Invasive meningococcal and pneumococcal disease in Switzerland: cost-utility analysis of different vaccine strategies

Cost-effectiveness of the 15-valent pneumococcal conjugate vaccine for high-risk adults in Switzerland

BACKGROUND

: Vaccination against pneumococcal disease (PD) has shown a favourable cost-effectiveness profile for national immunization programs in multiple countries. While vaccination efforts have concentrated on children, many adults with underlying illnesses face elevated risks of PD and death. A 15-valent pneumococcal conjugate vaccine (V114) is currently available that offers protection against 15 different serotypes and can be used in adults.

RESEARCH DESIGN AND METHODS

: We examined the cost-effectiveness of V114 vaccination in high-risk adults, aged 18+, in Switzerland. To this end, a Markov model was constructed estimating the lifetime direct medical costs and clinical effectiveness of V114 vaccination on invasive pneumococcal disease (IPD) and non-bacteremic pneumococcal pneumonia (NBPP) among high-risk adults.

RESULTS

: Considering 60% vaccine uptake and direct effects of vaccination, in total 760 IPD and 4,396 NBPP in- and outpatient cases could be prevented. Vaccinating high-risk adults with V114 led to CHF 37.4 million additional vaccination costs but saved CHF 14.4 million of medical treatment costs. V114 vaccination produced a gain of 2,095 QALYs and 6,320 LYs compared with no vaccination, leading to incremental cost-effectiveness ratios of CHF 17,866/QALY and CHF 15,616/QALY gained from a health care payer and societal perspective, respectively.

Conclusions: This evidence justifies the implementation of V114 vaccination among high-risk adults in Switzerland.

Economic Evaluation of Selective Neonatal Bacillus Calmette-Guérin Vaccination of High-risk Infants in Ireland

BACKGROUND

In Western Europe, currently only Ireland and Portugal continue to provide universal neonatal bacillus Calmette-Guérin (BCG) vaccination programs, despite not being considered as high tuberculosis (TB) incidence countries. Other European countries only vaccinate infants considered at high risk of contracting TB. We evaluated the cost-effectiveness of selective BCG vaccination compared with strategies of universal and no vaccination.

METHODS

An economic model was used to simulate a cohort from birth to life expectancy, taking the perspective of the publicly funded healthcare system. BCG protection was modeled to last 15 years. International vaccine efficacy data were combined with Irish epidemiologic and cost data. The model took into account long-term sequelae associated with TB meningitis and severe adverse reactions relating to the BCG vaccine. A fully probabilistic model was used to incorporate uncertainty across all parameters.

RESULTS

At &OV0556;139,557 per quality-adjusted life year, selective vaccination was not cost-effective relative to a program of no vaccination. The incremental cost-effectiveness of universal vaccination was &OV0556;2.55 million per quality-adjusted life year relative to selective vaccination. There was substantial uncertainty regarding the effectiveness of BCG vaccination. The cost-effectiveness of selective vaccination could be substantially improved by reducing the cost of administering the vaccine.

CONCLUSIONS

In the absence of changes to other aspects of TB control, a switch to selective vaccination will result in increased cases of childhood TB. Although not considered cost-effective, selective vaccination may be preferable to no vaccination until other changes to TB control may be implemented to reduce the risk of TB in children.

Sources and Characteristics of Utility Weights for Economic Evaluation of Pediatric Vaccines: A Systematic Review

BACKGROUND

Cost-effectiveness analysis of pediatric vaccines for infectious diseases often requires quality-of-life (utility) weights.

OBJECTIVE

To investigate how utility weights have been elicited and used in this context.

METHODS

A systematic review was conducted of studies published between January 1990 and July 2013 that elicited or used utility weights in cost-effectiveness analyses of vaccines for pediatric populations. The review focused on vaccines for 17 infectious diseases and is presented following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) methodology.

RESULTS

A total of 6410 titles and abstracts and 225 full-text articles were reviewed. Of those selected for inclusion (n = 101), 15 articles described the elicitation of utility weights and 86 described economic modeling studies using utilities. Various methods were used to generate utilities, including time trade-off, contingent valuation, and willingness to pay, as well as a preference-based measure with associated value sets, such as the EuroQol five-dimensional questionnaire or the Health Utilities Index. In modeling studies, the source of utilities used was often unclear, poorly reported, or based on weak underlying evidence. We found no articles that reported on the elicitation or use of utilities in diphtheria, polio, or tetanus.

