Economic evidence of influenza vaccination in children

Influenza Vaccination in Children Younger than 5 Years in the Region of Murcia (Spain), a Comparative Analysis among Vaccinating and Non-Vaccinating Parents: Data from the FLUTETRA Study

The high burden of influenza in children has driven numerous countries towards universal vaccination of healthy children from 6 to 59 months of age. The Region of Murcia was one of the pioneer Spanish regions to conduct a universal vaccination campaign and to use live-attenuated intranasal vaccine (LAIV) if age appropriate. This study aims to evaluate the parents' likeliness to vaccinate their children and to compare the profile of vaccinating/non-vaccinating parents. This study was designed as a prospective, real-world, survey-based data collection in the 2022-2023 season campaign. This study's sample was selected from those children whose information was available in the local Public Health System databases PERSAN and VACUSAN. Children received LAIV or intramuscular vaccine (IIV) depending on their age as per standard practice. The parent self-vaccination/intention to vaccinate themselves in this campaign (OR = 4.75), the compliance with the official vaccination schedule (OR = 3.41), and the prescription of antibiotics more than twice in the previous year (OR = 2.24) were strongly associated with children's vaccination. Overall, vaccinating parents were very satisfied with the vaccine (IIV: 67.5% vs. LAIV: 68.8%, p = 0.320), and most parents would rather have their children vaccinated with LAIV for the next campaign (43.0%). The main reasons for vaccinating were to protect the child (LAIV: 85.9% vs. IIV: 89.4%), and the predominant reasons for not vaccinating were a lack of healthcare professional recommendation (30.9%), and lack of information about the vaccination campaign (21.5%) and the vaccine itself (21.0%). The clinical context of parents and children was determinant in decision making, which was also influenced by the presence or absence of recommendation by healthcare professionals. Parents were generally very satisfied with the vaccine and showed their preference towards LAIV for future campaigns.

A Virion-Based Combination Vaccine Protects against Influenza and SARS-CoV-2 Disease in Mice

Vaccines targeting SARS-CoV-2 have been shown to be highly effective; however, the breadth against emerging variants and the longevity of protection remains unclear. Postimmunization boosting has been shown to be beneficial for disease protection, and as new variants continue to emerge, periodic (and perhaps annual) vaccination will likely be recommended. New seasonal influenza virus vaccines currently need to be developed every year due to continual antigenic drift, an undertaking made possible by a robust global vaccine production and distribution infrastructure. To create a seasonal combination vaccine targeting both influenza viruses and SARS-CoV-2 that is also amenable to frequent reformulation, we have developed an influenza A virus (IAV) genetic platform that allows the incorporation of an immunogenic domain of the SARS-CoV-2 spike (S) protein onto IAV particles. Vaccination with this combination vaccine elicited neutralizing antibodies and provided protection from lethal challenge with both pathogens in mice. This approach may allow the leveraging of established influenza vaccine infrastructure to generate a cost-effective and scalable seasonal vaccine solution for both influenza and coronaviruses.

IMPORTANCE The rapid emergence of SARS-CoV-2 variants since the onset of the pandemic has highlighted the need for both periodic vaccination “boosts” and a platform that can be rapidly reformulated to manufacture new vaccines. In this work, we report an approach that can utilize current influenza vaccine manufacturing infrastructure to generate combination vaccines capable of protecting from both influenza virus- and SARS-CoV-2-induced disease. The production of a combined influenza/SARS-CoV-2 vaccine may represent a practical solution to boost immunity to these important respiratory viruses without the increased cost and administration burden of multiple independent vaccines.

Is annual vaccination best? A modelling study of influenza vaccination strategies in children

INTRODUCTION

Annual vaccination of children against influenza is a key component of vaccination programs in many countries. However, past infection and vaccination may affect an individual's susceptibility to infection. Little research has evaluated whether annual vaccination is the best strategy. Using the United Kingdom as our motivating example, we developed a framework to assess the impact of different childhood vaccination strategies, specifically annual and biennial (every other year), on attack rate and expected number of infections.

