Complications and sequelae of meningococcal disease in Quebec, Canada, 1990-1994

Comparative long-term adverse effects elicited by invasive group B and C meningococcal infections

BACKGROUND

Given the identity between Neisseria meningitidis serogroup B (MenB) capsular polysaccharide (polysialic acid; PSA) and PSA found on neural cell adhesion molecules, it has been proposed that infection with MenB or vaccination with PSA may be associated with subsequent autoimmune or neurological disease.

METHODS

We conducted 2 studies. The first was a retrospective nationwide study of invasive meningococcal disease (IMD) in Iceland (with 541 subjects) during the period 1975-2004, and we cross referenced this cohort with databases with respect to subsequent diagnosis of autoimmune disorders. A follow-up study involving 120 survivors of IMD was performed. The study included 70 patients with a history of MenB and 50 patients with N. meningitidis serogroup C (MenC) infection, who served as control subjects. Participants answered standardized questionnaires (Beck's Depression Inventory [BDI] II, Depression Anxiety Stress Scales [DASS], and Patient Health Questionnaire [PHQ]), and serum levels of immunoglobulin (Ig) G against MenB and MenC capsular polysaccharides were measured.

RESULTS

The nationwide cohort had 9166 patient-years of follow up. No evidence of increased autoimmunity was found to be associated with MenB, compared with MenC. In the follow-up study, patients were evaluated 16.6 years after the infection, representing 2022 patient-years of observation. Comparable rates of most complications were recorded, but MenC infections were associated with arthritis (P = .008) and migraine headaches (P = .01) more frequently than were MenB infections. No difference was observed with respect to scores on BDI-II, DASS, or PHQ. IgG anti-MenB and anti-MenC capsular polysaccharide levels were not related to patient complaints.

CONCLUSIONS

This study does not support the hypothesis that MenB infection may predispose to autoimmunity. MenC infections are associated with a higher prevalence of arthritis and migraine headaches. No evidence of antibody-associated pathology was detected at long-term follow-up.

Effectiveness of a vaccination programme for an epidemic of meningococcal B in New Zealand

New Zealand has experienced a prolonged epidemic of meningococcal B disease since 1991. The epidemic has waned significantly since its most recent peak in 2001. A strain-specific vaccine, MeNZB, was introduced to control the epidemic in 2004, achieving 81% coverage of people under the age of 20. The vaccine was rolled out in a staged manner allowing the comparison of disease rates in vaccinated and unvaccinated individuals in each year. Vaccine effectiveness in people aged under 20 years is estimated using a Poisson regression model in the years 2001-2008, including adjustments for year, season, age, ethnicity, region and socioeconomic status. Further analyses investigate the dose response relationship, waning of the vaccine effect after one year, and cross-protection against other strains of meningococcal disease. The primary analysis estimates MeNZB vaccine effectiveness to be 77% (95% CI 62-85) after 3 doses and a mean follow-up time of 3.2 years. There is evidence for a protective effect after 2 doses 47% (95% CI 16-67), and no evidence for a waning of effectiveness after one year. Simultaneous modelling of invasive pneumococcal disease and epidemic strain meningococcal B suggests a degree of residual confounding that reduces the effectiveness estimate to 68%. There is evidence for some cross-protection of MeNZB against non-epidemic strains. The MeNZB vaccine was effective against the New Zealand epidemic strain of meningococcal B disease. Between July 2004 and December 2008 an estimated 210 epidemic strain cases (95% CI 100-380), six deaths and 15-30 cases of severe sequelae were avoided in New Zealand due to the introduction of the MeNZB vaccine.

Profile of serogroup Y meningococcal infections in Canada: Implications for vaccine selection

Canada is a leader in establishing routine infant immunization programs against meningococcal C disease. Currently, all provinces have routine programs to provide meningococcal C conjugate vaccines to infants and children. The result of the existing programs has been a decrease in serogroup C incidence. The second most common vaccine-preventable serogroup in Canada is serogroup Y, the incidence of which has been stable. The availability of a quadrivalent conjugate vaccine against serogroups A, C, Y and W135 focuses attention on serogroup Y disease as it becomes relatively more prominent as a cause of vaccine-preventable invasive meningococcal disease. This vaccine was licensed in November 2006 but is not routinely used except in Nunavut, New Brunswick and Prince Edward Island. To allow a better understanding of the 'value added' by a serogroup Y-containing vaccine, it is necessary to have a contemporary profile of Y disease in Canada. In the present paper, recent surveillance data on invasive meningococcal disease across Canada are summarized.

WITHDRAWN: Conjugate vaccines for preventing meningococcal C meningitis and septicaemia

BACKGROUND

Meningococcal polysaccharide (MPLS) vaccines protect against Serogroup C disease, but do not produce an immune response in infants less than two years of age. This limitation can be overcome by linking C polysaccharide to carrier proteins ('conjugating'), to create meningococcal serogroup C conjugate (MCC) vaccines. In the absence of trial data, the immune response to vaccination has been considered to be a reasonable surrogate for vaccine protection.

OBJECTIVES

To assess the immunogenicity, safety and efficacy of MCC vaccines for preventing meningitis and septicaemia.

SEARCH STRATEGY

We searched the Cochrane Central Register Controlled Trials (CENTRAL) (The Cochrane Library 2005, issue 3); MEDLINE (1966 to September, Week 1 2005); and EMBASE (1990 to June 2005) and references of studies.

SELECTION CRITERIA

Randomised controlled trials (RCTs) and controlled clinical trials (CCTs) in humans comparing MCC vaccines against a control vaccine or none. In the absence of any trials on vaccine efficacy, population-based observational studies about effectiveness were included.

DATA COLLECTION AND ANALYSIS

Two authors independently screened the results of the literature searches, selected eligible studies, extracted the data and evaluated the quality of them.

MAIN RESULTS

The studies showed that MCC vaccine was highly immunogenic in infants after two and three doses, in toddlers after one and two doses and in older age groups after one dose. In general higher titres were generated after MCC than after MPLS vaccines. Immunological hypo-responsiveness seen after repeated doses of MPLS vaccine may be overcome with MCC. Observational studies have documented a significant decline in meningococcal C disease in countries where MCC vaccines have been widely used. The timing of the vaccinations schedules, the specific conjugate used, and the vaccines given concomitantly or combined, may be important.

