive overview of the ethical challenges of an influenza vaccine efficacy trial designed to evaluate mortality in the elderly. An important condition in the justification of a trial is the existence of genuine uncertainty in regard to the answer to a research question. Therefore an extensive analysis of the existing levels of knowledge is needed to support the conclusion that an effect of vaccination on mortality is uncertain. Even if a so called "clinical equipoise" status applies, denying a control group vaccination would be problematic because vaccination is considered "competent care" and withholding vaccination could substantially increase patients' risk for influenza and its complications. Given the high burden of disease and already proven benefits of vaccination, such a trial is unlikely to meet the Declaration of Helsinki stating that the importance of a trial must outweigh the risk patients are exposed to. While a placebo-controlled trial in vaccine refusers may be considered, such a trial is unlikely to meet substantial methodological barriers regarding trial size and generalizability. We conclude that a new trial is unlikely to provide for a direct answer, let alone change current policy. At the same time, given the lack of consensus on the ethical acceptability of a placebo-controlled trial on the effect of influenza vaccination on mortality in the elderly, we invite researchers considering such trials to address the ethical challenges discussed in this manuscript.

Cost-utility analysis of antiviral use under pandemic influenza using a novel approach - linking pharmacology, epidemiology and heath economics

Simulation models are used widely in pharmacology, epidemiology and health economics (HEs). However, there have been no attempts to incorporate models from these disciplines into a single integrated model. Accordingly, we explored this linkage to evaluate the epidemiological and economic impact of oseltamivir dose optimisation in supporting pandemic influenza planning in the USA. An HE decision analytic model was linked to a pharmacokinetic/pharmacodynamics (PK/PD) - dynamic transmission model simulating the impact of pandemic influenza with low virulence and low transmissibility and, high virulence and high transmissibility. The cost-utility analysis was from the payer and societal perspectives, comparing oseltamivir 75 and 150 mg twice daily (BID) to no treatment over a 1-year time horizon. Model parameters were derived from published studies. Outcomes were measured as cost per quality-adjusted life year (QALY) gained. Sensitivity analyses were performed to examine the integrated model's robustness. Under both pandemic scenarios, compared to no treatment, the use of oseltamivir 75 or 150 mg BID led to a significant reduction of influenza episodes and influenza-related deaths, translating to substantial savings of QALYs. Overall drug costs were offset by the reduction of both direct and indirect costs, making these two interventions cost-saving from both perspectives. The results were sensitive to the proportion of inpatient presentation at the emergency visit and patients' quality of life. Integrating PK/PD-EPI/HE models is achievable. Whilst further refinement of this novel linkage model to more closely mimic the reality is needed, the current study has generated useful insights to support influenza pandemic planning.

Economic benefits of sharing and redistributing influenza vaccines when shortages occurred

Background

Recurrent influenza outbreak has been a concern for government health institutions in Taiwan. Over 10% of the population is infected by influenza viruses every year, and the infection has caused losses to both health and the economy. Approximately three million free vaccine doses are ordered and administered to high-risk populations at the beginning of flu season to control the disease. The government recommends sharing and redistributing vaccine inventories when shortages occur. While this policy intends to increase inventory flexibility, and has been proven as widely valuable, its impact on vaccine availability has not been previously reported.

Material and methods

This study developed an inventory model adapted to vaccination protocols to evaluate government recommended polices under different levels of vaccine production. Demands were uncertain and stratified by ages and locations according to the demographic data in Taiwan.

Results

When vaccine supply is sufficient, sharing pediatric vaccine reduced vaccine unavailability by 43% and overstock by 54%, and sharing adult vaccine reduced vaccine unavailability by 9% and overstock by 15%. Redistributing vaccines obtained greater gains for both pediatrics and adults (by 75%). When the vaccine supply is in short, only sharing pediatric vaccine yielded a 48% reduction of unused inventory, while other polices do not improve performances.

Conclusions

When implementing vaccination activities for seasonal influenza intervention, it is important to consider mismatches of demand and vaccine inventory. Our model confirmed that sharing and redistributing vaccines can substantially increase availability and reduce unused vaccines.

Systematic review of the cost-effectiveness of influenza immunization programs

BACKGROUND

Seasonal influenza immunization programs vary widely across jurisdictions. In Canada, some provinces offer universal programs while others target specific population groups. However, whether targeted or universal programs provide more benefit and value-for-money is unclear. The cost-effectiveness of influenza immunization programs was systematically reviewed to inform policy.

METHODS

Citation databases and the grey literature were searched for economic evaluations of influenza immunization programs. Eligible studies were appraised using the Scottish Intercollegiate Guidelines Network (SIGN) checklist with supplemental WHO vaccine-related questions. Data from high quality studies was extracted and the studies reviewed.

RESULTS

A total of 41influenza immunization studies were identified. Of these, 31 were high quality. For pregnant and postpartum women, vaccinating all versus only high risk women study results ranged from dominance (less costly and more effective) to $9773 per QALY gained (societal) and from dominance to $58,000 per QALY gained (healthcare system). Studies of vaccinating all versus only high risk children found vaccination to be dominant to $47,000 per QALY gained (societal), and dominant to $18,000 per QALY gained (healthcare system). Vaccinating high risk adults was highly cost-effective and vaccinating health care workers resulted in $35,000 per QALY gained. Results for healthy working adults were mixed and sensitive to vaccine uptake, efficacy, and productivity loss.