METHODS AND FINDINGS

We present a multi-annual, individual-based, stochastic, force of infection model that accounts for individual exposure histories and disease/vaccine dynamics influencing susceptibility. We simulate birth cohorts that experience yearly influenza epidemics and follow them until age 18 to determine attack rates and the number of infections during childhood. We perform simulations under baseline conditions, with an assumed vaccination coverage of 44%, to compare annual vaccination to no and biennial vaccination. We relax our baseline assumptions to explore how our model assumptions impact vaccination program performance. At baseline, we observed less than half the number of infections between the ages 2 and 10 under annual vaccination in children who had been vaccinated at least half the time compared to no vaccination. When averaged over all ages 0-18, the number of infections under annual vaccination was 2.07 (2.06, 2.08) compared to 2.63 (2.62, 2.64) under no vaccination, and 2.38 (2.37, 2.40) under biennial vaccination. When we introduced a penalty for repeated exposures, we observed a decrease in the difference in infections between the vaccination strategies. Specifically, the difference in childhood infections under biennial compared to annual vaccination decreased from 0.31 to 0.04 as exposure penalty increased.

CONCLUSION

Our results indicate that while annual vaccination averts more childhood infections than biennial vaccination, this difference is small. Our work confirms the value of annual vaccination in children, even with modest vaccination coverage, but also shows that similar benefits of vaccination may be obtained by implementing a biennial vaccination program.

AUTHOR SUMMARY

Many countries include annual vaccination of children against influenza in their vaccination programs. In the United Kingdom (UK), annual vaccination of children aged of 2 to 10 against influenza is recommended. However, little research has evaluated whether annual vaccination is the best strategy, while accounting for how past infection and vaccination may affect an individual's susceptibility to infection in the current influenza season. Prior work has suggested that there may be a negative effect of repeated vaccination. In this work we developed a stochastic, individual-based model to assess the impact of repeated vaccination strategies on childhood infections. Specifically, we first compare annual vaccination to no vaccination and then annual vaccination to biennial (every other year) vaccination. We use the UK as our motivating example. We found that an annual vaccination strategy resulted in the fewest childhood infections, followed by biennial vaccination. The difference in number of childhood infections between the different vaccination strategies decreased when we introduced a penalty for repeated exposures. Our work confirms the value of annual vaccination in children, but also shows that similar benefits of vaccination can be obtained by implementing a biennial vaccination program, particularly when there is a negative effect of repeated vaccinations.

Clinical characteristics and outcomes of mixed virus or bacterial infection in children with laboratory-confirmed influenza infection

BACKGROUND/PURPOSE

This study investigated the demographic characteristics and influenza complications of paediatric patients and explored the association of different influenza virus types and viral and bacterial coinfections with disease severity.

METHODS

This retrospective cohort study used data collected in 2010-2016 from the Chang Gung Research Database (CGRD), the largest collection of multi-institutional electronic medical records in Taiwan. Data were retrieved for children aged 0-18 years with laboratory-confirmed influenza. We extracted and analysed the demographic characteristics and the data on clinical features, complications, microbiological information, and advanced therapies of each case.

RESULTS

We identified 6193 children with laboratory-confirmed influenza, of whom 1964 (31.7%) were hospitalised. The age of patients with influenza A infection was lower than that of patients with influenza B (4.48 vs. 6.68, p < 0.001). Patients with influenza B infection had a higher incidence of myositis or rhabdomyolysis (4.4%, p < 0.001) and a higher need for advanced therapies (OR, 1.96; 95% CI, 1.32-2.9, p < 0.001). In addition to bacterial (OR, 9.07; 95% CI, 5.29-15.54, p < 0.001) and viral coinfection (OR, 7.73; 95% CI, 5.4-11.07, p < 0.001), dual influenza A and B infection was also a risk factor for influenza complications (OR, 2.13; 95% CI, 1.47-3.09, p < 0.001).

CONCLUSION

Dual influenza A and B infection and bacterial coinfection can contribute to influenza complications. Early recognition of any influenza complication is critical for the timely initiation of organ-specific advanced therapies to improve influenza-associated outcomes.