CONCLUSIONS

The scarcity of appropriate utility weights for vaccine-preventable infectious diseases in children and a lack of standardization in their use in economic assessments limit the ability to accurately assess the benefits associated with interventions to prevent infectious diseases. This is an issue that should be of concern to those making decisions regarding the prevention and treatment of infectious childhood illnesses.

Re-evaluating cost effectiveness of universal meningitis vaccination (Bexsero) in England: modelling study

OBJECTIVE

To use mathematical and economic models to predict the epidemiological and economic impact of vaccination with Bexsero, designed to protect against group B meningococcal disease, to help inform vaccine policy in the United Kingdom.

DESIGN

Modelling study.

SETTING

England.

POPULATION

People aged 0-99.

INTERVENTIONS

Incremental impact of introductory vaccine strategies simulated with a transmission dynamic model of meningococcal infection and vaccination including potential herd effects. Model parameters included recent evidence on the vaccine characteristics, disease burden, costs of care, litigation costs, and loss of quality of life from disease, including impacts on family and network members. The health impact of vaccination was assessed through cases averted and quality adjusted life years (QALYs) gained.

MAIN OUTCOME MEASURES

Cases averted and cost per QALY gained through vaccination; programmes were deemed cost effective against a willingness to pay of £20,000 (€25,420, $32,677) per QALY gained from an NHS and personal and social services perspective.

RESULTS

In the short term, case reduction is greatest with routine infant immunisation (26.3% of cases averted in the first five years). This strategy could be cost effective at £3 (€3.8, $4.9) a vaccine dose, given several favourable assumptions and the use of a quality of life adjustment factor. If the vaccine can disrupt meningococcal transmission more cases are prevented in the long term with an infant and adolescent combined programme (51.8% after 30 years), which could be cost effective at £4 a vaccine dose. Assuming the vaccine reduces acquisition by 30%, adolescent vaccination alone is the most favourable strategy economically, but takes more than 20 years to substantially reduce the number of cases.

CONCLUSIONS

Routine infant vaccination is the most effective short term strategy and could be cost effective with a low vaccine price. Critically, if the vaccine reduces carriage acquisition in teenagers, the combination of infant and adolescent vaccination could result in substantial long term reductions in cases and be cost effective with competitive vaccine pricing.

Cost-effectiveness studies of pneumococcal conjugate vaccines

The 7-valent pneumococcal conjugate vaccine is licensed in many countries for the prevention of pediatric pneumococcal disease. The vaccine is known to be highly immunogenic in infants and young children, and has been shown to be efficacious not only in decreasing disease in pediatric age groups but also in adults through herd immunity. Cost-effectiveness analyses of this vaccine have been performed in a number of countries. The present review compiles, summarizes and critiques these analyses. The range of values for cost-effectiveness, as measured in cost per life-years gained, in the studies reviewed, ranges from 14,000 US dollars to 147,000 US dollars with one outlier at 504,000 US dollars. For cost per quality-adjusted life years the range is 26,000 US dollars to 66,000 US dollars. Recommendations for the use of the vaccine will take account not only of these ratios but also of the absolute burden of disease. Performing cost-effectiveness analyses for healthcare interventions in infants and children is one means of redressing inequalities.

Introducing vaccination against serogroup B meningococcal disease: an economic and mathematical modelling study of potential impact

BACKGROUND

Meningococcal disease remains an important cause of morbidity and mortality worldwide. The first broadly effective vaccine against group B disease (which causes considerable meningococcal disease in Europe, the Americas and Australasia) was licensed in the EU in January 2013; our objective was to estimate the potential impact of introducing such a vaccine in England.

METHODS

We developed two models to estimate the impact of introducing a new 'MenB' vaccine. The cohort model assumes the vaccine protects against disease only; the transmission dynamic model also allows the vaccine to protect against carriage (accounting for herd effects). We used these, and economic models, to estimate the case reduction and cost-effectiveness of a number of different vaccine strategies.