AUTHORS' CONCLUSIONS

The MCC vaccine appears to be safe, immunogenic and able to induce immunological memory in all age groups. Observational studies strongly suggest that MCC is clinically effective.

Meningococcal glycoconjugate vaccines

Neisseria meningitidis is a major cause of invasive bacterial infections worldwide. For this reason, efforts to control the disease have been directed at optimizing meningococcal vaccines and implementing appropriate vaccination policies. In the past, plain polysaccharide vaccines containing purified capsular polysaccharides A, C, Y and W135 were developed, but failed to protect infants, who are at greatest risk. Experience with the conjugate Haemophilus vaccine suggested that this approach might well empower meningococcal vaccines. Thus, a very efficacious vaccine against serogroup C Neisseria meningitis was optimized and has been widely used in developed nations since 1999. On the basis of epidemiological changes in the circulation of pathogenic serogroups in the United States, a quadrivalent conjugate vaccine against A, C, Y and W135 serogroups (Menactra™) has been developed and was approved by the U.S. FDA (Food and Drug Administration) in 2005. Recently, another tetravalent conjugate meningococcal vaccine (Menveo™) has been licensed and made available in the United States of America and in the European Union. Finally, in response to large epidemics caused by serogroup A meningococcus in Africa, a new, safe, immunogenic and affordable vaccine has been developed. This review highlights the evolution of conjugate meningococcal vaccines in general and discusses how this kind of vaccine can contribute to preventing meningococcal disease.

Surviving meningococcal septic shock in childhood: long-term overall outcome and the effect on health-related quality of life

Introduction

The purpose of this study was to evaluate associations between long-term physical and psychological outcome variables in patients who survived meningococcal septic shock (MSS) in childhood.

Methods

The study population was made up of all MSS patients requiring intensive care treatment between 1988 and 2001.

Results

A total of 120 patients visited the follow-up clinic (age at paediatric intensive care unit (PICU) admission 3.1 years; follow-up interval 9.8 years; age at follow-up 14.5 years (all medians)). Four major outcomes were considered: 1) major physical sequelae (defined as major scars and/or orthopaedic sequelae) (29/120), 2) mild neurological impairments (39/120), 3) problem behaviour (defined as a total score above the 90^th percentile of the reference groups on questionnaires to screen for psychopathology) (16/114) and 4) total intelligence quotient < 85 (18/115). No differences were found between patients with major physical sequelae and patients without major physical sequelae as to the presence of problem behaviour or total IQ < 85. Also, no differences were found between patients with mild neurological impairments and patients without as to the presence of problem behaviour or total IQ < 85. Finally, no differences were found between patients with major physical sequelae and patients without as to the presence of mild neurological sequelae. Less favourable scores on behavioural and emotional problems were significantly associated with poorer health-related quality of life (HR-QoL). HR-QoL scores were to a lesser amount predicted by severity of illness at time of PICU admission or by adverse physical outcome.

Conclusions

Long-term adverse physical and psychological outcomes in survivors of MSS did not seem to be associated. Poorer HR-QoL was mainly predicted by problem behaviour.

Optimizing protection against meningococcal disease

Neisseria meningitidis is a leading cause of bacterial meningitis and septicemia in the United States. Vaccines directed against meningococcal disease must elicit high and persistent titers of bactericidal antibodies against prevalent meningococcal serogroups and be highly efficacious in preventing meningococcal infection. Currently, 2 quadrivalent (A, C, W-135, Y) vaccines-a polysaccharide meningococcal vaccine and a conjugate meningococcal vaccine-are licensed in the United States. Neither is approved for use in infants or toddlers younger than 2 years of age. Results of studies with an investigational quadrivalent (ACWY) meningococcal CRM(197) glycoconjugate vaccine in infants demonstrate that this vaccine has potential to protect this age group. The availability of an effective vaccine for routine universal infant immunization is particularly important because the incidence of invasive meningococcal disease is greatest in infants for all serogroups and because achievable vaccination rates are much greater for infants and young children than they are for adolescents.

Global and regional risk of disabling sequelae from bacterial meningitis: a systematic review and meta-analysis

Few data sources are available to assess the global and regional risk of sequelae from bacterial meningitis. We aimed to estimate the risks of major and minor sequelae caused by bacterial meningitis, estimate the distribution of the different types of sequelae, and compare risk by region and income. We systematically reviewed published papers from 1980 to 2008. Standard global burden of disease categories (cognitive deficit, bilateral hearing loss, motor deficit, seizures, visual impairment, hydrocephalus) were labelled as major sequelae. Less severe, minor sequelae (behavioural problems, learning difficulties, unilateral hearing loss, hypotonia, diplopia), and multiple impairments were also included. 132 papers were selected for inclusion. The median (IQR) risk of at least one major or minor sequela after hospital discharge was 19.9% (12.3-35.3%). The risk of at least one major sequela was 12.8% (7.2-21.1%) and of at least one minor sequela was 8.6% (4.4-15.3%). The median (IQR) risk of at least one major sequela was 24.7% (16.2-35.3%) in pneumococcal meningitis; 9.5% (7.1-15.3%) in Haemophilus influenzae type b (Hib), and 7.2% (4.3-11.2%) in meningococcal meningitis. The most common major sequela was hearing loss (33.9%), and 19.7% had multiple impairments. In the random-effects meta-analysis, all-cause risk of a major sequela was twice as high in the African (pooled risk estimate 25.1% [95% CI 18.9-32.0%]) and southeast Asian regions (21.6% [95% CI 13.1-31.5%]) as in the European region (9.4% [95% CI 7.0-12.3%]; overall I(2)=89.5%, p<0.0001). Risks of long-term disabling sequelae were highest in low-income countries, where the burden of bacterial meningitis is greatest. Most reported sequelae could have been averted by vaccination with Hib, pneumococcal, and meningococcal vaccines.

Quadrivalent meningococcal vaccines: hyporesponsiveness as an important consideration when choosing between the use of conjugate vaccine or polysaccharide vaccine

Regional variations in the incidence and the distribution of serogroups which are responsible of meningococcal disease necessitate multivalent vaccines to ensure broad coverage for travelers. For almost 30 years, this has been provided by quadrivalent polysaccharide vaccine to protect against serogroups A, C, W-135 and Y, but with the advent of quadrivalent conjugate vaccines is there still a case to use the polysaccharide? The well documented hyporesponsiveness induced by polysaccharide vaccines after repeated administration, most clearly observed against serogroup C, suggest that, where available, conjugate vaccines should always be considered ahead of polysaccharide vaccine.