CONCLUSIONS

From the societal perspective, vaccination was cost-effective for children, pregnant and postpartum women, high risk groups, and in some cases, healthy working age adults. Immunization programs using group administration are more cost-effective than programs using individual administration. The perspective, programmatic design, setting, and inclusion of herd immunity affects cost-effectiveness. In regions with targeted programs, re-evaluating "high risk" criteria and consideration of a universal program is warranted.

Interdisciplinary pharmacometrics linking oseltamivir pharmacology, influenza epidemiology and health economics to inform antiviral use in pandemics

AIMS

A modular interdisciplinary platform was developed to investigate the economic impact of oseltamivir treatment by dosage regimen under simulated influenza pandemic scenarios.

METHODS

The pharmacology module consisted of a pharmacokinetic distribution of oseltamivir carboxylate daily area under the concentration-time curve at steady state (simulated for 75 mg and 150 mg twice daily regimens for 5 days) and a pharmacodynamic distribution of viral shedding duration obtained from phase II influenza inoculation data. The epidemiological module comprised a susceptible, exposed, infected, recovered (SEIR) model to which drug effect on the basic reproductive number (R₀ ), a measure of transmissibility, was linked by reduction of viral shedding duration. The number of infected patients per population of 100 000 susceptible individuals was simulated for a series of pandemic scenarios, varying oseltamivir dose, R₀ (1.9 vs. 2.7), and drug uptake (25%, 50%, and 80%). The number of infected patients for each scenario was entered into the health economics module, a decision analytic model populated with branch probabilities, disease utility, costs of hospitalized patients developing complications, and case-fatality rates. Change in quality-adjusted life years was determined relative to base case.

RESULTS

Oseltamivir 75 mg relative to no treatment reduced the median number of infected patients, increased change in quality-adjusted life years by deaths averted, and was cost-saving under all scenarios; 150 mg relative to 75 mg was not cost effective in low transmissibility scenarios but was cost saving in high transmissibility scenarios.

CONCLUSION

This methodological study demonstrates proof of concept that the disciplines of pharmacology, disease epidemiology and health economics can be linked in a single quantitative framework.

Cost-effectiveness analysis of quadrivalent versus trivalent influenza vaccine in Taiwan: A lifetime multi-cohort model

A government-funded trivalent influenza vaccine (TIV) program to prevent seasonal influenza was implemented in Taiwan since 1998. However, mismatch between the vaccine and circulating strains may occur. Alternatively, a quadrivalent influenza vaccine (QIV) includes all 4 influenza lineages could minimize the risk of mismatches. Therefore, QIV could be considered as an alternative strategy to enhance protection against seasonal influenza. The objective of the study was to analyze, from a governmental perspective, the cost-effectiveness of using QIV vs. TIV as a vaccination strategy in Taiwan. A lifetime multi-cohort, static Markov model was constructed with 9 age groups to assess the costs and effectiveness of QIV vs. TIV. Direct costs were obtained from a database released by the Ministry of Health and Welfare. Outcomes included life-years gained, quality-adjusted life years (QALYs) gained, influenza cases avoided and incremental cost-effectiveness ratios (ICERs). The discount rate of costs and effectiveness was set at 3.5% and the time horizon used in the model was 100 y. Results show that a vaccination strategy utilizing QIV instead of TIV would bring an additional 10,557 QALYs at an extra cost of US$39.4 million, yielding an ICER of US$3,015.07 per QALY gained. When setting the willingness-to-pay threshold at US$10,000, compared to TIV, the probability that QIV would be cost-effective was 98%. Sensitivity analyses show that ICER was sensitive to the changes of circulation of influenza virus subtypes and vaccine mismatch. From a governmental perspective, the QIV vaccination could be considered as a cost-effective strategy within the context of public health in Taiwan.

Estimated Human and Economic Burden of Four Major Adult Vaccine-Preventable Diseases in the United States, 2013

Low uptake of routinely recommended adult immunizations is a public health concern. Using data from the peer-reviewed literature, government disease-surveillance programs, and the US Census, we developed a customizable model to estimate human and economic burden caused by four major adult vaccine-preventable diseases (VPD) in 2013 in the United States, and for each US state individually. To estimate the number of cases for each adult VPD for a given population, we multiplied age-specific incidence rates obtained from the literature by age-specific 2013 Census population data. We then multiplied the estimated number of cases for a given population by age-specific, estimated medical and indirect (non-medical) costs per case. Adult VPDs examined were: (1) influenza, (2) pneumococcal disease (both invasive disease and pneumonia), (3) herpes zoster (shingles), and (4) pertussis (whooping cough). Sensitivity analyses simulated the impact of various epidemiological scenarios on the total estimated economic burden. Estimated US annual cost for the four adult VPDs was $26.5 billion (B) among adults aged 50 years and older, $15.3B (58 %) of which was attributable to those 65 and older. Among adults 50 and older, influenza, pneumococcal disease, herpes zoster, and pertussis made up $16.0B (60 %), $5.1B (19 %), $5.0B (19 %), and $0.4B (2 %) of the cost, respectively. Among those 65 and older, they made up $8.3B (54 %), $3.8B (25 %), $3.0B (20 %), and 0.2B (1 %) of the cost, respectively. Most (80-85 %) pneumococcal costs stemmed from nonbacteremic pneumococcal pneumonia (NPP). Cost attributable to adult VPD in the United States is substantial. Broadening adult immunization efforts beyond influenza only may help reduce the economic burden of adult VPD, and a pneumococcal vaccination effort, primarily focused on reducing NPP, may constitute a logical starting place. Sensitivity analyses revealed that a pandemic influenza season or change in size of the US elderly population could increase these costs dramatically.