RESULTS

We estimate 27% of meningococcal disease cases could be prevented over the lifetime of an English birth cohort by vaccinating infants at 2,3,4 and 12 months of age with a vaccine that prevents disease only; this strategy could be cost-effective at £9 per vaccine dose. Substantial reductions in disease (71%) can be produced after 10 years by routinely vaccinating infants in combination with a large-scale catch-up campaign, using a vaccine which protects against carriage as well as disease; this could be cost-effective at £17 per vaccine dose.

CONCLUSIONS

New 'MenB' vaccines could substantially reduce disease in England and be cost-effective if competitively priced, particularly if the vaccines can prevent carriage as well as disease. These results are relevant to other countries, with a similar epidemiology to England, considering the introduction of a new 'MenB' vaccine.

Cost effectiveness of pediatric pneumococcal conjugate vaccines: a comparative assessment of decision-making tools

BACKGROUND

Several decision support tools have been developed to aid policymaking regarding the adoption of pneumococcal conjugate vaccine (PCV) into national pediatric immunization programs. The lack of critical appraisal of these tools makes it difficult for decision makers to understand and choose between them. With the aim to guide policymakers on their optimal use, we compared publicly available decision-making tools in relation to their methods, influential parameters and results.

METHODS

The World Health Organization (WHO) requested access to several publicly available cost-effectiveness (CE) tools for PCV from both public and private provenance. All tools were critically assessed according to the WHO's guide for economic evaluations of immunization programs. Key attributes and characteristics were compared and a series of sensitivity analyses was performed to determine the main drivers of the results. The results were compared based on a standardized set of input parameters and assumptions.

RESULTS

Three cost-effectiveness modeling tools were provided, including two cohort-based (Pan-American Health Organization (PAHO) ProVac Initiative TriVac, and PneumoADIP) and one population-based model (GlaxoSmithKline's SUPREMES). They all compared the introduction of PCV into national pediatric immunization program with no PCV use. The models were different in terms of model attributes, structure, and data requirement, but captured a similar range of diseases. Herd effects were estimated using different approaches in each model. The main driving parameters were vaccine efficacy against pneumococcal pneumonia, vaccine price, vaccine coverage, serotype coverage and disease burden. With a standardized set of input parameters developed for cohort modeling, TriVac and PneumoADIP produced similar incremental costs and health outcomes, and incremental cost-effectiveness ratios.

CONCLUSIONS

Vaccine cost (dose price and number of doses), vaccine efficacy and epidemiology of critical endpoint (for example, incidence of pneumonia, distribution of serotypes causing pneumonia) were influential parameters in the models we compared. Understanding the differences and similarities of such CE tools through regular comparisons could render decision-making processes in different countries more efficient, as well as providing guiding information for further clinical and epidemiological research. A tool comparison exercise using standardized data sets can help model developers to be more transparent about their model structure and assumptions and provide analysts and decision makers with a more in-depth view behind the disease dynamics. Adherence to the WHO guide of economic evaluations of immunization programs may also facilitate this process. Please see related article: http://www.biomedcentral.com/1741-7007/9/55.

Methodological concerns with economic evaluations of meningococcal vaccines

The evolution of meningococcal vaccines illustrates nicely the incremental technological process that is common to much medical innovation and particularly appropriate to economic analysis. However, the economic evaluation of vaccines is complicated by several features unique to vaccines, including the possibility of indirect (herd immunity) benefits and the shear breadth of vaccination strategies available to decision makers. As with the vaccines themselves, the modelling approaches applied to the economic evaluation of meningococcal vaccines have evolved to become increasingly complex. Despite such innovation, concerns remain about the quality of economic studies of meningococcal vaccines. This article reviews evaluations of meningococcal vaccine strategies in developed countries and provides recommendations for future work in this area. Four potentially problematic areas in the existing literature are identified - indirect costs, herd immunity, quality of life and comparison programmes - and approaches to these issues are discussed. Recommendations for reporting a 'minimum analysis profile' case are also made. Although comparisons across studies are difficult at best, recent work shows that incorporating the indirect benefits and costs of vaccination substantially improves cost effectiveness.