Safety and immunogenicity of an investigational quadrivalent meningococcal conjugate vaccine after one or two doses given to infants and toddlers

With the emergence of multiple meningococcal serogroups in different geographic areas, broad vaccine protection from infancy is desirable. One hundred and seventy-five infants received either two doses of a meningococcal quadrivalent (A, C, W-135, Y) conjugate vaccine (MenACWY-CRM) at 6 and 12 months, one dose of MenACWY-CRM at 12 months, or MenC at 12 months and MenACWY-CRM at 18 months. Bactericidal antibody titers using human complement were measured before and 1 month after each dose. Injection-site reactions were reported by 22-45% of participants following MenACWY-CRM given at 6 or 12 months. Similar proportions of subjects had injection-site reactions following two doses of MenACWY-CRM (32-41%) or one dose of MenC (26-44%). The incidence of systemic adverse events was comparable between groups. After two doses of MenACWY-CRM, the percentages of participants reporting hSBA titers >or=8 were 100% for C, W-135, and Y, and 84% for A. Serogroup C titers were more than 10-fold higher after two doses of MenACWY-CRM than after one dose of MenC or MenACWY-CRM at 12 months. Serogroup C titers were comparable following a single dose of MenACWY-CRM or MenC at 12 months. MenACWY-CRM is well tolerated and immunogenic given at 12 months, or two doses at 6 and 12 months of age.

Outcomes of meningococcal disease in adolescence: prospective, matched-cohort study

OBJECTIVE

We examined the physical, cognitive, educational, social, and psychological outcomes of invasive meningococcal disease in adolescence, as well as demographic and disease factors associated with outcomes.

METHODS

A population-based, matched-cohort study was performed. A total of 101 gender- and age-matched case-control pairs (15-19 years of age at the time of disease; 46% male) from 6 regions of England underwent follow-up evaluations 18 to 36 months after invasive meningococcal disease. Educational, social, and vocational function, mental health, social support, self-efficacy, and quality-of-life data were collected by using standardized questionnaires and neuropsychological tests.

RESULTS

Fifty-seven percent of case subjects (n = 58) had major physical sequelae. Survivors had greater depressive symptoms, greater fatigue, less social support, greater reduction in quality of life, and lower educational attainment compared with control subjects. Survivors with serogroup C disease had greater physical sequelae than did those with serogroup B disease. Greater cognitive deficits were associated with younger age at diagnosis. Only 53 of 101 case subjects reported any medical follow-up care after invasive meningococcal disease.

CONCLUSIONS

Survivors of invasive meningococcal disease in adolescence have a disturbing series of deficits, including poorer physical and mental health, quality of life, and educational achievement. Serogroup C is associated with poorer outcomes. Invasive meningococcal disease attributable to serogroup B disease remains a major cause of morbidity and death among adolescents. Medical care is poor after discharge from the hospital. Routine follow-up care of adolescent survivors may prevent or ameliorate physical and psychosocial morbidity after invasive meningococcal disease.

Rapid identification of herd effects with the introduction of serogroup C meningococcal conjugate vaccine in Ontario, Canada, 2000-2006

In 2001, Canada's National Advisory Committee on Immunization endorsed a meningococcal serogroup C conjugate vaccine, which appears to provide durable serogroup-specific immunity while reducing nasopharyngeal carriage. With reference to direct and indirect effects on case occurrence, we sought to evaluate recent trends in the incidence of invasive meningococcal disease (IMD) in Ontario. Analyses included all IMD cases reported between 2000 and 2006 to the Ontario Central Public Health Laboratory. Poisson models incorporating terms for age, sex and seasonal oscillation identified a significant downward trend in disease occurrence, which was strongest in serogroup C cases and not evident when serogroup C strains were excluded from the analysis. Among age groups not targeted by the vaccine program serogroup C, IMD displayed a pattern of decreasing incidence that was not present in non-serogroup C disease. These apparent dramatic effects of conjugate C vaccine (both direct and indirect) may be important in the implementation and evaluation of vaccine policy in other jurisdictions.

Improved survival of children with sepsis and purpura: effects of age, gender, and era

Background

To gain insight into factors that might affect results of future case-control studies, we performed an analysis of children with sepsis and purpura admitted to the paediatric intensive care unit (PICU) of Erasmus MC-Sophia Children's Hospital (Rotterdam, The Netherlands).

Methods

Between 1988 and 2006, all 287 children consecutively admitted with sepsis and purpura were included in various sepsis studies. Data regarding age, gender, ethnicity, serogroup of Neisseria meningitidis, severity, therapy, and survival were collected prospectively. These data were pooled into one database and analyzed retrospectively.

Results

The case fatality rate (CFR) from sepsis and purpura was 15.7%. During the study period, survival improved significantly. Younger age was significantly associated with more severe disease and a higher CFR. Children under the median age of 3.0 years had an increased risk of case fatality (odds ratio 4.3, 95% confidence interval 2.1 to 9.2; p < 0.001). Gender was not associated with CFR. However, males did have higher Paediatric Risk of Mortality scores, fewer PICU-free days, and more presence of shock. The course of sepsis and purpura was not related to ethnic origin. A causative organism was isolated in 84.3% of cases. N. meningitidis was the major organism (97.5%). Although N. meningitidis serogroup B was observed more often in younger children, serogroups were not associated with severity or survival. During the study period, the use of inotropic agents and corticosteroids changed substantially (less dopamine and more dobutamine, norepinephrine, and corticosteroids).

Conclusion

Age and gender are determinants of severity of paediatric sepsis and purpura. Survival rates have improved during the last two decades.

Self-esteem in children and adolescents after septic shock caused by Neisseria meningitidis: scars do matter

PURPOSE

To investigate self-esteem and its relation to scars, amputations, and orthopedic sequelae in children and adolescents long term after meningococcal septic shock (MSS) caused by Neisseria meningitidis.

METHODS

The Dutch versions of the Self-Perception Profile for Children (SPP-C; 8-11 years) and the Self-Perception Profile for Adolescents (SPP-A; 12-17 years) were used to assess self-esteem. The Patient and Scar Assessment Scale (PSAS) was used to evaluate scar severity.

