The impact of the meningococcal serogroup C conjugate vaccine in Canada between 2002 and 2012

Meningococcal disease in North America: Updates from the Global Meningococcal Initiative

This review summarizes the recent Global Meningococcal Initiative (GMI) regional meeting, which explored meningococcal disease in North America. Invasive meningococcal disease (IMD) cases are documented through both passive and active surveillance networks. IMD appears to be decreasing in many areas, such as the Dominican Republic (2016: 18 cases; 2021: 2 cases) and Panama (2008: 1 case/100,000; 2021: <0.1 cases/100,000); however, there is notable regional and temporal variation. Outbreaks persist in at-risk subpopulations, such as people experiencing homelessness in the US and migrants in Mexico. The recent emergence of β-lactamase-positive and ciprofloxacin-resistant meningococci in the US is a major concern. While vaccination practices vary across North America, vaccine uptake remains relatively high. Monovalent and multivalent conjugate vaccines (which many countries in North America primarily use) can provide herd protection. However, there is no evidence that group B vaccines reduce meningococcal carriage. The coronavirus pandemic illustrates that following public health crises, enhanced surveillance of disease epidemiology and catch-up vaccine schedules is key. Whole genome sequencing is a key epidemiological tool for identifying IMD strain emergence and the evaluation of vaccine strain coverage. The Global Roadmap on Defeating Meningitis by 2030 remains a focus of the GMI.

Favorable prognosis of vaccine-associated immune thrombocytopenia in children is correlated with young age at vaccination: Retrospective survey of a nationwide disease registry

Childhood vaccine-associated immune thrombocytopenia (ITP) has a mostly favorable prognosis. To identify factors associated with prognosis, a retrospective survey was conducted with children with ITP who were registered in the Japanese Society of Pediatric Hematology/Oncology registry from 2008 to 2011. A total of 477 patients were categorized into four groups by event preceding ITP onset: vaccine-precedence (VP; n = 43), vaccine/infection-precedence (VIP; n = 34), infection-precedence (IP; n = 162), and no vaccine/infection-precedence (NVI; n = 238). Compared to IP and NVI, VP and VIP were significantly younger at diagnosis, with the age distribution peaking at infancy, and more frequently had favorable prognosis. Time to platelet recovery to 100 × 10³/µL was significantly faster for VP and VIP than NVI. Multivariate Cox regression analysis with sex, age at diagnosis, infection-precedence, and vaccine-precedence as variables revealed age < 36 months (HR 0.992, 95% CI 0.989-0.995; p < 0.001) and male sex (HR 0.770, 95% CI 0.623-0.952; p = 0.015) as associated factors, but not infection-precedence (p = 0.149) or vaccine-precedence (p = 0.650). In subgroup analysis in patients < 36 months, age at diagnosis (p < 0.001) was the only associated factor. Favorable prognosis of childhood vaccine-associated ITP is correlated with young age at vaccination, but not with vaccination itself.

Meningococcal disease epidemiology in Brazil (2005-2018) and impact of MenC vaccination

BACKGROUND

Meningococcal disease (MD) presents a substantial public health problem in Brazil. Meningococcal C conjugate (MenC) vaccination was introduced into the routine infant immunization program in 2010, followed by adolescent vaccination in 2017. We evaluated changes in national and regional MD incidence and mortality between 2005 and 2018, serogroup distribution and vaccine coverage.

METHODS

Data were obtained from national surveillance systems from 2005 to 2018. Age-stratified incidence and mortality rates were calculated and a descriptive time-series analysis was performed comparing rates in the pre-(2005-2009) and post-vaccination (2011-2018) periods; MD due to specific meningococcal serogroups were analyzed in the pre-(2007-2009) and post-vaccination (2011-2018) periods.