Burden, effectiveness and safety of influenza vaccines in elderly, paediatric and pregnant populations

Vaccination is the most practical means available for preventing influenza. Influenza vaccines require frequent updates to keep pace with antigenic drift of the virus, and the effectiveness, and sometimes the safety, of the vaccine can therefore vary from season to season. Three key populations that the World Health Organization recommends should be prioritized for influenza vaccination are pregnant women, children younger than 5 years of age and the elderly. This review discusses the burden of influenza and the safety and effectiveness profile of influenza vaccines recommended for these groups.

Model Comparisons of the Effectiveness and Cost-Effectiveness of Vaccination: A Systematic Review of the Literature

OBJECTIVES

To describe all published articles that have conducted comparisons of model-based effectiveness and cost-effectiveness results in the field of vaccination. Specific objectives were to 1) describe the methodologies used and 2) identify the strengths and limitations of the studies.

METHODS

We systematically searched MEDLINE and Embase databases for studies that compared predictions of effectiveness and cost-effectiveness of vaccination of two or more mathematical models. We categorized studies into two groups on the basis of their data source for comparison (previously published results or new simulation results) and performed a qualitative synthesis of study conclusions.

RESULTS

We identified 115 eligible articles (only 5% generated new simulations from the reviewed models) examining the effectiveness and cost-effectiveness of vaccination against 14 pathogens (69% of studies examined human papillomavirus, influenza, and/or pneumococcal vaccines). The goal of most of studies was to summarize evidence for vaccination policy decisions, and cost-effectiveness was the most frequent outcome examined. Only 33%, 25%, and 3% of studies followed a systematic approach to identify eligible studies, assessed the quality of studies, and performed a quantitative synthesis of results, respectively. A greater proportion of model comparisons using published studies followed a systematic approach to identify eligible studies and to assess their quality, whereas more studies using new simulations performed quantitative synthesis of results and identified drivers of model conclusions. Most comparative modeling studies concluded that vaccination was cost-effective.

CONCLUSIONS

Given the variability in methods used to conduct/report comparative modeling studies, guidelines are required to enhance their quality and transparency and to provide better tools for decision making.

A retrospective observational analysis of post-pandemic influenza-related outcomes in the United Kingdom, 2010-2014

This study set out to evaluate influenza- and respiratory-related illnesses recorded during primary care physician consultations in England following the H1N1 pandemic in 2009 and to enable the development of a dynamic disease model. Data were obtained from the Clinical Practice Research Datalink of primary care records over four influenza seasons (2010–2014). The primary outcome of the study was incidence of influenza- and respiratory-related diagnoses, calculated per practice and by season and age group. Upper respiratory tract infection diagnoses were most frequently recorded (mean seasonal practice level incidence; 3,762 consultations per 100,000 [SD = 1,989]), and influenza-related diagnoses were least frequently recorded across all seasons, except one. Incidence rates for the under 18 population were higher than those for the general population, in particular for upper respiratory tract infection (range of 8,024–9,950 versus 3,228–4,120, respectively) and otitis media diagnoses (2,668–3,652 versus 782–1,057, respectively). For influenza-related diagnoses, the 65+ age group, the 0 to <2 and 2 to <4 groups had a higher risk (risk ratio = 1.33, 1.12 and 1.16, respectively) than other age groups. This study provides valuable insight into the incidence of influenza- and respiratory-related diagnoses in the primary care setting in England, and suggests a higher burden of disease in young children and the elderly. The study also indicates that some influenza illness is likely to be reported under respiratory-related diagnoses, given the low incidence of influenza-related diagnoses in the study.

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.

Cost Effectiveness of Influenza Vaccine Choices in Children Aged 2-8 Years in the U.S

INTRODUCTION

Prior evidence found live attenuated influenza vaccine (LAIV) more effective than inactivated influenza vaccine (IIV) in children aged 2-8 years, leading CDC in 2014 to prefer LAIV use in this group. However, since 2013, LAIV has not proven superior, leading CDC in 2015 to rescind their LAIV preference statement. Here, the cost effectiveness of preferred LAIV use compared with IIV in children aged 2-8 years is estimated.