Health and economic benefits of early vaccination and nonpharmaceutical interventions for a human influenza A (H7N9) pandemic: a modeling study

BACKGROUND

Vaccination for the 2009 pandemic did not occur until late in the outbreak, which limited its benefits. Influenza A (H7N9) is causing increasing morbidity and mortality in China, and researchers have modified the A (H5N1) virus to transmit via aerosol, which again heightens concerns about pandemic influenza preparedness.

OBJECTIVE

To determine how quickly vaccination should be completed to reduce infections, deaths, and health care costs in a pandemic with characteristics similar to influenza A (H7N9) and A (H5N1).

DESIGN

Dynamic transmission model to estimate health and economic consequences of a severe influenza pandemic in a large metropolitan city.

DATA SOURCES

Literature and expert opinion.

TARGET POPULATION

Residents of a U.S. metropolitan city with characteristics similar to New York City.

TIME HORIZON

Lifetime.

PERSPECTIVE

Societal.

INTERVENTION

Vaccination of 30% of the population at 4 or 6 months.

OUTCOME MEASURES

Infections and deaths averted and cost-effectiveness.

RESULTS OF BASE-CASE ANALYSIS

In 12 months, 48 254 persons would die. Vaccinating at 9 months would avert 2365 of these deaths. Vaccinating at 6 months would save 5775 additional lives and $51 million at a city level. Accelerating delivery to 4 months would save an additional 5633 lives and $50 million.

RESULTS OF SENSITIVITY ANALYSIS

If vaccination were delayed for 9 months, reducing contacts by 8% through nonpharmaceutical interventions would yield a similar reduction in infections and deaths as vaccination at 4 months.

LIMITATION

The model is not designed to evaluate programs targeting specific populations, such as children or persons with comorbid conditions.

CONCLUSION

Vaccination in an influenza A (H7N9) pandemic would need to be completed much faster than in 2009 to substantially reduce morbidity, mortality, and health care costs. Maximizing non-pharmaceutical interventions can substantially mitigate the pandemic until a matched vaccine becomes available.

PRIMARY FUNDING SOURCE

Agency for Healthcare Research and Quality, National Institutes of Health, and Department of Veterans Affairs.

Policy resistance undermines superspreader vaccination strategies for influenza

Theoretical models of infection spread on networks predict that targeting vaccination at individuals with a very large number of contacts (superspreaders) can reduce infection incidence by a significant margin. These models generally assume that superspreaders will always agree to be vaccinated. Hence, they cannot capture unintended consequences such as policy resistance, where the behavioral response induced by a new vaccine policy tends to reduce the expected benefits of the policy. Here, we couple a model of influenza transmission on an empirically-based contact network with a psychologically structured model of influenza vaccinating behavior, where individual vaccinating decisions depend on social learning and past experiences of perceived infections, vaccine complications and vaccine failures. We find that policy resistance almost completely undermines the effectiveness of superspreader strategies: the most commonly explored approaches that target a randomly chosen neighbor of an individual, or that preferentially choose neighbors with many contacts, provide at best a 2% relative improvement over their non-targeted counterpart as compared to 12% when behavioral feedbacks are ignored. Increased vaccine coverage in super spreaders is offset by decreased coverage in non-superspreaders, and superspreaders also have a higher rate of perceived vaccine failures on account of being infected more often. Including incentives for vaccination provides modest improvements in outcomes. We conclude that the design of influenza vaccine strategies involving widespread incentive use and/or targeting of superspreaders should account for policy resistance, and mitigate it whenever possible.

The cost-effectiveness of preexposure prophylaxis for HIV prevention in the United States in men who have sex with men

BACKGROUND

A recent randomized, controlled trial showed that daily oral preexposure chemoprophylaxis (PrEP) was effective for HIV prevention in men who have sex with men (MSM). The Centers for Disease Control and Prevention recently provided interim guidance for PrEP in MSM at high risk for HIV. Previous studies did not reach a consistent estimate of its cost-effectiveness.

OBJECTIVE

To estimate the effectiveness and cost-effectiveness of PrEP in MSM in the United States.

DESIGN

Dynamic model of HIV transmission and progression combined with a detailed economic analysis.

DATA SOURCES

Published literature.

TARGET POPULATION

MSM aged 13 to 64 years in the United States.

TIME HORIZON

Lifetime.

PERSPECTIVE

Societal.

INTERVENTION

PrEP was evaluated in both the general MSM population and in high-risk MSM and was assumed to reduce infection risk by 44% on the basis of clinical trial results.

OUTCOME MEASURES

New HIV infections, discounted quality-adjusted life-years (QALYs) and costs, and incremental cost-effectiveness ratios.