RESULTS

From 2005 to 2018, 31,108 MD cases were reported with 6496 deaths; 35% of cases and deaths occurred in children < 5 years. Incidence and mortality rates declined steadily since 2012 in all age-strata, with significantly lower incidence and mortality in the post-vaccine introduction period in children aged < 1-year, 1-4 years, 5-9 years and 10-14 years. A significant decline in MenC disease in children < 5 years was observed following MenC vaccine introduction; infants < 1 year, from 3.30/100,000 (2007-2009) to 1.08/100,000 (2011-2018) and from 1.44/100,000 to 0.42/100,000 in 1-4-year-olds for these periods. Reductions in MenB disease was also observed. MenW remains an important cause of MD with 748 cases reported across 2005-2018. While initial infant vaccination coverage was high (>95% nationwide), this has since declined (to 83% in 2018); adolescent uptake was < 20% in 2017/18). Regional variations in outcomes and vaccine coverage were observed.

CONCLUSION

A substantial decline in incidence and mortality rates due to MD was seen following MenC vaccine introduction in Brazil, especially among children < 5 years chiefly driven by reductions in MenC serogroup. While these benefits are considerable, the prevalence of MD due to other serogroups such as MenW and MenB remains a concern. A video summary linked to this article can be found on Figshare: https://doi.org/10.6084/m9.figshare.13379612.v1.

Systematic literature review of the impact and effectiveness of monovalent meningococcal C conjugated vaccines when used in routine immunization programs

BACKGROUND

Monovalent meningococcal C conjugate vaccine (MCCV) was introduced into the routine immunization program in many countries in Europe and worldwide following the emergence of meningococcal serogroup C (MenC) in the late 1990s. This systematic literature review summarizes the immediate and long-term impact and effectiveness of the different MCCV vaccination schedules and strategies employed.

METHODS

We conducted a systematic literature search for peer-reviewed, scientific publications in the databases of MEDLINE (via PubMed), LILACS, and SCIELO. We included studies from countries where MCCV have been introduced in routine vaccination programs and studies providing the impact and effectiveness of MCCV published between 1st January 2001 and 31st October 2017.

RESULTS

Forty studies were included in the review; 30 studies reporting impact and 17 reporting effectiveness covering 9 countries (UK, Spain, Italy, Canada, Brazil, Australia, Belgium, Germany and the Netherlands). Following MCCV introduction, significant and immediate reduction of MenC incidence was consistently observed in vaccine eligible ages in all countries with high vaccine uptake. The reduction in non-vaccine eligible ages (especially population > 65 years) through herd protection was generally observed 3-4 years following introduction. Vaccine effectiveness (VE) was mostly assessed through screening methods and ranged from 38 to 100%. The VE was generally highest during the first year after vaccination and waned over time. The VE was better maintained in countries employing catch-up campaigns in older children and adolescents, compared to routine infant only schedules.

CONCLUSIONS

MCCV were highly effective, showing a substantial and sustained decrease in MenC invasive meningococcal disease. The epidemiology of meningococcal disease is in constant transition, and some vaccination programs now include adolescents and higher valent vaccines due to the recent increase in cases caused by serogroups not covered by MCCV. Continuous monitoring of meningococcal disease is essential to understand disease evolution in the setting of different vaccination programs.

Herd Protection against Meningococcal Disease through Vaccination

Reduction in the transmission of Neisseria meningitidis within a population results in fewer invasive disease cases. Vaccination with meningococcal vaccines composed of high weight capsular polysaccharide without carrier proteins has minimal effect against carriage or the acquisition of carriage. Conjugate vaccines, however, elicit an enhanced immune response which serves to reduce carriage acquisition and hinder onwards transmission. Since the 1990s, several meningococcal conjugate vaccines have been developed and, when used in age groups associated with higher carriage, they have been shown to provide indirect protection to unvaccinated cohorts. This herd protective effect is important in enhancing the efficiency and impact of vaccination. Studies are ongoing to assess the effect of protein-based group B vaccines on carriage; however, current data cast doubt on their ability to reduce transmission.