METHODS

A Markov model estimated vaccination strategy cost effectiveness in terms of cost per quality-adjusted life-year gained. Base case assumptions were equal vaccine uptake; IIV use when LAIV was not indicated (in 11.7% of the cohort); and no indirect vaccination effects. Sensitivity analyses included estimates of indirect effects from both equation- and agent-based models. Analyses were performed in 2014-2015.

RESULTS

Using prior effectiveness data in children aged 2-8 years (LAIV=83%, IIV=64%), preferred LAIV use was less costly and more effective than IIV (dominant), with results sensitive only to LAIV and IIV effectiveness variation. Using 2014-2015 U.S. effectiveness data (LAIV=0%, IIV=15%), IIV was dominant. In two-way sensitivity analyses, LAIV use was cost saving over the entire range of IIV effectiveness (0%-81%) when absolute LAIV effectiveness was >7.1% higher than IIV, but never cost saving when absolute LAIV effectiveness was <3.5% higher than IIV.

CONCLUSIONS

Results support CDC's decision to no longer prefer LAIV use and provide guidance on effectiveness differences between influenza vaccines that might lead to preferential LAIV recommendation for children aged 2-8 years.

Clinical features of children hospitalized with influenza A and B infections during the 2012-2013 influenza season in Italy

Background

Influenza is a major public health issue worldwide. It is characterized by episodes of infection that involve hundreds of millions of people each year. Since that in the seasons 2010–2011 and 2011–2012 the circulation of FLUB was decreasing we evaluated the clinical presentation, demographic characteristics, admitting department, and length of stay in children who contracted influenza admitted to Bambino Gesù Children’s Hospital, during the 2012–2013 influenza season, with the aim to establish if the recover of FLUB was associated to a clinical worsening, in comparison with those due to FLUA.

Methods

A total of 133 respiratory specimens, collected from patients with symptoms of respiratory tract infections, positive for the Influenza A and B viruses (FLUA and B) were subtyped. Comparisons between the FLUA and FLUB groups were performed with the one-way ANOVA for continuous parametric variables, the Mann-Whitney test for non-parametric variables, or the Chi-Square test or Fisher’s exact test (if cells <5) for categorical variables.

Results

87.09 % of the FLUA isolates were the H1N1 subtype and 12.90 % were H3N2. Among the FLUB isolates, 91.54 % were the B/Yamagata/16/88 lineage and 8.45 % were the B/Victoria/02/87 lineage. The largest number of FLUA/H1N1 cases was observed in children less than 1 years old, while the B/Yamagata/16/88 lineage was most prevalent in children 3–6 years old. Fever was a common symptom for both FLUA and B affected patients. However, respiratory symptoms were more prevalent in patients affected by FLUA. The median length of stay in the hospital was 5 days for FLUA and 3 days for FLUB.

Conclusions

The clinical features correlated to different Influenza viruses, and relevant subtypes, were evaluated concluding that the increasing of FLUB in the season 2012–2013 was without any dramatic change in clinical manifestation. Our findings suggest, finally, that a stronger commitment to managing patients affected by FLUA is required, as the disease is more severe than FLUB.

Targeted vaccination in healthy school children - Can primary school vaccination alone control influenza?

BACKGROUND

The UK commenced an extension to the seasonal influenza vaccination policy in autumn 2014 that will eventually see all healthy children between the ages of 2-16 years offered annual influenza vaccination. Models suggest that the new policy will be both highly effective at reducing the burden of influenza as well as cost-effective. We explore whether targeting vaccination at either primary or secondary schools would be more effective and/or cost-effective than the current strategy.

METHODS

An age-structured deterministic transmission dynamic SEIR-type mathematical model was used to simulate a national influenza outbreak in England. Costs including GP consultations, hospitalisations due to influenza and vaccinations were compared to potential gains in quality-adjusted life years achieved through vaccinating healthy children. Costs and benefits of the new JCVI vaccination policy were estimated over a single season, and compared to the hypothesised new policies of targeted and heterogeneous vaccination.