Cost-effectiveness analysis of adding a quadrivalent HPV vaccine to the cervical cancer screening programme in Switzerland

OBJECTIVE

Based on positive safety and efficacy data, a quadrivalent Human PapillomaVirus (HPV) vaccine has been approved in Switzerland to prevent HPV types 6, 11, 16 and 18 infections. The objective of this study was to explore the cost-effectiveness of an HPV vaccination in Switzerland.

DESIGN AND METHODS

A Markov model of the natural history of HPV infection was adapted to the Swiss context and followed a hypothetical cohort of 41,200 girls aged 11 years over their lifetime. Main epidemiological and economic parameters were extracted from the literature. Two strategies were compared: conventional cytological screening only and HPV vaccination followed by conventional cytological screening. A coverage rate of 80% was used and the vaccine was assumed to provide a lifelong protection. Analyses were performed from the direct health care cost perspective including only direct medical costs.

RESULTS

Compared to screening only, adding a quadrivalent HPV vaccine could prevent over lifetime 62% of cervical cancers and related deaths, 19% of Cervical Intraepithelial Neoplasia (CIN 1), 43% of CIN 2, 45% of CIN 3 and 66% of genital warts per cohort. Incremental cost-effectiveness ratios (ICER) were estimated to be CHF 45,008 per Life Year Gained (LYG) and CHF 26,005 per Quality Adjusted Life Year (QALY) gained. Sensitivity analyses demonstrated that the ICER was robust to all parameters, but was most sensitive to the need for a booster and discount rates.

CONCLUSIONS

Compared to commonly accepted standard thresholds in Europe and other vaccination strategies implemented in Switzerland, adding a quadrivalent HPV vaccine alongside the current cervical cancer screening programme is likely to be cost-effective in Switzerland.

Invasive meningococcal disease epidemiology and control measures: a framework for evaluation

BACKGROUND

Meningococcal disease can have devastating consequences. As new vaccines emerge, it is necessary to assess their impact on public health. In the absence of long-term real world data, modeling the effects of different vaccination strategies is required. Discrete event simulation provides a flexible platform with which to conduct such evaluations.

METHODS

A discrete event simulation of the epidemiology of invasive meningococcal disease was developed to quantify the potential impact of implementing routine vaccination of adolescents in the United States with a quadrivalent conjugate vaccine protecting against serogroups A, C, Y, and W-135. The impact of vaccination is assessed including both the direct effects on individuals vaccinated and the indirect effects resulting from herd immunity. The simulation integrates a variety of epidemiologic and demographic data, with core information on the incidence of invasive meningococcal disease and outbreak frequency derived from data available through the Centers for Disease Control and Prevention. Simulation of the potential indirect benefits of vaccination resulting from herd immunity draw on data from the United Kingdom, where routine vaccination with a conjugate vaccine has been in place for a number of years. Cases of disease are modeled along with their health consequences, as are the occurrence of disease outbreaks.

RESULTS

When run without a strategy of routine immunization, the simulation accurately predicts the age-specific incidence of invasive meningococcal disease and the site-specific frequency of outbreaks in the Unite States. 2,807 cases are predicted annually, resulting in over 14,000 potential life years lost due to invasive disease. In base case analyses of routine vaccination, life years lost due to infection are reduced by over 45% (to 7,600) when routinely vaccinating adolescents 12 years of age at 70% coverage. Sensitivity analyses indicate that herd immunity plays an important role when this population is targeted for vaccination. While 1,100 cases are avoided annually when herd immunity effects are included, in the absence of any herd immunity, the number of cases avoided with routine vaccination falls to 380 annually. The duration of vaccine protection also strongly influences results.

CONCLUSION

In the absence of appropriate real world data on outcomes associated with large-scale vaccination programs, decisions on optimal immunization strategies can be aided by discrete events simulations such as the one described here. Given the importance of herd immunity on outcomes associated with routine vaccination, published estimates of the economic efficiency of routine vaccination with a quadrivalent conjugate vaccine in the United States may have considerably underestimated the benefits associated with a policy of routine immunization of adolescents.

Vaccination against meningococcal disease in Europe: review and recommendations for the use of conjugate vaccines

At the end of 2005, six European countries had implemented public immunization campaigns with serogroup C conjugate vaccines, and all had experienced substantial declines in the incidence of serogroup C disease. A quadrivalent ACWY meningococcal vaccine is in use in the USA, but serogroup A is extremely rare in Europe and serogroups Y and W135 are infrequent causes of disease. This paper outlines recommendations on the use of conjugate vaccines in Europe based on the experience with meningococcal C conjugate (MCC) vaccines so far.