RESULTS OF BASE-CASE ANALYSIS

Initiating PrEP in 20% of MSM in the United States would reduce new HIV infections by an estimated 13% and result in a gain of 550,166 QALYs over 20 years at a cost of $172,091 per QALY gained. Initiating PrEP in a larger proportion of MSM would prevent more infections but at an increasing cost per QALY gained (up to $216,480 if all MSM receive PrEP). Preexposure chemoprophylaxis in only high-risk MSM can improve cost-effectiveness. For MSM with an average of 5 partners per year, PrEP costs approximately $50,000 per QALY gained. Providing PrEP to all high-risk MSM for 20 years would cost $75 billion more in health care-related costs than the status quo and $600,000 per HIV infection prevented, compared with incremental costs of $95 billion and $2 million per infection prevented for 20% coverage of all MSM.

RESULTS OF SENSITIVITY ANALYSIS

PrEP in the general MSM population would cost less than $100,000 per QALY gained if the daily cost of antiretroviral drugs for PrEP was less than $15 or if PrEP efficacy was greater than 75%.

LIMITATION

When examining PrEP in high-risk MSM, the investigators did not model a mix of low- and high-risk MSM because of lack of data on mixing patterns.

CONCLUSION

PrEP in the general MSM population could prevent a substantial number of HIV infections, but it is expensive. Use in high-risk MSM compares favorably with other interventions that are considered cost-effective but could result in annual PrEP expenditures of more than $4 billion.

PRIMARY FUNDING SOURCE

National Institute on Drug Abuse, Department of Veterans Affairs, and National Institute of Allergy and Infectious Diseases.

Health and economic impact of the seasonal influenza vaccination programme in England

BACKGROUND

The seasonal influenza vaccination programme in England targets individuals over 65 years old and in clinical risk groups.

METHODS

A model of influenza transmission and disease was fitted to weekly primary care consultations due to influenza in a typical pre-pandemic season (2006/2007). Different scenarios were constructed about influenza severity and how well vaccines match circulating strains to assess the impact and cost-effectiveness of the current vaccination programme.

RESULTS

A well-matched vaccine may reduce the incidence of laboratory-confirmed influenza illness from 8.2% (95% range 4.3-13%) to 5.9% (95% range 2.9-9.7%), with 56-73% of this due to indirect protection. The programme is likely to be cost-effective unless both low severity and poor matching is assumed.

CONCLUSION

The current seasonal influenza vaccination programme appears to substantially reduce disease burden and provides good value for money.

Probabilistic sensitivity analysis in health economics

Health economic evaluations have recently become an important part of the clinical and medical research process and have built upon more advanced statistical decision-theoretic foundations. In some contexts, it is officially required that uncertainty about both parameters and observable variables be properly taken into account, increasingly often by means of Bayesian methods. Among these, probabilistic sensitivity analysis has assumed a predominant role. The objective of this article is to review the problem of health economic assessment from the standpoint of Bayesian statistical decision theory with particular attention to the philosophy underlying the procedures for sensitivity analysis.

Cost-effectiveness of influenza vaccination of people aged 50-64 years in Australia: results are inconclusive

OBJECTIVE

Influenza cost-effectiveness studies use models for influenza clinical evolution based on a range of assumptions. We explore the importance of these assumptions and its implications in policy decisions.

METHODS

An influenza model was constructed to measure the cost-effectiveness of universal influenza vaccination of people over 50 years compared to current policy to vaccinate people over 65 years in Australia using available epidemiological data. We explored two scenarios, one with an Australian estimate of influenza like illness incidence, and one with a European estimate. Further, we estimated uncertainty of model structure and various parameter assumptions, and compared with a previous study.

RESULTS

The scenario and sensitivity analysis has shown the incremental cost-effectiveness ratio of the proposed compared to current policy varies from $112,000 to $6,000 per DALY. The model structure, parameter assumptions and limitations of existing epidemiological data lead to extensive unaccounted uncertainties in previous studies.

CONCLUSION

The lack of influenza epidemiological data makes the influenza cost-effectiveness studies that compare the universal influenza vaccinations of people over 50 years to current policy unreliable.

IMPLICATIONS

It is imperative to appraise unreliability of influenza cost-effectiveness studies in policy decisions. Research to acquire more data on influenza uncertainties in Australia should be funded.

Influenza vaccine for healthy adult workers: an issue for health authorities or employers?

OBJECTIVE

To contribute to the debate whether extending public coverage of influenza vaccination to healthy workers is cost-effective, particularly in the perspective of EU countries.

METHODS

First, we reviewed the recent international literature on the extension of vaccination to subjects aged 50-64 years in highly developed countries. Second, we estimated the broad economic impact of influenza vaccination on the Italian healthy adult working population. Finally, we ran a pilot observational study to assess the healthcare and labour outcomes of influenza vaccination on the employees of our organization.

RESULTS

The methodological weaknesses of the studies reviewed, all built on models, undermine the credibility of their optimistic results. The more cautious the model design, the less favourable the final results, as our conservative analysis on the Italian setting confirmed. The only common result was a steady relationship between potential vaccination benefits and indirect costs of absenteeism from work. This "modelling-based evidence" was confirmed by our internal survey: vaccinated workers showed less tendency to stay at home during influenza-like illness episodes and their relapses.

CONCLUSIONS

The economic advantage of extending public influenza vaccination to healthy adult workers is still uncertain and mainly relates to the indirect costs of productivity losses, making the extension strategy more a labour than a health issue.

Effectiveness and cost-effectiveness of vaccination against pandemic influenza (H1N1) 2009

BACKGROUND

Decisions on the timing and extent of vaccination against pandemic (H1N1) 2009 virus are complex.