FINDINGS AND CONCLUSION

All potential vaccination policies were highly cost-effective. Influenza transmission can be eliminated for a particular season by vaccinating both primary and secondary school children, but not by vaccinating only one group. The most cost-effective policy overall is heterogeneous vaccination coverage with 48% uptake in primary schools and 34% in secondary schools. The Joint Committee on Vaccination and Immunisation can consider a modification to their policy of offering seasonal influenza vaccinations to all healthy children of ages 2-16 years.

Public health impact and cost-effectiveness of intranasal live attenuated influenza vaccination of children in Germany

In 2011, intranasally administered live attenuated influenza vaccine (LAIV) was approved in the EU for prophylaxis of seasonal influenza in 2-17-year-old children. Our objective was to estimate the potential epidemiological impact and cost-effectiveness of an LAIV-based extension of the influenza vaccination programme to healthy children in Germany. An age-structured dynamic model of influenza transmission was developed and combined with a decision-tree to evaluate different vaccination strategies in the German health care system. Model inputs were based on published literature or were derived by expert consulting using the Delphi technique. Unit costs were drawn from German sources. Under base-case assumptions, annual routine vaccination of children aged 2-17 years with LAIV assuming an uptake of 50% would prevent, across all ages, 16 million cases of symptomatic influenza, over 600,000 cases of acute otitis media, nearly 130,000 cases of community-acquired pneumonia, nearly 1.7 million prescriptions of antibiotics and over 165,000 hospitalisations over 10 years. The discounted incremental cost-effectiveness ratio was <euro> 1,228 per quality-adjusted life year gained from a broad third-party payer perspective (including reimbursed direct costs and specific transfer payments), when compared with the current strategy of vaccinating primarily risk groups with the conventional trivalent inactivated vaccine. Inclusion of patient co-payments and indirect costs in terms of productivity losses resulted in discounted 10-year cost savings of <euro> 3.4 billion. In conclusion, adopting universal influenza immunisation of healthy children and adolescents would lead to a substantial reduction in influenza-associated disease at a reasonable cost to the German statutory health insurance system. On the basis of the epidemiological and health economic simulation results, a recommendation of introducing annual routine influenza vaccination of children 2-17 years of age might be taken into consideration.

Seasonal influenza vaccination for children in Thailand: a cost-effectiveness analysis

BACKGROUND

Seasonal influenza is a major cause of mortality worldwide. Routine immunization of children has the potential to reduce this mortality through both direct and indirect protection, but has not been adopted by any low- or middle-income countries. We developed a framework to evaluate the cost-effectiveness of influenza vaccination policies in developing countries and used it to consider annual vaccination of school- and preschool-aged children with either trivalent inactivated influenza vaccine (TIV) or trivalent live-attenuated influenza vaccine (LAIV) in Thailand. We also compared these approaches with a policy of expanding TIV coverage in the elderly.

METHODS AND FINDINGS

We developed an age-structured model to evaluate the cost-effectiveness of eight vaccination policies parameterized using country-level data from Thailand. For policies using LAIV, we considered five different age groups of children to vaccinate. We adopted a Bayesian evidence-synthesis framework, expressing uncertainty in parameters through probability distributions derived by fitting the model to prospectively collected laboratory-confirmed influenza data from 2005-2009, by meta-analysis of clinical trial data, and by using prior probability distributions derived from literature review and elicitation of expert opinion. We performed sensitivity analyses using alternative assumptions about prior immunity, contact patterns between age groups, the proportion of infections that are symptomatic, cost per unit vaccine, and vaccine effectiveness. Vaccination of children with LAIV was found to be highly cost-effective, with incremental cost-effectiveness ratios between about 2,000 and 5,000 international dollars per disability-adjusted life year averted, and was consistently preferred to TIV-based policies. These findings were robust to extensive sensitivity analyses. The optimal age group to vaccinate with LAIV, however, was sensitive both to the willingness to pay for health benefits and to assumptions about contact patterns between age groups.