Immunization strategies for the control of serogroup C meningococcal disease in developed countries

In developed countries, the epidemiology of serogroup C meningococcal disease is characterized by unpredictable outbreaks and a bimodal distribution of cases, with the highest incidence rate among those below 1 year of age and a second peak in teenagers. Serogroup C meningococcal conjugate vaccines elicit a thymus-dependent immunological response that is already present in young infants and is characterized by the production of protective antibodies and the development of memory. Results from immunogenicity and effectiveness studies indicate that waning of immunity occurs over time, and the protection conferred by vaccination before 1 year of age seems to be shortlived. Very different control strategies have been implemented throughout the world and existing vaccination schedules may not be optimal. A schedule consisting of a first dose around 1 year of age and a second dose around 12 years of age seems to be a very cost-effective option in most epidemiological scenarios.

Economics of rotavirus gastroenteritis and vaccination in Europe: what makes sense?

Rotavirus is a major cause of gastroenteritis in children throughout Europe and the world. In addition to causing morbidity and mortality in children, rotavirus gastroenteritis (RVGE) creates a major economic burden on health care systems and families in Europe. The costs of hospital admissions for RVGE and nosocomial infections generate significant medical treatment costs throughout the region. Less information is available on the costs associated with less severe episodes and the costs borne by families, including lost time from work. The availability of rotavirus vaccines presents an effective opportunity to prevent RVGE and these associated economic costs, as well as providing protection to each child and hence benefiting the child's family. The adoption of rotavirus vaccine by health authorities in Europe will require a comparison of the costs and benefits. Economic evaluations that compare the costs of vaccination to the economic benefits of rotavirus vaccination will provide an estimate of its financial impact on health care systems and society. However, to provide a complete picture, economic evaluations of rotavirus vaccines will need to account for both the reduced costs and the reduced morbidity from prevented RVGE. Cost-effectiveness analyses based on quality-adjusted life years (QALYs) provide a systematic approach for assessing vaccination as a health investment, comparing the incremental costs associated with rotavirus vaccination and the reduced morbidity and mortality. QALYs provide a standardized approach for quantifying and comparing reductions in health-related quality of life and premature mortality. Although methodologic limitations exist in applying the QALY approach to childhood vaccines, their use in cost effectiveness analyses allows decision makers to consider the full health benefits of rotavirus and other vaccines.

Vaccine strategies of meningococcal disease: results of a 10-year population-based study

Invasive meningococcal disease (IMD) is an important cause of morbidity and mortality in children and adults. This study was conducted to determine a possible increase in IMD in recent years with special interest focused on serogroup C disease. From January 1st 1993 to December 31st 2002, IMD was studied in one million residents of Austria. We used active, population-based surveillance data from the Office of Public Health. A total of 126 patients with positive blood and/or cerebrospinal fluid culture or positive swabs for Neisseria meningitidis were studied. The median age of all patients was 9.5 years (range 1 month to 63 years). The average incidence of all IMD subgroups was 1.05 cases per 100,000 person years and was highest in children 0-4 years old (7.08 cases per 100,000 person years) followed by young adults aged 15 to 19 years (4.35 cases per 100,000 person years). Serogroup C IMD occurred in 1.30 cases/100,000 person years in patients aged 0 to 4 years and in 1.92 cases/100,000 person years in patients aged 15 to 19 years. Overall mortality was 11.1%. There was a significant increase (P =0.001) in IMD due to serogroup B disease within the last 10 years. In contrast, serogroup C disease did not increase during the last decade.

CONCLUSION

Currently, we do not recommend mass vaccination against serogroup C disease in Austria, but young adults aged 15 to 19 years display a high incidence of meningococcal C disease. In this age group, vaccination against serogroup C disease should be considered.