OBJECTIVE

To estimate the effectiveness and cost-effectiveness of pandemic influenza (H1N1) vaccination under different scenarios in October or November 2009.

DESIGN

Compartmental epidemic model in conjunction with a Markov model of disease progression.

DATA SOURCES

Literature and expert opinion.

TARGET POPULATION

Residents of a major U.S. metropolitan city with a population of 8.3 million.

TIME HORIZON

Lifetime.

PERSPECTIVE

Societal.

INTERVENTIONS

Vaccination in mid-October or mid-November 2009.

OUTCOME MEASURES

Infections and deaths averted, costs, quality-adjusted life-years (QALYs), and incremental cost-effectiveness.

RESULTS OF BASE-CASE ANALYSIS

Assuming each primary infection causes 1.5 secondary infections, vaccinating 40% of the population in October or November would be cost-saving. Vaccination in October would avert 2051 deaths, gain 69 679 QALYs, and save $469 million compared with no vaccination; vaccination in November would avert 1468 deaths, gain 49 422 QALYs, and save $302 million.

RESULTS OF SENSITIVITY ANALYSIS

Vaccination is even more cost-saving if longer incubation periods, lower rates of infectiousness, or increased implementation of nonpharmaceutical interventions delay time to the peak of the pandemic. Vaccination saves fewer lives and is less cost-effective if the epidemic peaks earlier than mid-October.

LIMITATIONS

The model assumed homogenous mixing of case-patients and contacts; heterogeneous mixing would result in faster initial spread, followed by slower spread. Additional costs and savings not included in the model would make vaccination more cost-saving.

CONCLUSION

Earlier vaccination against pandemic (H1N1) 2009 prevents more deaths and is more cost-saving. Complete population coverage is not necessary to reduce the viral reproductive rate sufficiently to help shorten the pandemic.

PRIMARY FUNDING SOURCE

Agency for Healthcare Research and Quality and National Institute on Drug Abuse.

The cost-effectiveness of vaccinating pregnant women against seasonal influenza in England and Wales

We assessed the cost-effectiveness of vaccinating pregnant women against seasonal influenza in England and Wales, taking into account the timing of vaccination relative to both the influenza season and trimester of pregnancy. Women were assumed to be vaccinated in their second or third trimester. Vaccination between September and December was found to have an incremental cost-effectiveness ratio of £23,000 per quality adjusted life year (QALY) (95% CI £10,000-£140,000) if it is assumed that infants are partially protected through their mothers, and of £28,000 per QALY gained (95% CI £13,000-£200,000) if infants are not protected. If some vaccine protection lasts for a second season, then the ratio is only £15,000 per QALY gained (95% CI £6,000-£93,000). Most of the benefit of vaccination is in preventing symptomatic episodes, regardless of health care resource use. Extending vaccination beyond December is unlikely to be cost-effective unless there is good protection into a second influenza season. Key sources of uncertainty are the cost of vaccine delivery and the quality of life detriment due to a clinically apparent episode of confirmed influenza. The cost of vaccine purchase itself is relatively low.

Does influenza vaccination of older adult Medicare beneficiaries lower treatment costs for acute and chronic respiratory disease?

BACKGROUND

Influenza accounts for a large proportion of hospitalizations and deaths among older adults, resulting in substantial health care expenses. Influenza vaccinations are effective in reducing respiratory infections in younger populations, but it is less certain whether they reduce costs associated with respiratory infections among older adults.

OBJECTIVE

The purpose of this study was to determine whether influenza vaccination of older adult Medicare beneficiaries reduced costs associated with acute and chronic respiratory conditions during 3 recent influenza seasons.

METHODS

This study analyzed the relationship between influenza vaccination and costs for respiratory conditions among Medicare beneficiaries >or=55 years of age in influenza seasons (October-May) between 2002 and 2005 using data from the Medicare Current Beneficiary Survey. Two-part multiple regressions of vaccination status were estimated on the probability and cost of treating respiratory conditions in each influenza season controlling for influenza risk factors and other covariates. Various sensitivity tests were conducted by type of service, subgroup analysis for specific population risk segments, propensity score-matched comparisons, and difference equations.

RESULTS

The study sample included 13,402 Medicare beneficiaries for the 3 influenza seasons examined. Vaccination rates varied between 67.3% and 74.9% over the 3 influenza seasons. In unadjusted comparisons, no significant difference in the cost of treating respiratory conditions was found between vaccinated and unvaccinated beneficiaries in 2002/2003 (-$104), but vaccinated beneficiaries had significantly higher mean cost differentials in the more recent influenza seasons ($258 in 2003/2004, P = 0.012; $254 in 2004/2005, P = 0.003). Based on 2-part multiple regressions of vaccine status over the 3 seasons combined, costs of respiratory conditions were $142 dollars higher on average for vaccinated beneficiaries (P = 0.014). The base regression models showed no significant cost savings from vaccination in any year. Results of 2 of the 54 sensitivity tests that were conducted indicated significant savings from vaccination (inpatient costs for 2002/2003 and difference in total costs for persons unvaccinated in 2002/2003 but vaccinated in 2003/2004).

CONCLUSION

In this study of older adults, no significant cost savings were found with influenza vaccines in the 3 influenza seasons examined (2002-2005) when the outcome was measured in terms of differential spending for acute and chronic respiratory conditions.