CONCLUSIONS

Vaccinating school-aged children with LAIV is likely to be cost-effective in Thailand in the short term, though the long-term consequences of such a policy cannot be reliably predicted given current knowledge of influenza epidemiology and immunology. Our work provides a coherent framework that can be used for similar analyses in other low- and middle-income countries.

The epidemiological impact of childhood influenza vaccination using live-attenuated influenza vaccine (LAIV) in Germany: predictions of a simulation study

Background

Routine annual influenza vaccination is primarily recommended for all persons aged 60 and above and for people with underlying chronic conditions in Germany. Other countries have already adopted additional childhood influenza immunisation programmes. The objective of this study is to determine the potential epidemiological impact of implementing paediatric influenza vaccination using intranasally administered live-attenuated influenza vaccine (LAIV) in Germany.

Methods

A deterministic age-structured model is used to simulate the population-level impact of different vaccination strategies on the transmission dynamics of seasonal influenza in Germany. In our base-case analysis, we estimate the effects of adding a LAIV-based immunisation programme targeting children 2 to 17 years of age to the existing influenza vaccination policy. The data used in the model is based on published evidence complemented by expert opinion.

Results

In our model, additional vaccination of children 2 to 17 years of age with LAIV leads to the prevention of 23.9 million influenza infections and nearly 16 million symptomatic influenza cases within 10 years. This reduction in burden of disease is not restricted to children. About one third of all adult cases can indirectly be prevented by LAIV immunisation of children.

Conclusions

Our results demonstrate that vaccinating children 2–17 years of age is likely associated with a significant reduction in the burden of paediatric influenza. Furthermore, annual routine childhood vaccination against seasonal influenza is expected to decrease the incidence of influenza among adults and older people due to indirect effects of herd protection. In summary, our model provides data supporting the introduction of a paediatric influenza immunisation programme in Germany.

Key issues for estimating the impact and cost-effectiveness of seasonal influenza vaccination strategies

Many countries have considered or are considering modifying their seasonal influenza immunization policies. Estimating the impact of such changes requires understanding the existing clinical and economic burden of influenza, as well as the potential impact of different vaccination options. Previous studies suggest that vaccinating clinical risk groups, health care workers, children and the elderly may be cost-effective. However, challenges in such estimation include: (1) potential cases are not usually virologically tested; (2) cases have non-specific symptoms and are rarely reported to surveillance systems; (3) endpoints for influenza proxies (such as influenza-like illness) need to be matched to case definitions for treatment costs, (4) disease burden estimates vary from year to year with strain transmissibility, virulence and prior immunity, (5) methods to estimate productivity losses due to influenza vary, (6) vaccine efficacy estimates from trials differ due to variation in subtype prevalence, vaccine match and case ascertainment, and (7) indirect (herd) protection from vaccination depends on setting-specific variables that are difficult to directly measure. Given the importance of knowing the impact of changes to influenza policy, such complexities need careful treatment using tools such as population-based trial designs, meta-analyses, time-series analyses and transmission dynamic models.

Economic benefits of inactivated influenza vaccines in the prevention of seasonal influenza in children

The aim of this study was to systematically review published studies that evaluated the efficiency of inactivated influenza vaccination in preventing seasonal influenza in children. The vaccine evaluated was the influenza-inactivated vaccine in 10 studies and the virosomal inactivated vaccine in 3 studies. The results show that yearly vaccination of children with the inactivated influenza vaccine saves money from the societal and family perspectives but not from the public or private provider perspective. When vaccination does not save money, the cost-effectiveness ratios were very acceptable. It can be concluded, that inactivated influenza vaccination of children is a very efficient intervention.

Cost-effectiveness of childhood influenza vaccination in England and Wales: Results from a dynamic transmission model

This study uses a dynamic influenza transmission model to directly compare the cost-effectiveness of various policies of annual paediatric influenza vaccination in England and Wales, varying the target age range and level of coverage. The model accounts for both the protection of those immunised and the indirect protection of the rest of the population via herd immunity. The impact of augmenting current practice with a policy to vaccinate pre-school age children, on their own or with school age children, was assessed in terms of quality adjusted life years and health service costs. Vaccinating 2-18 year olds was estimated to be the most cost-effective policy in an incremental cost-effectiveness analysis, at an assumed annual vaccine uptake rate of 50%. The mean incremental cost-effectiveness ratios for this policy was estimated at £251/QALY relative to current practice. Paediatric vaccination would appear to be a highly cost-effective intervention that directly protects those targeted for vaccination, with indirect protection extending to both the very young and the elderly.