RESULTS

MSS boys aged 8-11 years achieved higher, more favorable scores on self-esteem, whereas same-aged MSS girls reported comparable levels of self-esteem compared with the respectively same-aged reference boys and girls. MSS boys and girls aged 12-17 years obtained unfavorable scores on self-esteem compared with respectively same-aged reference boys and girls. Overall gender did not have an effect on self-esteem. Severity of illness, age at time of illness, and age at time of follow-up were not significant predictors of self-esteem. MSS adolescents with scars reported lower global self-worth than MSS adolescents without scars. The worse MSS children evaluated their scars, the worse their outcomes on social acceptance. The worse MSS adolescents evaluated their scars, the worse their outcomes on close friendship, but the better their outcomes on social acceptance and behavioral conduct.

CONCLUSION

In this cross-sectional study, favorable outcomes for self-esteem were found in MSS children, whereas MSS adolescents reported lower self-esteem compared with reference adolescents. Adolescents with scars reported lower global self-worth than MSS adolescents without scars.

Surviving meningococcal septic shock: health consequences and quality of life in children and their parents up to 2 years after pediatric intensive care unit discharge

OBJECTIVE

To assess health consequences and health-related quality of life (HR-QoL) in children with meningococcal septic shock up to 2 yrs after discharge from the pediatric intensive care unit and to assess their parents. To determine major predictors of that outcome.

PATIENTS AND METHODS

A prospective cohort study. Follow-up of all consecutive children with septic shock and purpura requiring intensive care treatment between 2001 and 2005, and their parents. HR-QoL was assessed with the Child Health Questionnaire (children) and Medical Outcomes Study 36-item Short-Form Health Survey (parents).

RESULTS

Of 53 eligible families, 47 participated (28 boys/19 girls; median age at the time of pediatric intensive care unit admission, 3.7 yrs; median Pediatric Risk of Mortality score, 21). A total of 26 children (55%) had scars as a result of skin necrosis; two (4%) had amputation of a digit or digits. In 21 children (45%), chronic complaints were reported. Children with and without chronic complaints did not differ significantly with regard to severity of illness and age at the time of pediatric intensive care unit admission. Significantly lower scores were found on HR-QoL scales concerning mainly physical functioning and health perception in comparison with normative data. There was a significant negative association between severity of illness and the HR-QoL scale concerning physical functioning. Children with chronic complaints had significantly lower scores on the HR-QoL scale concerning pain. Eight of 47 mothers (17%) at the time of the study had anxiety or depression requiring professional help. Mothers with and without these problems differed significantly with regard to age of their child at the time of pediatric intensive care unit admission. Parents showed significantly higher scores on HR-QoL scales concerning physical functioning and bodily pain in comparison with normative data. There was a significantly negative association between the presence of emotional problems and HR-QoL scores in mothers.

CONCLUSIONS

Up to 2 yrs after discharge from the pediatric intensive care unit, there is still a considerable effect on health and HR-QoL in children, especially on the physical scales. Severity of illness and chronic complaints negatively affected HR-QoL scales in children. Quite a few mothers suffered from emotional problems.

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.

Doença meningocócica: comparação entre formas clínicas

Visando avaliar formas clínicas da doença meningocócica, foram revistos 201 casos diagnosticados como doença meningocócica, em Hospital Universitário da Universidade Federal Fluminense; durante o período de 1971 a 1996, dos quais 185 preencheram os critérios de inclusão. A caracterização clínico-laboratorial permitiu reagrupá-los nas formas de doença meningocócica com meningite, 18%, meningite e septicemia, 62%, e septicemia, 20%. Dados epidemiológicos disponíveis não diferenciaram formas clínicas. Na meningite meningocócica foi significativamente maior: tempo de história clínica; freqüência de manifestações neurológicas; e positividade da bacterioscopia, cultura e teste do látex no líquor. Na septicemia menigocócica, houve predomínio significativamente de: choque; letalidade e níveis maiores de tempo parcial de tromboplastina. Septicemia meningogócica e septicemia com meningite se diferenciaram da meningite meningocócica quanto a: tempo de história clínica; ocorrência de sinais neurológicos focais; coagulação intravascular disseminada e artrite. Dados clínico-laboratoriais levam a admitir meningite como forma localizada de doença meningocócica, e septicemia com meningite e septicemia como variações de gravidade da forma sistêmica da doença.

Vaccinating adolescents against meningococcal disease in Canada: a cost-effectiveness analysis

BACKGROUND

One dose of serogroup C meningococcal conjugate vaccine (MCV-C) at 12 months of age is the most common immunization schedule in Canada, but immunity may wane over time.

OBJECTIVES

To assess the cost-effectiveness of a booster dose at 12 years of age with either MCV-C or a quadrivalent ACYW135 meningococcal conjugate vaccine (MCV-4).

METHODS

A simulation model for assessing both the direct and indirect effects of vaccination was developed. Age- and serogroup-specific incidence and fatality rates were derived from Canadian surveillance data. Vaccine efficacy was estimated from data from the U.K. and Spain, assuming an age-dependent decline of vaccine efficacy over time. Expected vaccine coverage rates were 90% at 12 months, and 70% at 12 years. Herd immunity was modeled using UK data. Vaccine purchase price per dose was $23 for MCV-C and $70 for MCV-4. Costs and health outcomes were discounted at 3% per year. Results, expressed in 2004 Canadian $ and from a societal perspective, were presented for a steady state situation and a population of 1 million.

RESULTS

Under the "no vaccination" base scenario, 5.7 cases of vaccine-preventable meningococcal disease would occur each year. Vaccination at 12 months using MCV-C would reduce the burden of disease by 32%. Adding MCV-C at 12 years of age would reduce the number of cases by 55% at no marginal cost, while using MCV-4 would result in a disease reduction of 78% for a marginal cost of $31000 per QALY gained. Comparing MCV-4 with MCV-C as a booster dose, the incremental cost-effectiveness ratio would be $113000 per QALY. The efficacy of C-MCV vaccination at 12 months and the differential price between the two vaccines were the parameters having the strongest impact on the cost/QALY ratios. Any increase in the incidence of serogroup Y will improve the marginal cost-effectiveness ratio associated with MCV-4.

CONCLUSION

Adolescent revaccination would be beneficial. Using C-MCV would be the most cost-effective option, while using MCV-4 would be more effective but would also require more investment.