Economic appraisal of Ontario's Universal Influenza Immunization Program: a cost-utility analysis

BACKGROUND

In July 2000, the province of Ontario, Canada, initiated a universal influenza immunization program (UIIP) to provide free seasonal influenza vaccines for the entire population. This is the first large-scale program of its kind worldwide. The objective of this study was to conduct an economic appraisal of Ontario's UIIP compared to a targeted influenza immunization program (TIIP).

METHODS AND FINDINGS

A cost-utility analysis using Ontario health administrative data was performed. The study was informed by a companion ecological study comparing physician visits, emergency department visits, hospitalizations, and deaths between 1997 and 2004 in Ontario and nine other Canadian provinces offering targeted immunization programs. The relative change estimates from pre-2000 to post-2000 as observed in other provinces were applied to pre-UIIP Ontario event rates to calculate the expected number of events had Ontario continued to offer targeted immunization. Main outcome measures were quality-adjusted life years (QALYs), costs in 2006 Canadian dollars, and incremental cost-utility ratios (incremental cost per QALY gained). Program and other costs were drawn from Ontario sources. Utility weights were obtained from the literature. The incremental cost of the program per QALY gained was calculated from the health care payer perspective. Ontario's UIIP costs approximately twice as much as a targeted program but reduces influenza cases by 61% and mortality by 28%, saving an estimated 1,134 QALYs per season overall. Reducing influenza cases decreases health care services cost by 52%. Most cost savings can be attributed to hospitalizations avoided. The incremental cost-effectiveness ratio is Can$10,797/QALY gained. Results are most sensitive to immunization cost and number of deaths averted.

CONCLUSIONS

Universal immunization against seasonal influenza was estimated to be an economically attractive intervention.

Is a Mass Immunization Program for Pandemic (H1N1) 2009 Good Value for Money? Early Evidence from the Canadian Experience

This work contributes informed estimates to the current debate about the pandemic (H1N1) 2009 mass immunization program's economic merits. We performed a cost-utility analysis of the (H1N1) 2009 mass immunization program in Ontario, Canada's most populous province. The analysis is based on a simulation model of a pandemic (H1N1) 2009 outbreak, surveillance data, and administrative data. We consider no immunization versus mass immunization reaching 30% of the population. Immunization program costs are expected to be $118 million in Ontario. Our analysis indicates this program will reduce influenza cases by 50%, preventing 35 deaths, and cutting treatment costs in half. A pandemic (H1N1) 2009 immunization program is likely to be highly cost-effective.

Effectiveness and cost-effectiveness of expanded antiviral prophylaxis and adjuvanted vaccination strategies for an influenza A (H5N1) pandemic

BACKGROUND

The pandemic potential of influenza A (H5N1) virus is a prominent public health concern of the 21st century.

OBJECTIVE

To estimate the effectiveness and cost-effectiveness of alternative pandemic (H5N1) mitigation and response strategies.

DESIGN

Compartmental epidemic model in conjunction with a Markov model of disease progression.

DATA SOURCES

Literature and expert opinion.

TARGET POPULATION

Residents of a U.S. metropolitan city with a population of 8.3 million.

TIME HORIZON

Lifetime.

PERSPECTIVE

Societal.

INTERVENTIONS

3 scenarios: 1) vaccination and antiviral pharmacotherapy in quantities similar to those currently available in the U.S. stockpile (stockpiled strategy), 2) stockpiled strategy but with expanded distribution of antiviral agents (expanded prophylaxis strategy), and 3) stockpiled strategy but with adjuvanted vaccine (expanded vaccination strategy). All scenarios assumed standard nonpharmaceutical interventions.

OUTCOME MEASURES

Infections and deaths averted, costs, quality-adjusted life-years (QALYs), and incremental cost-effectiveness.

RESULTS OF BASE-CASE ANALYSIS

Expanded vaccination was the most effective and cost-effective of the 3 strategies, averting 68% of infections and deaths and gaining 404 030 QALYs at $10 844 per QALY gained relative to the stockpiled strategy.

RESULTS OF SENSITIVITY ANALYSIS

Expanded vaccination remained incrementally cost-effective over a wide range of assumptions.

LIMITATIONS

The model assumed homogenous mixing of cases and contacts; heterogeneous mixing would result in faster initial spread, followed by slower spread. We did not model interventions for children or older adults; the model is not designed to target interventions to specific groups.

CONCLUSION

Expanded adjuvanted vaccination is an effective and cost-effective mitigation strategy for an influenza A (H5N1) pandemic. Expanded antiviral prophylaxis can help delay the pandemic while additional strategies are implemented.

PRIMARY FUNDING SOURCE

National Institutes of Health and Agency for Healthcare Research and Quality.

Effectiveness and cost-effectiveness of vaccination against pandemic influenza (H1N1) 2009

BACKGROUND

Decisions on the timing and extent of vaccination against pandemic (H1N1) 2009 virus are complex.

OBJECTIVE

To estimate the effectiveness and cost-effectiveness of pandemic influenza (H1N1) vaccination under different scenarios in October or November 2009.

DESIGN

Compartmental epidemic model in conjunction with a Markov model of disease progression.

DATA SOURCES

Literature and expert opinion.

TARGET POPULATION

Residents of a major U.S. metropolitan city with a population of 8.3 million.