Burden of paediatric influenza in Western Europe: a systematic review

Background

Influenza illness in children causes significant clinical and economic burden. Although some European countries have adopted influenza immunisation policies for healthy children, the debate about paediatric influenza vaccination in most countries of the European Union is ongoing. Our aim was to summarise influenza burden (in terms of health outcomes and economic burden) in children in Western Europe via a systematic literature review.

Methods

We conducted a systematic literature search of PubMed, EMBASE, and the Cochrane Library (1970-April 2011) and extracted data on influenza burden in children (defined as aged ≤ 18 years) from 50 publications (13 reporting laboratory-confirmed influenza; 37 reporting influenza-like illness).

Results

Children with laboratory-confirmed influenza experienced hospitalisations (0.3%-20%), medical visits (1.7-2.8 visits per case), antibiotic prescriptions (7%-55%), and antipyretic or other medications for symptomatic relief (76%-99%); young children and those with severe illness had the highest rates of health care use. Influenza in children also led to absenteeism from day care, school, or work for the children, their siblings, and their parents. Average (mean or median) length of absence from school or day care associated with confirmed influenza ranged from 2.8 to 12.0 days for the children, from 1.3 to 6.0 days for their siblings, and from 1.3 to 6.3 days for their parents. Influenza negatively affected health-related quality of life in children with asthma, including symptoms and activities; this negative effect was smaller in vaccinated children than in non-vaccinated children.

Conclusions

Influenza burden in children is substantial and has a significant direct impact on the ill children and an indirect impact on their siblings and parents. The identified evidence regarding the burden of influenza may help inform both influenza antiviral use in children and paediatric immunisation policies in European countries.

Economic evaluations of childhood influenza vaccination: a critical review

The potential benefits of influenza vaccination programmes targeted at children have gained increasing attention in recent years. We conducted a literature search of economic evaluations of influenza vaccination in those aged ≤18 years. The search revealed 20 relevant articles, which were reviewed. The studies differed widely in terms of the costs and benefits that were included. The conclusions were generally favourable for vaccination, but often applied a wider perspective (i.e. including productivity losses) than the reference case for economic evaluations used in many countries. Several evaluations estimated outcomes from a single-year epidemiological study, which may limit their validity given the year-to-year variation in influenza transmissibility, virulence, vaccine match and prior immunity. Only one study used a dynamic transmission model able to fully incorporate the indirect herd protection to the wider community. The use of dynamic models offers great scope to capture the population-wide implications of seasonal vaccination efforts, particularly those targeted at children.

Seasonal influenza vaccination of healthy working-age adults: a review of economic evaluations

The recent impact of influenza on the working-age population of the US has led to changes in the recommendations for vaccination against seasonal influenza; however, the implications of vaccinating such a population have been debated. A review of cost-effectiveness analyses of vaccinating the working-age population of the US against seasonal influenza was conducted using articles published between January 1990 and January 2010. Studies considered for inclusion were identified using MEDLINE, EMBASE and Econlit. Reviewers worked in pairs, and each team member independently extracted relevant data using a standard abstraction form. The source and appropriateness of parameters (epidemiological data, probabilities and costs), the designs employed and the sufficiency of sensitivity analysis were considered during review. Key inputs extracted from the selected studies included influenza or influenza-like illness attack rates, outpatient visits averted, total vaccination days and lost workdays. Seven studies were identified as appropriate for this review. All studies were conducted in the US and from the societal perspective; three were randomized controlled trials and the remaining four were economic simulation models comparing vaccination and influenza antiviral drugs or no intervention; analyses focused on healthy working-age adults aged 18-49 years. Results ranged from net savings of $US68.96 to net costs of $US85.92 per person vaccinated (four studies) and net costs of $US104-1005 per episode of influenza averted (one study). Only two studies reported cost-effectiveness ratios; these ranged from $US26,565 to $US50,512 per quality-adjusted life-year gained. Nearly all of the studies conducted sensitivity analysis; results were most sensitive to variation in wage rates, levels of worker productivity, the costs and effectiveness of vaccination, and the rate of influenza illness. Review of the included studies suggests that seasonal influenza vaccination of healthy, working-age adults is generally not cost saving, requiring an investment to generate health benefits. The decision to vaccinate such a group will depend upon the societal and payer valuation of those benefits.