IS1301 fingerprint analysis of Neisseria meningitidis strains belonging to the ET-15 clone

Meningococci of the ET-15 clone frequently cause clusters of invasive meningococcal disease (IMD) and are associated with a high case-fatality ratio. Timely typing of strains from outbreaks of IMD caused by this clone is hampered by the low variability of its surface antigens. We present a new Southern blot-based typing method for ET-15 meningococci based on the insertion element IS1301, which was present in all 70 ET-15 strains tested. Fingerprints were stable in vitro over a period of 100 days of cultivation on agar plates. The discriminatory power of IS1301 fingerprinting exceeded that of typing by serogrouping and antigen sequencing of the outer membrane proteins PorA and FetA, as determined by the analysis of 52 epidemiologically unrelated strains. In addition, the method provided conclusive results with regard to the comparison of strains from clusters of IMD. The investigation of insertion sites of IS1301 revealed several new intragenic insertions, among others, into open reading frames homologous to mafB and tspB. A previously described insertion in nadA was present in more than two-thirds of the strains analyzed, suggesting that NadA is probably an unreliable vaccine candidate for the prevention of ET-15 disease.

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.

Invasive meningococcal disease in Quebec, Canada, due to an emerging clone of ST-269 serogroup B meningococci with serotype antigen 17 and serosubtype antigen P1.19 (B:17:P1.19)

During periods of endemic meningococcal disease, serogroup B Neisseria meningitidis is responsible for a significant percentage of invasive diseases, and no particular clone or strain predominates (F. E. Ashton and D. A. Caugant, Can. J. Microbiol. 47: 293-289, 2001), However, in the winter of 2004 to 2005, a cluster of serogroup B meningococcal disease occurred in one region in the province of Québec, Canada. The N. meningitidis strain responsible for this cluster of cases was identified as sequence type ST-269 with the antigenic formula B:17:P1.19. Retrospective analysis of isolates from 2000 onwards showed that this clone first emerged in the province of Québec in 2003. The emergence of this clone of serogroup B meningococci occurred after a mass vaccination against serogroup C N. meningitidis, suggesting possible capsule replacement.

Conjugate vaccines for preventing meningococcal C meningitis and septicaemia

BACKGROUND

Meningococcal polysaccharide (MPLS) vaccines protect against Serogroup C disease, but do not produce an immune response in infants less than two years of age. This limitation can be overcome by linking C polysaccharide to carrier proteins ('conjugating'), to create meningococcal serogroup C conjugate (MCC) vaccines. In the absence of trial data, the immune response to vaccination has been considered to be a reasonable surrogate for vaccine protection.

OBJECTIVES

To assess the immunogenicity, safety and efficacy of MCC vaccines for preventing meningitis and septicaemia.

SEARCH STRATEGY

We searched the Cochrane Central Register Controlled Trials (CENTRAL) (The Cochrane Library Issue 3, 2005); MEDLINE (1966 to September, Week 1 2005); and EMBASE (1990 to June 2005) and references of studies.

SELECTION CRITERIA

Randomised controlled trials (RCTs) and controlled clinical trials (CCTs) in humans comparing MCC vaccines against a control vaccine or none. In the absence of any trials on vaccine efficacy, population-based observational studies about effectiveness were included.

DATA COLLECTION AND ANALYSIS

Two authors independently screened the results of the literature searches, selected eligible studies, extracted the data and evaluated the quality of them.

MAIN RESULTS

The studies showed that MCC vaccine was highly immunogenic in infants after two and three doses, in toddlers after one and two doses and in older age groups after one dose. In general higher titres were generated after MCC than after MPLS vaccines. Immunological hypo-responsiveness seen after repeated doses of MPLS vaccine may be overcome with MCC. Observational studies have documented a significant decline in meningococcal C disease in countries where MCC vaccines have been widely used. The timing of the vaccinations schedules, the specific conjugate used, and the vaccines given concomitantly or combined, may be important.

AUTHORS' CONCLUSIONS

The MCC vaccine appears to be safe, immunogenic and able to induce immunological memory in all age groups. Observational studies strongly suggest that MCC is clinically effective.

Invasive meningococcal disease in children in Greece: comparison of serogroup A disease with disease caused by other serogroups

Although invasive meningococcal disease caused by serogroup A is not prevalent in developed countries, a considerable number of cases were recently recorded in Greece. In this study, serogroup A meningococcal disease was compared prospectively with meningococcal disease caused by other serogroups, using similar settings of testing and management during a 5-year period between 1999 and 2003. The Neisseria meningitidis serogroup was determined in 262 cases. Serogroup B predominated, accounting for 158 (60%) of the cases. Serogroup A was second most frequent (19%), followed by serogroups W135 (11%), C (8%), and Y (2%). No cases due to serogroup C were recorded during the last year of the study. Patients with serogroup A disease were older and had a milder course compared to patients infected with serogroups B or C. Toxic appearance, purpura, thrombocytopenia, abnormal coagulation tests, and the need for admission to the intensive care unit, fluid resuscitation, inotropic drugs, and mechanical ventilation were less common. Although morbidity and mortality were lower in these patients, the differences were not significant. Serogroup B is predominant in our area, and the introduction of an effective vaccine against it is a priority. Serogroup A has emerged as the second most common serogroup, but the illness associated with it is milder.

Phenotypic assessment of Neisseria meningitidis isolates obtained from patients with invasive meningococcal disease in Greece, 1993–2003: Implications for serogroup B vaccines based on PorA serosubtype antigens

Serogroup B is the major isolate from patients with invasive meningococcal disease (IMD) in Greece. This study used the whole cell enzyme-linked immuosorbent assay (ELISA) with monoclonal antibodies to screen Neisseria meningitidis isolates obtained from patients with IMD between 1993 and 2003 to determine if serosubtypes included in the hexavalent Por A OMP vaccines being tested in northern Europe were prevalent in Greece. During this period there were significant changes in the proportions of serogroups B and C isolated from patients. Serogroup C was predominant in 1996-1997 but fell sharply with corresponding increases in serogroup B. Of the 591 isolates sent to the National Meningitis Reference Laboratory in Athens during this period, 325 (55%) were serogroup B. Among those tested for serosubtype, porA proteins used for the vaccine being tested in Britain were detected on 85/284 (30%) strains and for the vaccine being tested in the Netherlands 175/284 (62%). P1.14 (58/284, 20%) the predominant serosubtype among the Greek isolates, is not present in either vaccine formulation; 23/284 (8%) strains did not react with any of the monoclonal antibodies. Our results indicate that introduction of the vaccines currently being evaluated in northern Europe would not be warranted in the Greek population.