TIME HORIZON

Lifetime.

PERSPECTIVE

Societal.

INTERVENTIONS

Vaccination in mid-October or mid-November 2009.

OUTCOME MEASURES

Infections and deaths averted, costs, quality-adjusted life-years (QALYs), and incremental cost-effectiveness.

RESULTS OF BASE-CASE ANALYSIS

Assuming each primary infection causes 1.5 secondary infections, vaccinating 40% of the population in October or November would be cost-saving. Vaccination in October would avert 2051 deaths, gain 69 679 QALYs, and save $469 million compared with no vaccination; vaccination in November would avert 1468 deaths, gain 49 422 QALYs, and save $302 million.

RESULTS OF SENSITIVITY ANALYSIS

Vaccination is even more cost-saving if longer incubation periods, lower rates of infectiousness, or increased implementation of nonpharmaceutical interventions delay time to the peak of the pandemic. Vaccination saves fewer lives and is less cost-effective if the epidemic peaks earlier than mid-October.

LIMITATIONS

The model assumed homogenous mixing of case-patients and contacts; heterogeneous mixing would result in faster initial spread, followed by slower spread. Additional costs and savings not included in the model would make vaccination more cost-saving.

CONCLUSION

Earlier vaccination against pandemic (H1N1) 2009 prevents more deaths and is more cost-saving. Complete population coverage is not necessary to reduce the viral reproductive rate sufficiently to help shorten the pandemic.

PRIMARY FUNDING SOURCE

Agency for Healthcare Research and Quality and National Institute on Drug Abuse.

Prescription of anti-influenza drugs for healthy adults: a systematic review and meta-analysis

In publicly funded health systems with finite resources, management decisions are based on assessments of clinical effectiveness and cost-effectiveness. The UK National Institute for Health and Clinical Excellence commissioned a systematic review to inform their 2009 update to guidance on the use of antiviral drugs for the treatment of influenza. We searched databases for studies of the use of neuraminidase inhibitors for the treatment of seasonal influenza. We present the results for healthy adults (ie, adults without known comorbidities) and people at-risk of influenza-related complications. There was an overall reduction in the median time to symptom alleviation in healthy adults by 0.57 days (95% CI -1.07 to -0.08; p=0.02; 2701 individuals) with zanamivir, and 0.55 days (95% CI -0.96 to -0.14; p=0.008; 1410 individuals) with oseltamivir. In those at risk, the median time to symptom alleviation was reduced by 0.98 days (95% CI -1.84 to -0.11; p=0.03; 1252 individuals) with zanamivir, and 0.74 days (95% CI -1.51 to 0.02; p=0.06; 1472 individuals) with oseltamivir. Little information was available on the incidence of complications. In view of the advantages and disadvantages of different management strategies for controlling seasonal influenza in healthy adults recommending the use of antiviral drugs for the treatment of people presenting with symptoms is unlikely to be the most appropriate course of action.

Influenza control in the 21st century: Optimizing protection of older adults

Older adults (> or =65 years of age) are particularly vulnerable to influenza illness. This is due to a waning immune system that reduces their ability to respond to infection, which leads to more severe cases of disease. The majority ( approximately 90%) of influenza-related deaths occur in older adults and, in addition, catastrophic disability resulting from influenza-related hospitalization represents a significant burden in this vulnerable population. Current influenza vaccines provide benefits for older adults against influenza; however, vaccine effectiveness is lower than in younger adults. In addition, antigenic drift is also a concern, as it can impact on vaccine effectiveness due to a mismatch between the vaccine virus strain and the circulating virus strain. As such, vaccines that offer higher and broader protection against both homologous and heterologous virus strains are desirable. Approaches currently available in some countries to meet this medical need in older adults may include the use of adjuvanted vaccines. Future strategies under evaluation include the use of high-dose vaccines; novel or enhanced adjuvantation of current vaccines; use of live attenuated vaccines in combination with current vaccines; DNA vaccines; recombinant vaccines; as well as the use of different modes of delivery and alternative antigens. However, to truly evaluate the benefits that these solutions offer, further efficacy and effectiveness studies, and better correlates of protection, including a precise measurement of the T cell responses that are markers for protection, are needed. While it is clear that vaccines with greater immunogenicity are required for older adults, and that adjuvanted vaccines may offer a short-term solution, further research is required to exploit the many other new technologies.

Coalition of advocates to vaccinate of Western European citizens aged 60 years and older

The high burden of infectious diseases in adults aged 60 years and older is disproportionate, considering that many of these diseases are vaccine-preventable. Based on careful analysis of the reasons for vaccination barriers/failures in the European population, the two European geriatric and gerontological societies (the European Union Geriatric Medicine Society [EUGMS] and the International Association of Gerontology and Geriatrics - European Region [IAGG-ER]) propose careful adaptation of current vaccine guidelines to promote preventive aspects, concerning both life threatening-diseases (influenza, pneumococcal pneumonia and tetanus/diphtheria) and diseases which adversely impact patients' quality of life (pertussis and herpes zoster). This consensus statement is designed to support official recommendations and improve the willingness to vaccinate the most rapidly growing segment of the population. The following guidelines are based on the importance of the sustainability of vaccine programs from midlife till extreme old age: - Promote healthy aging by optimizing health determinants of daily functions, active participation in society and individual quality of life; - Provide useful information to contribute toward harmonizing vaccine strategies at European level; - Support the public health, social and economic values of vaccination. Both healthcare professionals and consumers associations have a critical role to play in the implementation of such consensus clinical guidelines.