Vaccines against Meningococcal Diseases

Neisseria meningitidis is the main cause of meningitis and sepsis, potentially life-threatening conditions. Thanks to advancements in vaccine development, vaccines are now available for five out of six meningococcal disease-causing serogroups (A, B, C, W, and Y). Vaccination programs with monovalent meningococcal serogroup C (MenC) conjugate vaccines in Europe have successfully decreased MenC disease and carriage. The use of a monovalent MenA conjugate vaccine in the African meningitis belt has led to a near elimination of MenA disease. Due to the emergence of non-vaccine serogroups, recommendations have gradually shifted, in many countries, from monovalent conjugate vaccines to quadrivalent MenACWY conjugate vaccines to provide broader protection. Recent real-world effectiveness of broad-coverage, protein-based MenB vaccines has been reassuring. Vaccines are also used to control meningococcal outbreaks. Despite major improvements, meningococcal disease remains a global public health concern. Further research into changing epidemiology is needed. Ongoing efforts are being made to develop next-generation, pentavalent vaccines including a MenACWYX conjugate vaccine and a MenACWY conjugate vaccine combined with MenB, which are expected to contribute to the global control of meningitis.

Paediatric Investigators Collaborative Network on Infections in Canada (PICNIC) study of the current landscape of invasive meningococcal disease in children

Background

Immunizations have led to a decrease in the incidence of invasive meningococcal disease (IMD) in Canada, but this infection still leads to significant morbidity and mortality.

Objectives

The purpose of this study was to determine the burden of illness and management of IMD in paediatric hospitals.

Methods

Data were collected on all cases of IMD in eight paediatric hospitals from 2013 to 2017.

Results

There were 17 cases of IMD. Three of eight hospitals had no cases. Just over half of the cases were serogroup B (n=9); a quarter (n=4) were serogroup W; less than a quarter (n=3) were serogroup Y; and one was unknown. Two infected children were not started on antibiotics until day one and day five after the initial blood culture was collected, but had uneventful recoveries. Six cases required admission to intensive care units; two died. Six cases had probable or proven meningitis. Thrombocytopenia was documented in seven cases. All cases had elevated C-reactive protein levels. Seven children received more than seven days of antibiotics; of these seven, only two had complications that justified prolonged therapy (subdural empyema and septic knee). Six cases had a central line placed.

Conclusion

IMD is now rare in Canadian children, but about one-third of the cases in our study required treatment in the intensive care unit and two died. Clinicians appear to not always be aware that a five to seven-day course is adequate for uncomplicated cases of bacteremia or meningitis.

Active surveillance of acute paediatric hospitalisations demonstrates the impact of vaccination programmes and informs vaccine policy in Canada and Australia

Sentinel surveillance of acute hospitalisations in response to infectious disease emergencies such as the 2009 influenza A(H1N1)pdm09 pandemic is well described, but recognition of its potential to supplement routine public health surveillance and provide scalability for emergency responses has been limited. We summarise the achievements of two national paediatric hospital surveillance networks relevant to vaccine programmes and emerging infectious diseases in Canada (Canadian Immunization Monitoring Program Active; IMPACT from 1991) and Australia (Paediatric Active Enhanced Disease Surveillance; PAEDS from 2007) and discuss opportunities and challenges in applying their model to other contexts. Both networks were established to enhance capacity to measure vaccine preventable disease burden, vaccine programme impact, and safety, with their scope occasionally being increased with emerging infectious diseases’ surveillance. Their active surveillance has increased data accuracy and utility for syndromic conditions (e.g. encephalitis), pathogen-specific diseases (e.g. pertussis, rotavirus, influenza), and adverse events following immunisation (e.g. febrile seizure), enabled correlation of biological specimens with clinical context and supported responses to emerging infections (e.g. pandemic influenza, parechovirus, COVID-19). The demonstrated long-term value of continuous, rather than incident-related, operation of these networks in strengthening routine surveillance, bridging research gaps, and providing scalable public health response, supports their applicability to other countries.