Are antibodies to the capsular polysaccharide of Neisseria meningitidis group B and Escherichia coli K1 associated with immunopathology?

As polysialic acid (PSA), the capsule of Group B meningococcus (GBM) and Escherichia coli K1, is a component of mammalian glycopeptides, there is concern that vaccines against PSA could induce immunopathology. Purified PSA is not immunogenic; however, as a component of bacteria or bound to proteins, it induces protective antibodies. In this review, we did not unearth data indicating an association of IgG anti-PSA with immunopathology in experimental animals or humans. We found no increased incidence of autoimmunity from GBM infections in our review of the natural history/sequellae of Neisseria meningitis infections. Accordingly, we propose that clinical trials of PSA conjugate vaccines, be considered.

Cost-effectiveness of conjugate meningococcal vaccination strategies in the United States

CONTEXT

The US Food and Drug Administration approved a meningococcal conjugate A/C/Y/W-135 vaccine (MCV-4) for use in persons aged 11 to 55 years in January, 2005; licensure for use in younger age groups is expected in 2 to 4 years.

OBJECTIVE

To evaluate and compare the projected health and economic impact of MCV-4 vaccination of US adolescents, toddlers, and infants.

DESIGN

Cost-effectiveness analysis from a societal perspective based on data from Active Bacterial Core Surveillance (ABCs) and other published and unpublished sources. Sensitivity analyses in which key input measures were varied over plausible ranges were performed.

SETTING AND PATIENTS

A hypothetical 2003 US population cohort of children 11 years of age and a 2003 US birth cohort.

INTERVENTIONS

Hypothetical routine vaccination of adolescents (1 dose at 11 years of age), toddlers (1 dose at 1 year of age), and infants (3 doses at 2, 4, and 6 months of age). Each vaccination scenario was compared with a "no-vaccination" scenario.

MAIN OUTCOME MEASURES

Meningococcal cases and deaths prevented, cost per case prevented, cost per life-year saved, and cost per quality-adjusted life-year saved.

RESULTS

Routine MCV-4 vaccination of US adolescents (11 years of age) would prevent 270 meningococcal cases and 36 deaths in the vaccinated cohort over 22 years, a decrease of 46% in the expected burden of disease. Before program costs are counted, adolescent vaccination would reduce direct disease costs by $18 million and decrease productivity losses by $50 million. At a cost per vaccination (average public-private price per dose plus administration fees) of $82.50, adolescent vaccination would cost society $633000 per meningococcal case prevented and $121000 per life-year saved. Key variables influencing results were disease incidence, case-fatality ratio, and cost per vaccination. The cost-effectiveness of toddler vaccination is essentially equivalent to adolescent vaccination, whereas infant vaccination would be much less cost-effective.

CONCLUSIONS

Routine MCV-4 vaccination of US children would reduce the burden of disease in vaccinated cohorts but at a relatively high net societal cost. The projected cost-effectiveness of adolescent vaccination approaches that of recently adopted childhood vaccines under conditions of above-average meningococcal disease incidence or at a lower cost per vaccination.

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.

The case-fatality rate of meningococcal disease in Catalonia, 1990-1997

The objective was to analyse the case-fatality rate (CFR) of meningococcal disease (MD) in Catalonia, Spain. A retrospective study was carried out. Clinical histories of cases of MD reported for the period 1990-1997 in Catalonia were reviewed. For all cases, the variables gender, age, clinical type, y of presentation, province, phenotype and death by meningococcal disease were collected. The association between death and the other variables was studied by bivariate and unconditional logistic regression analysis. In the 2343 cases studied there were 146 deaths (6.2%) due to meningococcal disease. The CFR was higher in females (OR: 1.5, 95%CI: 1.1-2.1), in the 20 to 49 y (OR: 2.4, 95%CI: 1.2-4.9) and > or = 50 y (OR: 5.3, 95%CI: 2.8-10.1) age groups, in cases with septicaemia (OR: 2.4, 95%CI: 1.6-3.5), in the cases produced by serogroup A (OR: 4.7, 95%CI: 1.0-23.4) and in cases occurring during 1993 (OR: 2.1, 95%CI: 1.1-4.1) or in the province of Lleida (OR: 2.9, 95%CI: 1.2-7.2). In the multivariate analysis, death was associated with the 20-49 y age group (OR: 3.9, 95%CI: 1.8-8.4), the > or = 50 y age group (OR: 7.3, 95%CI: 3.6-14.7), septicaemia (OR: 3.1; 95%CI: 2.0-4.7) and residing in the province of Lleida (OR: 3.2; 95%CI: 1.2-8.5). The CFR of meningococcal disease in Catalonia was not associated with the emergent phenotype C:2b:P1.2,5 strain, which caused an outbreak in other regions of Spain.

The impact of meningococcal serogroup C conjugate vaccine in Scotland

The increasing number of cases of serogroup C meningococcal disease in Scotland in the late 1990s coincided with the availability of a new meningococcal conjugate serogroup C (MCC) vaccine that, from 1999 onwards, was offered to all individuals aged <20 years. Annual incidence rates between 1994 and 2003 were calculated in 3 age groups (<5 years old; 5-19 years old; and >or=20 years old), and Poisson regression models were used to verify disease trends over time. Dramatic reductions (P<.05) in the incidence of serogroup C meningococcal disease were seen in target age groups: from 15.8 incidents per 100,000 subjects in 1999 (95% confidence interval [CI], 11.3-20.3) to 0.7 incidents per 100,000 subjects in 2001 (95% CI, -0.3 to 1.6), for subjects <5 years old, and from 6.7 incidents per 100,000 subjects in 1999 (95% CI, 5.1-8.3) to 1.5 incidents per 100,000 subjects in 2001 (95% CI, 0.7-2.3), for subjects 5-19 years old. An increasing incidence of serogroup B meningococcal disease in individuals 5-19 years old was clearly established before the campaign began. A 30% decrease in the case-fatality rate for individuals <20 years old was not significant (P=.1598). The MCC vaccine program has been highly effective in Scotland, leading to substantial reductions in serogroup C meningococcal disease and meningococcal mortality, with no adverse effects on other groups.