Quality-adjusted life-years lack quality in pediatric care: a critical review of published cost-utility studies in child health

OBJECTIVES

Cost-utility analysis in which health benefits are quantified in terms of quality-adjusted life-years (QALYs) has now become the standard type of cost-effectiveness analysis. These studies are potentially influential in determining the extent of funding for particular pediatric interventions, and so their methodologic quality is extremely important. The objective of this study was twofold: first, to critically appraise published cost-utility analyses of interventions in child and adolescent health care in terms of the methods used to derive QALYs and, second, to discuss unresolved methodologic issues that are pertinent to the measurement of QALYs in pediatric populations.

METHODS

A comprehensive search using computerized databases (including Medline, Embase, Econlit, and databases specific to economic evaluation), Web searches, and citation tracking was undertaken to identify cost-utility studies of interventions that were aimed at those who were younger than 16 years and published before April 2004. The methods of individual studies were compared with the recognized published guidelines of the US Panel on Cost-Effectiveness in Health and Medicine and the National Institute for Clinical Excellence in England and Wales, which recommend the use of a generic health state classification system (eg, Health Utility Index, EuroQol-5D), a choice-based valuation method (eg, standard gamble or time trade-off) and preferences of the general public in estimating QALYs. Studies therefore were categorized and evaluated according to the methods used to describe the health state, the valuation technique, and source of preferences.

RESULTS

Fifty-four studies were reviewed, 34 (63%) of which were published in the past 5 years. A generic health status classification instrument was used in 22 (35%) cases; the remainder developed study-specific health state descriptions or elicited preferences directly from patients or proxies. In 3 (5%) cases, sources were unclear. Preference weights were elicited using choice-based techniques in 28 (42%) cases, either as tariffs for health status classification instruments (17 cases) or by directly valuing health state descriptions or patient health (11 cases). Preferences of the general public were used in only 23 (37%) cases. Four studies aggregated QALYs for mother/child or parents/child pairs without giving any theoretical justification. Although there was an increasing tendency for studies to use generic health status classification instruments, choice-based methods, and preferences of the general public, the majority of studies still did not adhere to these standard recommendations even in the period between January 2000 and March 2004. Despite increasing standardization in the methods advocated for economic evaluation over the past 10 years, there remains extensive variation in the actual methods used by researchers to calculate QALYs for children and adolescents. It is unclear whether these results suggest poor practice or a set of positive (or reactive) choices made by analysts in a methodologically uncertain area in which specific guidance is lacking regarding how to address the complexities of pediatric outcomes within the QALY framework. Many aspects of QALY measurement in children are not yet fully developed. In particular, there is (1) a lack of appropriate health state classification instruments that take account of the dynamics of child development, (2) a lack of health state classification instruments for use in children and infants who are younger than 5 years, and (3) the need to understand fully the role of proxies for measuring and valuing child health. Additional research efforts are also required to develop methods that account for the health benefits of parents or caregivers of the child and to consider the implications of combining different forms of utility measurement in childhood and adulthood.

CONCLUSIONS

Although variations from standard recommendations may be attributable to poor practice among researchers who are either unaware of these recommendations or choose not to follow them, they could equally be the result of attempts to make research more rigorous and more defensible than it might be if the standard recommendations were followed. There are 4 potential approaches to conducting cost-utility analysis in pediatric populations: (1) the explicit development of a generic instrument designed to be applicable across both child and adult populations (likely to be difficult in practice), (2) insistence on use of a generic instrument developed for adults, (3) the use of generic instruments specifically developed for children without being concerned about comparability with interventions aimed at adults, and (4) abandoning attempts to use single outcome measures that combine mortality with quality weights. In the absence of a clear way forward, it is suggested that an expert panel be convened to debate and further consider these potential solutions and recommendations for best practice and future research. In the interim, comparisons of the relative cost-effectiveness reported as cost per QALY gained across interventions for different diseases and populations should be treated with extreme caution.

Meningococcal polysaccharide-protein conjugate vaccines

It is now 5 years since the UK became the first country to introduce the serogroup C meningococcal polysaccharide-protein conjugate vaccines (MenC) into its routine immunisation schedule. This article reviews the global use of MenC with particular reference to the range of immunisation strategies used internationally. To date, concerns that MenC may result in an increase in meningococcal disease due to non-C serogroups have not been realised. The vaccine has proved to be highly safe and effective; however, concerns have arisen regarding the duration of vaccine effectiveness. Although booster doses of MenC may potentially extend the duration of protection offered by the vaccine, there are, as yet, no studies assessing this option. Clinical trials are underway to assess new combination conjugate vaccines (containing A, C, Y, and W polysaccharides), and it is probable that these more broadly protective vaccines will become available in the near future.