Marketing paediatric influenza vaccination: results of a major metropolitan trial

Please cite this paper as: Van Buynder et al. (2010) Marketing paediatric influenza vaccination: results of a major metropolitan trial. Influenza and Other Respiratory Viruses 5(1), 33–38.

Objectives  After a cluster of rapidly fulminant influenza related toddler deaths in a Western Australian metropolis, children aged six to 59 months were offered influenza vaccination in subsequent winters. Some parental resistance was expected and previous poor uptake of paediatric influenza vaccination overseas was noted. A marketing campaign addressing barriers to immunization was developed to maximise uptake.

Design  Advertising occurred in major statewide newspapers, via public poster displays and static ‘eye‐lite’ displays, via press releases, via a series of rolling radio advertisements, via direct marketing to child care centres, and via a linked series of web‐sites. Parents were subsequently surveyed to assess reasons for vaccination.

Main Outcome Results  The campaign produced influenza vaccination coverage above that previously described elsewhere and led to a proportionate reduction in influenza notifications in this age group compared to previous seasons.

Conclusions  Influenza in children comes with significant morbidity and some mortality. Paediatric influenza vaccination is safe, well tolerated and effective if two doses are given. A targeted media campaign can increase vaccine uptake if it reinforces the seriousness of influenza and addresses community ‘myths’ about influenza and influenza vaccine. The lessons learned enabling enhancements of similar programs elsewhere.

2005 and 2006 seasonal influenza vaccination coverage rates in 10 countries in Africa, Asia Pacific, Europe, Latin America and the Middle East

Recommendations for seasonal influenza vaccination are standard in most developed countries. Many rapidly developing countries have recently begun to adopt recommendations for high-risk target groups, such as the elderly. Population-based surveys to determine use, rather than purchases, of seasonal influenza vaccine are rare outside North America and Western Europe. Such surveys can provide important information on the progress of national immunization programs and on the awareness of influenza among the general public. We report the results of a survey conducted in 10 countries in Africa, Asia Pacific, Eastern Europe, Latin America and the Middle East that aimed to determine influenza vaccination coverage among adults, the elderly, and children and to find out how influenza is perceived in these regions. Seasonal influenza vaccine coverage varied markedly across countries, and no single factor guaranteed high coverage. Our results indicate that strong recommendations appear insufficient, and that fully funded immunization programs together with high awareness in the population are key to encouraging high influenza vaccination coverage.

The rational use of influenza vaccines in healthy children and children with underlying conditions

PURPOSE OF REVIEW

This review discusses why influenza should be considered an important clinical problem even in healthy children, and what can be expected from the use of influenza vaccines in pediatrics.

RECENT FINDINGS

It has been demonstrated that not only children with an underlying disease but also otherwise healthy children can suffer from severe influenza. The greatest clinical problems arise during the first 23 months of life, but a substantial number of children aged 2-5 years and more than 5 years can die or be hospitalized. This suggests that adequate prophylactic measures should be planned for all children, regardless of their age. An influenza vaccination can be administered using a trivalent inactivated influenza virus or live attenuated influenza virus vaccine, and in both cases seems to be highly cost-effective. However, the actual use of influenza vaccines in children continues to be less than officially recommended.

SUMMARY

Influenza is a clinical problem for children at risk because of underlying disease and previously healthy children. Effective vaccines are currently available, and their extensive pediatric use seems to be associated with significant clinical and socioeconomic advantages.