Epidemiology of meningococcal disease in Switzerland, 1999-2002

In Switzerland, immunisation against serogroup C meningococcal disease is recommended for persons at increased risk but is not included in the national vaccination programme. The aim of this study was to present the nationwide surveillance data on invasive meningococcal disease collected from 1999 to 2002, emphasising the evolution in the absence of extended vaccination. The number of reported cases of meningococcal disease peaked at 178 cases in 2000 (incidence rate of 2.5/100,000 person-years), with 61% of all cases attributed to serogroup C meningococci (incidence rate, 1.5/100,000 person-years). Since 2001, a spontaneous decrease in the reported cases was observed, resulting in an overall incidence rate of 1.4/100,000 person-years in 2002 (serogroup C cases, 0.8/100,000 person-years). On the other hand, the case-fatality rate of serogroup C cases increased to 18% in 2002, leading to an increase in the overall case-fatality rate from 8% to 14% (P>0.05). The small sample size reduces the interpretability of this observation. However, when the introduction of a generalised vaccination against serogroup C meningococcal disease is discussed, the fluctuations in the number of vaccine-preventable deaths should receive greater attention.

Hospitalisations for gastroenteritis: the role of rotavirus

To determine the proportion of hospitalisations for gastroenteritis caused by rotavirus, we tested for rotavirus stool samples of all children under the age of five hospitalised for gastroenteritis between 1 December 1999 and 30 May 2000 in seven community and specialised hospitals in Quebec. Of 944 children hospitalised, 565 (59.9%) were screened for rotavirus and 405 (71.7%) tested positive. From December to April, the proportion of positive results rose from 51.6 to 78.1%. Compared with children whose test results were negative, children who tested positive presented vomiting more frequently upon admission (88.9 versus 60.4%) and needed IV fluids in greater proportion (94.1 versus 78.0%), but spent less time in hospital (2.8 versus 3.3 days). Aside from dehydration, no complications were noted. In Quebec, a large majority of winter and spring hospitalisations for gastroenteritis in children is attributable to rotavirus.

Protective activity of group C anticapsular antibodies elicited in two-year-olds by an investigational quadrivalent Neisseria meningitidis-diphtheria toxoid conjugate vaccine

BACKGROUND

Quadrivalent capsular group A, C, Y and W-135 meningococcal conjugate (MC-4) vaccines are under development

OBJECTIVE

Predict efficacy of an investigational MC-4 vaccine in 2-year-old children for prevention of group C disease.

DESIGN

Measurement of group C antibody concentrations, avidity and bactericidal and passive protective activity in sera from 2-year-olds given 1 dose of MC-4 vaccine (N = 30) and 3-year-olds (N = 30) and adults (N = 26) given 1 dose of meningococcal polysaccharide (MPS-4) vaccine.

RESULTS

One month after vaccination, the geometric mean anticapsular antibody concentration of children given MC-4 vaccine (3.1 microg/ml) was lower than that of control children (5.1 microg/ml; P < 0.04) or adults immunized with MPS-4 vaccine (22.9 microg/ml; P < 0.001). However, the percent of sera with protective bactericidal titers of >/=1/4 was higher in children given MC-4 vaccine (50%, versus 17% in children given MPS-4 vaccine; P < 0.02) and was not significantly different from that of immunized adults (65%). In children, the mean antibody avidity at 1 month was higher in the MC-4 group (22 nM versus 16 nM in the MPS-4 group; P = 0.002), and at 6 months increased in the MC-4 group (28 nM; P < 0.001), but not in the MPS-4 vaccine group (17 nM). Higher avidity antibody gave greater passive protection in the infant rat bacteremia model than did lower avidity antibody (P < 0.03).

CONCLUSIONS

Although MPS-4 vaccine elicited higher group C serum antibody concentrations in 3-year-olds than did MC-4 vaccine in 2-year-olds, the higher antibody avidity after MC-4 vaccine resulted in higher bactericidal and passive protective activity.

The societal value of universal childhood vaccination

Availability of new vaccines preventing infectious diseases in healthy children populations is increasing worldwide. In Canada, despite the current recommendation of the National Advisory Committee on Immunization to include recent vaccines in routine schedule, only a few provinces have incorporated some of the newer vaccines in routine vaccination programs. A review was undertaken of economic evaluations of childhood vaccination strategies performed from the societal point of view in industrialized countries, to gain perspective on their global benefits. The general trend supports most universal vaccination programs as cost-saving or cost-effective for society. Comparison of vaccination programs with other health care interventions indicates that vaccines are often one of society's best healthcare investments. Current data suggest that the Canadian society would benefit from a more complete immunization program.

Cost-effectiveness of immunization strategies for the control of serogroup C meningococcal disease

This study compares the cost-effectiveness of a control strategy for serogroup C meningococcal disease (CMD) relying on surveillance and implementation of a mass immunization campaign effective 1 year after the beginning of an epidemic with strategies based on routine immunization, using either three doses of serogroup C conjugate vaccine given in early infancy or one dose at 1 year of age. The simulation model is based on 25 birth cohorts followed up to age 24 years, and seven epidemiological scenarios including low and high level endemicity, and one to five epidemics over a 49-year period. Epidemiological and cost data were mainly collected in the province of Quebec, Canada. Results indicate that the most effective strategy is a three-dose routine program, with the least effective strategy being mass immunization. A one-dose routine program is the most cost-effective strategy in most likely scenarios. In a societal perspective with a vaccine purchase price of CDN$ 50 per dose, the average incremental cost of the one-dose strategy would be $ 190,000 per case averted, US$ 23,000 per life-year gained, and US$ 42,000 per QALY gained. If vaccine-induced immunity is waning rapidly, mass immunization or routine vaccination with booster dose(s) would be the best control options.