Meningococcal vaccines

Meningococcal disease is one of the most feared and serious infections in the young and its prevention by vaccination is an important goal. The high degree of antigenic variability of the organism makes the meningococcus a challenging target for vaccine prevention. Meningococcal polysaccharide vaccines against serogroup A and C are efficacious and have been widely used, often in combination with serogroup Y and W135 components. Their relative lack of immunogenicity in young children and infants can be overcome by conjugation to a protein carrier. The effectiveness of serogroup C glycoconjugate vaccines in children of all ages has been demonstrated and they have now been introduced into routine vaccination schedules. Conjugate vaccines against other serogroups, including A, Y, and W135 will soon be available and it is hoped they may emulate this success. Prevention of serogroup B disease has proven more elusive. Several serogroup B vaccines based on outer membrane vesicles have been shown to be immunogenic and reasonably effective in adults and older children, but the protection offered by them is chiefly strain-specific. Multivalent recombinant PorA vaccines have been developed to broaden the protective effect, but no efficacy data are available as yet. Intensive efforts have been directed at other outer membrane protein vaccine candidates and lipopolysaccharide, and some of these have been shown to offer protection in experimental animal models. Nonpathogenic Neisseriae spp. such as Neisseria lactamica are also possible vaccine candidates. Previously unknown proteins have been identified from in silico analysis of the meningococcal genome and their vaccine potential explored. However, none of these has yet been presented as the 'universal' protective antigen and work in this field continues to be held back by our limited knowledge concerning the mechanisms of natural protection against serogroup B meningococci.

The role of economic evaluation in vaccine decision making: focus on meningococcal group C conjugate vaccine

In recent years, several countries have experienced increases in the incidence of serogroup C meningococcal disease. It can be controlled with older polysaccharide vaccines and particularly the recently developed conjugate vaccines. For 21 developed countries, we investigated the role that economic evaluation played in the decision to introduce the conjugate vaccine into either the routine childhood vaccination schedule, as a mass vaccination 'catch-up' campaign or not at all. A literature review was performed and experts from these countries were contacted. For six countries, we identified published economic evaluations for meningococcal C conjugate vaccination. In four of them (Australia, Canada [Quebec], The Netherlands and the UK) the analyses were performed before a decision about the use of the conjugate vaccine was made. In all of these countries, the economic evaluation offered guidance as to the most efficient way to add the conjugate vaccine to the routine infant immunisation schedule and, in three countries, this advice was adopted by decision makers. In Portugal and Switzerland, initial vaccination decisions were made without the economic evaluations that are influencing current decision making. Of the countries without economic evaluations, six implemented vaccination programmes. Overall, there was a positive correlation between the reported incidence of meningococcal C disease and (a) the decision to vaccinate and (b) performing an economic evaluation. All economic evaluations were modelling studies. The reported cost-effectiveness ratios were sensitive to the age of vaccination, the future meningococcal incidence, vaccine price and some methodological characteristics that varied widely between studies making direct comparisons difficult. In conclusion, in almost all countries where economic evaluations for meningococcal C conjugate vaccinations have been conducted, their results had an important role in the decision-making process. However, in most countries with strongly increasing meningococcal incidence, public health considerations took precedence. In order to improve the international comparability of such studies, firmer national and international modelling guidelines and better adherence to such guidelines seem necessary.

Evaluating health-related quality-of-life studies in paediatric populations: some conceptual, methodological and developmental considerations and recent applications