Increasing influenza vaccination coverage in recommended population groups in Europe

The clinical and economic burden of seasonal influenza is frequently underestimated. The cornerstone of controlling and preventing influenza is vaccination. National and international guidelines aim to implement immunization programs and targeted vaccination-coverage rates, which should help to enhance the vaccine uptake, especially in the at-risk population. This review purposes to highlight the vaccination guidelines and the actual vaccination situation in four target groups (the elderly, people with underlying chronic conditions, healthcare workers and children) from a European point of view.

Burden of influenza-like illness and effectiveness of influenza vaccination among working adults aged 50-64 years

BACKGROUND

Uncertainties regarding influenza disease impact and benefits of vaccination may contribute to low vaccination rates among adults aged 50-64 years.

METHODS

This prospective cohort study assessed the burden of influenza-like illness (ILI) among working adults aged 50-64 years and the effectiveness of influenza vaccination in reducing the rate of ILI and productivity losses. Employees of the University of Minnesota (Minneapolis) were invited via e-mail to participate in the study during October 2006. The study data were collected using internet-based surveys at baseline (October 2006) and during the follow-up period (from November 2006 through April 2007). Months included in the 2006-2007 influenza season were identified retrospectively from Minnesota Department of Health surveillance data. Vaccine effectiveness for reducing the rate of ILI, ILI-associated health care use, the number of days of illness, work loss, and reduced on-the-job productivity during the influenza season were assessed using multivariable regression models after controlling for important confounders.

RESULTS

Four hundred ninety-seven persons were included in the study, 85 (17.1%) of whom experienced an ILI. Among unvaccinated participants, ILI was responsible for 45% of all days of illness during the influenza season, 39% of all illness-related work days lost, and 49% of all days with illness-related reduced on-the-job productivity. In the multivariable regression analyses, vaccination was associated with a significant reduction in the rate of ILI (adjusted odds ratio, 0.48; 95% confidence interval, 0.27-0.86) and fewer days of illness, absenteeism, and impaired on-the-job performance.

CONCLUSION

ILIs were common among our study participants, accounting for a large portion of illness, work loss, and impaired work performance during the influenza season. Vaccination was associated with substantial health and productivity benefits. Vaccine delivery should be improved for this high-priority group.

Cost effectiveness of influenza vaccination in older adults: a critical review of economic evaluations for the 50- to 64-year age group

Several recent studies have assessed the benefits of extending influenza vaccination programmes, which are currently targeted primarily at those aged over 65 years, to those aged 50-64 years. We identified and reviewed all cost-effectiveness studies of influenza vaccination in those aged 50-64 years published before July 2008. While the studies suggest that vaccination in this age-group is likely to be cost effective, these results were dependent on several key assumptions. The estimates of serious outcomes due to influenza and the estimates of vaccine effectiveness (VE) against these outcomes were found to have the most influence on cost effectiveness. However, due to factors including mismatches between the measure of VE and the outcome under consideration, as well as various other data limitations, there is significant uncertainty around these key assumptions that was not well explored. There was a failure in some studies to report fundamental inputs such as discount rates. Overall, there was a general lack of transparency in the studies and, consequently, the conclusions around the cost effectiveness of influenza vaccine in those aged 50-64 years must be interpreted with caution.

Specific immunization issues in the occupational health setting

This article looks at the components of an effective occupational health vaccination programme and also reviews the legal basis for them. It addresses the issue of vaccine licensing including pre-clinical, clinical and post-licensing studies. It explores screening for vaccine preventable diseases in the occupational health setting and then addresses particular issues around hepatitis B, chicken pox, tuberculosis, measles, rubella, diphtheria, polio, mumps and hepatitis A.

Influenza-related hospitalisation and death in Australians aged 50 years and older

Estimating the true burden of influenza is problematic because relatively few hospitalisations or deaths are specifically coded as influenza related. Statistical regression techniques using influenza and respiratory syncytial virus surveillance data were used to estimate the number of excess hospitalisations and deaths attributable to influenza. Several International Classification of Diseases 10th Revision (ICD-10) groupings were used for both hospitalisation and mortality estimates, including influenza and pneumonia, other respiratory disorders, and circulatory disorders. For Australians aged 50-64 years, the annual excess hospitalisations attributable to influenza were 33.3 (95%CI: 23.2-43.4) per 100,000 for influenza and pneumonia and 57.6 (95%CI: 32.5-82.8) per 100,000 for other respiratory disorders. For Australians aged > or =65 years, the annual excess hospitalisations attributable to influenza were 157.4 (95%CI: 108.4-206.5) per 100,000 for influenza and pneumonia and 282.0 (95%CI: 183.7-380.3) per 100,000 for other respiratory disorders. The annual excess all-cause mortality attributable to influenza was 6.4 (95%CI: 2.6-10.2) per 100,000 and 116.4 (95%CI: 71.3-161.5) per 100,000, for Australians aged 50-64 years and those aged > or =65 years, respectively. In the age-group > or =65 years, a significant association was found between influenza activity and circulatory mortality. We conclude that influenza is responsible for a substantial amount of mortality and morbidity, over and above that which is directly diagnosed as influenza in Australians aged > or =50 years.