The everchanging epidemiology of meningococcal disease worldwide and the potential for prevention through vaccination

Neisseria meningitidis is a major cause of bacterial meningitis and septicaemia worldwide and is associated with high case fatality rates and serious life-long complications among survivors. Twelve serogroups are recognised, of which six (A, B, C, W, X and Y) are responsible for nearly all cases of invasive meningococcal disease (IMD). The incidence of IMD and responsible serogroups vary widely both geographically and over time. For the first time, effective vaccines against all these serogroups are available or nearing licensure. Over the past two decades, IMD incidence has been declining across most parts of the world through a combination of successful meningococcal immunisation programmes and secular trends. The introduction of meningococcal C conjugate vaccines in the early 2000s was associated with rapid declines in meningococcal C disease, whilst implementation of a meningococcal A conjugate vaccine across the African meningitis belt led to near-elimination of meningococcal A disease. Consequently, other serogroups have become more important causes of IMD. In particular, the emergence of a hypervirulent meningococcal group W clone has led many countries to shift from monovalent meningococcal C to quadrivalent ACWY conjugate vaccines in their national immunisation programmes. Additionally, the recent licensure of two protein-based, broad-spectrum meningococcal B vaccines finally provides protection against the most common group responsible for childhood IMD across Europe and Australia. This review describes global IMD epidemiology across each continent and trends over time, the serogroups responsible for IMD, the impact of meningococcal immunisation programmes and future needs to eliminate this devastating disease.

Persistence of bactericidal antibodies following primary and booster MenACWY-TT vaccination of toddlers: A review of clinical studies

The long-term persistence of antibody responses following primary vaccination with quadrivalent conjugate vaccines targeting meningococcal serogroups A, C, W, and Y (MenACWY) and the duration of protection following a booster dose have not been fully elucidated, particularly in children who received primary dosing as toddlers. This review summarizes the findings of one phase 3 and three phase 2 open-label, randomized clinical studies that assessed the long-term antibody persistence of MenACWY conjugated to tetanus toxoid as a carrier protein (MenACWY-TT) in toddlers. Following primary vaccination, antibody responses persisted for approximately 2-3 years and then decreased up to 5 years after vaccination. Geometric mean titers remained elevated for all serogroups up to 5 years after primary vaccination. In children who received a booster dose of MenACWY-TT at 4-5 years after primary dosing as toddlers, antibody responses were documented in >99% of subjects across all serogroups, with minimal decreases in antibody persistence from 2-6 years after booster vaccination. The persistence of meningococcal serogroup C (MenC) antibody responses was similar between MenACWY-TT and MenC vaccine recipients after primary and booster dosing. Together, these findings indicate that antibody responses to primary MenACWY-TT vaccination persist for 2-3 years. Additionally, these findings indicate that in subjects who receive primary MenACWY-TT vaccination as toddlers, the antibody response to booster MenACWY-TT vaccination lasts for up to 6 years and suggest that immune memory is afforded at least into early adolescence, which is an age group at increased risk of invasive meningococcal disease.

Estimated susceptibility of Canadian meningococcal B isolates to a meningococcal serogroup B vaccine (MenB-FHbp)

BACKGROUND

Invasive meningococcal disease caused by Neisseria meningitidis serogroup B (MenB) remains a health risk in Canada and globally. Two MenB vaccines are now approved for use. An understanding of the genotype of Canadian strains and the potential strain coverage conferred by the MenB-FHbp vaccine is needed to inform immunization policies.

METHODS

Serogroup B Neisseria meningitidis strains responsible for meningococcal disease in Canada from 2006 to 2012 were collected as part of the Canadian Immunization Monitoring Program Active surveillance network. Genotypic analysis was done on MenB isolates from 2006 to 2012 with determination of fHbp surface expression for a subset of isolates: those occurring from 2010 to 2012.