Although numerous paediatric-based health-related quality-of-life (HR-QOL) instruments are currently in use, there still remain conceptual, methodological and developmental issues to address. This paper provides an up-to-date critical review of the HR-QOL literature in paediatric medicine. Our analysis indicates that there is no consensus on how HR-QOL and overall QOL should be defined and measured in children. It is recommended that future studies focus on operationalising and distinguishing these constructs from each other and from traditional health-status measures. A clear empirical basis for generating instrument items and for prioritising specific domains must be described. Researchers should consider using the data gathered during their first interviews as a springboard from which to test their ideas of HR-QOL and QOL, reformulate concepts and subsequently retest their notions before developing instruments. Related to methodological challenges, consistency and agreement are still used interchangeably when comparing child and parent reports of children's HR-QOL. The Pearson correlation is a measure of co-variation in scores, and not a measure of agreement. We recommend that researchers focus on determining agreement as opposed to consistency. Few, if any, attempts have been made to account for the possibility that a response shift may have occurred in the evaluation of HR-QOL. Most studies have compared HR-QOL scores of children with illness with their healthy peers. As such, there is a dearth of knowledge regarding the normative process of adaptation within the context of illness. It is recommended that researchers focus on gathering data using a relative standard of comparison. We further recommend that researchers interpret HR-QOL data in line with their intended purpose. Regarding developmental consideration, particular attention ought to be paid to developing instruments that consider children's emerging sense of self, cognitive capacity and emotional awareness. Instruments that include items that are age appropriate are more likely to maximise reliability and validity of reports. The results of many HR-QOL instruments are applied in pharmacotherapeutic and pharmacoeconomic assessments. However, there has been relative infrequent application of economically valid HR-QOL tools (utility scales) and the use of HR-QOL scales as outcome measures in paediatric drug trials. As such, few cost-utility analyses have been performed to inform paediatric decision making. In addition, many of the concerns in the development of HR-QOL instruments should also be applied to the utility scales such that they reflect adequately children's preferences for health states.

Pneumococcal conjugate vaccines for preventing vaccine-type invasive pneumococcal disease and pneumonia with consolidation on x-ray in children under two years of age

BACKGROUND

Pneumonia, most commonly caused by Streptococcus pneumoniae (Pnc), is a major cause of morbidity and mortality among young children especially in developing countries. Recently, the prevalence of antibiotic-resistant Pnc has increased worldwide such that the effectiveness of preventive strategies, like the new pneumococcal conjugate vaccines (PCV) on rates of invasive pneumococcal disease (IPD) and pneumonia, needs to be evaluated.

OBJECTIVES

To determine the efficacy of PCV in reducing the incidence of IPD due to vaccine serotypes (VT) and x-ray confirmed pneumonia with consolidation of unspecified etiology in children who received PCV before 12 months of age.

SEARCH STRATEGY

We searched the following databases: the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, Issue 1 2004), MEDLINE (1990 to March 2004) and EMBASE (1990 to December 2003). Reference list of articles, and books of abstracts of relevant symposia, were hand searched. Researchers in the field were also contacted.

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing PCV with placebo, or another vaccine, among children below two years with IPD and clinical/radiographic pneumonia as outcomes.

DATA COLLECTION AND ANALYSIS

Two reviewers independently identified eligible studies, assessed trial quality, and extracted data. Differences were resolved by discussion. The inverse variance method was used to pool effect sizes.

MAIN RESULTS

We identified four trials assessing the efficacy of PCV in reducing the incidence of IPD, two on x-ray confirmed pneumonia as outcome, and one on clinical pneumonia, with or without x-ray confirmation. Results from pooling HIV-1 negative children from the South African study with the other studies were as follows: the pooled vaccine efficacy (VE) for vaccine-type IPD was 88% (95% confidence interval (CI) 73% to 94%; fixed effect and random effects models), the effect measure was statistically significant (p <0.00001) and there was no heterogeneity (p = 0.77I2 0%); the pooled VE for all-serotype IPD was 66% (95% CI 46% to 79%; fixed effect model), the effect measure was statistically significant (p <0.00001) and there was no statistical heterogeneity (p = 0.09, I2 51%); the pooled VE for x-ray confirmed pneumonia was 22% (95% CI 11% to 31%; both fixed effect and random effects models) and there was no statistical heterogeneity (p = 0.80, I2 0%). Analyses that included all the children in the South African study (HIV-1 negative and HIV-1 positive children) and pooled with data from the other studies gave very similar results.

REVIEWERS' CONCLUSIONS

PCV is effective in reducing the incidence of IPD from all serotypes but exerts a greater effect in reducing VT IPD. Although PCV is also effective in reducing the incidence of x-ray confirmed pneumonia, there are still uncertainties about the definition of this outcome. Additional randomised controlled trials are currently in progress.