Phenotypic and genetic characterization of a unique variant of serogroup C ET-15 meningococci (with the antigenic formula C:2a:P1.7,1) causing invasive meningococcal disease in Quebec, Canada

Serogroup C Neisseria meningitidis belonging to the electrophoretic type (ET) ET-15, a variant of ET-37, is endemic in Canada. Like other serogroup C ET-37 meningococci, the endemic ET-15 strains are usually found to carry the serotype and serosubtype antigens of 2a:P1.5,2. In 2001, a sudden increase in the number of cases of serogroup C meningococcal disease in Quebec, Canada, was caused by an antigenic variant of the ET-15 strain. This antigenic variant carries the unique serosubtype marker of P1.7,1. Strains of C:2a:P1.7,1 meningococci were not isolated in Canada in large numbers prior to 2001, and the characteristics of these meningococcal strains linked to an outbreak in Quebec, Canada, are described in the present study.

Risk and prevention of meningococcal disease among education workers: A review

The aims of the present study were to review the risk of invasive meningococcal disease (IMD) among education workers, particularly pregnant women, and to evaluate preventive measures, in a context of endemicity, outbreak or epidemic as observed in the province of Quebec. The literature was reviewed and persons in charge of IMD surveillance in France, Quebec, the United Kingdom and the United States were interviewed. Surveys of asymptomatic carriage of Neisseria meningitidis show that transmission among students is higher than transmission between students and teachers. IMD incidence among education workers was analyzed in Cheshire (United Kingdom) in the period from 1997 to 1999, and the results indicated a risk six times higher than that in the general population. Overestimation of the magnitude of the risk is possible because the analysis focused on a cluster. None of the population-based studies of IMD mentioned a risk of secondary cases among education workers. Six IMD cases in education workers were identified in five clusters in schools in the United Kingdom, but not in the other countries. There is no epidemiological study on IMD risk among pregnant women, and this factor was not mentioned in any published review of IMD. Immunization of education workers at the beginning of their employment, using serogroup C glycoconjugate vaccine or a combined A, C, W-135, and Y conjugate vaccine (still under development), could reduce IMD risk, but the cost effectiveness of this measure should be evaluated. The societal benefit of excluding pregnant women from the work place during an outbreak seems to be very low, even if disease risk could be decreased for this specific group. When chemoprophylaxis is indicated for the control of an outbreak in an educational setting, treatment should be offered both to students and teachers in the group at risk.

Should university students be vaccinated against meningococcal disease in Canada?

OBJECTIVE

To evaluate the benefit and costs of vaccination of university students against invasive meningococcal disease (IMD) in Canada.

METHODS

Published studies were reviewed and a simulation model was used.

RESULTS

IMD risk seems to be of low magnitude, but consequences can be dramatic. Over a 10-year period, IMD risk reduction would be slightly greater using a monovalent C conjugate vaccine than a quadrivalent polysaccharide vaccine. From a societal perspective, costs per quality-adjusted life-years gained would be between $135,000 and $698,000, according to epidemiological scenarios and with vaccine purchase prices between $35 and $50 per dose.

CONCLUSIONS

Economic indices exceed proposed criteria for cost effective public health programs, but from the perspective of students and parents, the cost of vaccination might be worth the benefit.

[Public health: the control of meningococcal disease in Quebec]

A first outbreak of serogroup C meningococcal disease occurred in the province of Quebec in 1990-1992 and lead to a mass immunization campaign using polysaccharide vaccines. In 2001, a second outbreak was identified and a mass vaccination campaign was carried out, using the newly licensed conjugate vaccine. Clinical, epidemiological, economic and social studies were instrumental in the decision making for implementing these control programs.

Reprogramming the host response in bacterial meningitis: how best to improve outcome?

Despite effective antibiotic therapy, bacterial meningitis is still associated with high morbidity and mortality in both children and adults. Animal studies have shown that the host inflammatory response induced by bacterial products in the subarachnoid space is associated with central nervous system injury. Thus, attenuation of inflammation early in the disease process might improve the outcome. The feasibility of such an approach is demonstrated by the reduction in neurologic sequelae achieved with adjuvant dexamethasone therapy. Increased understanding of the pathways of inflammation and neuronal damage has suggested rational new targets to modulate the host response in bacterial meningitis, but prediction of which agents would be optimal has been difficult. This review compares the future promise of benefit from the use of diverse adjuvant agents. It appears unlikely that inhibition of a single proinflammatory mediator will prove useful in clinical practice, but several avenues to reprogram a wider array of mediators simultaneously are encouraging. Particularly promising are efforts to adjust combinations of cytokines, to inhibit neuronal apoptosis and to enhance brain repair.

Cost-benefit model comparing two alternative immunisation programmes against serogroup C meningococcal disease: for Quebec residents aged 2 months to 20 years

OBJECTIVE

To evaluate the most efficient approach to managing an outbreak of serogroup C meningococcal disease. An early planned mass immunisation programme (MIP) was compared with a delayed programme implemented at the peak of a meningococcal outbreak.

DESIGN AND SETTING

A cost-benefit model was constructed of meningococcal cases reported in Quebec, Canada, from 1990-1993, before and after the MIP, during the winter of 1992-1993, when 84% of residents aged 6 months to 20 years were vaccinated. Epidemiological data from 1990-1993 were transposed to 2002-2003 under the assumption that Quebec is on the brink of an identical outbreak cycle. All Quebec residents aged 2 months to 20 years were assumed to be vaccinated, which required a total of 1.7 million doses of conjugated vaccine. Clinical and economic outcomes of both vaccination scenarios were compared. All costs were transformed to 2001 Canadian dollars ($Can), at an annual inflation rate of 3%. Future earnings due to premature death were discounted at 5% per year with a 3% increase in wages per year and a 9% unemployment rate.

PERSPECTIVE

Ministry of Health and society.

MAIN OUTCOME MEASURES

The number of new cases avoided and the prevention of hospital and societal costs due to meningococcal disease-attributed premature mortality and morbidity, and direct costs associated with implementation of a MIP.

RESULTS

When compared with a delayed MIP over a 14-month period, an early planned MIP would have prevented 112 new cases of meningococcal disease (16 deaths, 21 major complications) while saving $ Can 37.1 million in total direct costs to the Ministry of Health and an additional $ Can 17.4 million in societal costs in the province of Quebec.

CONCLUSION

An early planned MIP implemented in Quebec in September 2001, should be cost beneficial compared with delaying mass immunisation until a meningococcal outbreak is underway. Although this conclusion is limited by the assumption that epidemiological trends in 2001 in absence of a MIP would have been similar to that observed in the early 1990s prior to the MIP, the analysis still indicates that an early MIP in the 1990s would have been cost beneficial compared with a delayed MIP.