RESULTS

Two clonal complexes (cc269 and cc41/44) were observed in 68.8% of the 276 isolates. A total of 50 different fHbp peptides were identified among isolates from 2006 to 2012. Surface expression of fHbp was detected on 95% of MenB isolates from 2010 to 2012 and 91% of isolates expressed fHbp at levels that are predicted to be susceptible to the bactericidal immune response elicited by the MenB-FHbp vaccine. Some regional differences were observed, particularly in isolates from British Columbia and Quebec.

CONCLUSION

The majority of MenB isolates responsible for meningococcal disease in Canada expressed fHbp at levels predicted to be sufficient for complement mediated bactericidal activity in the presence of MenB-FHbp induced serum antibodies.

Epidemiology and Control of Meningococcal Disease in Canada: A Long, Complex, and Unfinished Story

The epidemiology of meningococcal disease in Canada has been punctuated by outbreaks caused by serogroup A strains in the 1940s, virulent serogroup C clones from 1985 to 2001, a serogroup B clone in Quebec from 2003 to 2014, and more recently a W clone in British Columbia. Region- and province-wide immunization campaigns have been implemented to control these outbreaks using meningococcal C polysaccharide and conjugate vaccines, a quadrivalent ACWY conjugate vaccine, and a serogroup B protein-based vaccine. Meningococcal C conjugate vaccines have been included in routine immunization programs for children, and ACWY conjugate vaccines have been included in school-based programs for adolescents in most jurisdictions. In contrast, serogroup B protein-based vaccines were only recommended and used for high-risk individuals and to control outbreaks. Currently, the immunization schedules adopted in provinces and territories are not uniform. This is not explained by notable epidemiologic differences. Publicly funded immunization programs are the result of a complex decision-making process. Political factors including public opinion, media attention, interest groups' advocacy campaigns, decision-makers' priorities and budgetary constraints have played important roles in shaping meningococcal programs in Canada, and this should be recognized. As the recent occurrence of outbreaks caused by virulent W clones shows, continued investments in epidemiological surveillance at both the provincial and national levels are necessary, so there can be early warning and informed decisions can be made.

To LP or not to LP? Identifying the Etiology of Pediatric Meningitis

Introduction of conjugate vaccines against Haemophilus influenzae type b, Streptococcus pneumoniae, and Neisseria meningitidis has led to a substantial reduction in cases of acute bacterial meningitis in countries with high routine childhood immunization coverage. The majority of children hospitalized with meningitis in high-income countries have viral or aseptic meningitis and do not require antibiotic treatment. Cerebrospinal fluid analysis is irreplaceable in appropriately diagnosing and treating bacterial meningitis and avoiding unnecessary antibiotics and prolonged hospitalizations in children with viral meningitis. New diagnostic tests have improved detection of bacterial and viral pathogens in cerebrospinal fluid, underscoring the importance of promptly performing lumbar puncture when meningitis is suspected. This article provides an overview of acute bacterial and viral meningitis in children, focusing on the changing epidemiology, the advantages and limitations of conventional and newer diagnostic methods, and considerations for clinical practice.

Vaccination strategies for the prevention of meningococcal disease

Routine prophylactic vaccination and mass vaccination strategies have been used to control both endemic and epidemic disease caused by Neisseria meningitidis globally. This review discusses real-world examples of these vaccination strategies, their implementation, and outcomes of these efforts, with the overall goal of providing insights on how to achieve optimal control of meningococcal disease through vaccination in varied settings. Tailoring immunization programs to fit the needs of the target population has the potential to optimally reduce disease incidence.

Impact of meningococcal C conjugate vaccination programs with and without catch-up campaigns in adolescents: Lessons learned from Bahia, Brazil

The significant increase in the incidence rates and ongoing outbreaks of serogroup C meningococcal (MenC) disease, associated with the sequence type-103 complex, motivated the incorporation of the meningococcal C conjugate (MCC) vaccine in the routine immunization program in the State of Bahia, Brazil in early 2010, targeting children younger than 5 years of age. In its capital, Salvador, the program also included a catch-up campaign for individuals 10-24 years of age. We performed an observational, ecological study, analyzing data collected from 2007 to 2015, to compare the impact of these two immunization strategies on meningococcal disease incidence and mortality rates. In Salvador, following the vaccination program, a dramatic early impact on MenC disease and mortality rates could be observed, with significant reductions in incidence rates of MenC disease in all age groups, including individuals that were too old to have been vaccinated, indicating the presence of herd protection. Compared to the pre-vaccine period, a virtual disappearance of MenC disease was observed in 2015. However, in the state of Bahia (excluding the city of Salvador), no herd protection could be observed, with significant impact only among vaccine-eligible children within 5 years of introduction of the MCC vaccination program. These results highlight the importance of catch-up campaigns, including adolescents and young adults, to induce herd protection compared to immunization strategies restricted to infants and young children. This information is crucial for identifying optimal immunization policies and future strategies, focused on adolescents, to optimize the impact of MCC vaccination programs.

Impact and effectiveness of meningococcal vaccines: a review

Objectives.

To summarize and critically evaluate the evidence on the impact and effectiveness of meningococcal vaccination programs around the world in order to inform decisionmaking in Latin America and the Caribbean.

Methods.

A review of the literature was conducted following several components of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. PubMed Central® was searched for papers published in any language from January 1999 – March 2017.

Results.

In all, 32 studies were included, most of which evaluated the meningococcal C conjugate vaccine. Fourteen studies measured effectiveness and 30 measured impact. The effectiveness of polysaccharide vaccines was 65% – 83.7% (different age groups), while the effectiveness of the conjugate vaccines was 66% – 100%. Incidence decline of laboratory-confirmed meningococcal disease for the conjugate vaccine ranged from 77% – 100% among different ages groups. The only study that evaluated the protein subunit vaccine reported a vaccine effectiveness of 82.9%.

Conclusions.

The studies reviewed show impact and effectiveness of both polysaccharide vaccines and conjugate vaccines on vaccine-serogroup meningococcal disease. The conjugate vaccines, however, show higher impact and effectiveness with longer-lasting protection over the polysaccharide vaccines. Given the variance in potential use of a meningococcal vaccine, epidemiological surveillance systems should be strengthened to inform national decisions.

Attitudes of Swiss Health Care Providers Toward Childhood Immunizations

BACKGROUND

INFOVAC is a network providing information about immunization issues to health professionals. The aim of this study was to assess the attitude of INFOVAC subscribers toward the current Swiss immunization schedule, potential modifications, and current and hypothetical immunization practices regarding their own children.

METHODS

In March 2015, a Web-based survey was sent to 4260 physicians and pharmacists subscribed to INFOVAC. Participation was anonymous and voluntary. The following information was obtained: (1) current immunization status of own children; (2) which immunizations would currently be accepted for a hypothetical own child and (3) attitudes toward potential modifications of the Swiss immunization schedule. Descriptive methods and multivariate models to correct for covariables were used for data analysis.

RESULTS

Nine hundred and fifty-five valid questionnaires were received: 886/3704 (23.9%) from physicians and 69/556 (12.4%) from pharmacists. Current (>95%) and hypothetical (>99%) immunization rates were high for diphtheria, tetanus, pertussis, poliomyelitis and measles-mumps-rubella. Most pediatricians (61%) would support more vaccines for their children than currently recommended by the Swiss immunization advisory committee, whereas about 50% of other physicians and pharmacists would decline at least one of the recommended immunizations, most frequently varicella, pneumococcal or meningococcal C conjugate vaccines. Strong general support was expressed for the expansion of human papillomavirus immunization to males, acceleration of the measles-mumps-rubella schedule and a 2 + 1 instead of 3 + 1 diphtheria-tetanus-pertussis, acellular-inactivated poliomyelitis vaccine (DTPa-IPV)/Haemophilus influenzae type b ± hepatitis B virus (HBV) schedule.

CONCLUSIONS

Survey participants generally demonstrated a positive attitude toward immunization, with pediatricians being the most progressive subgroup with the largest percentage of participants (63.1%) neither declining nor postponing any recommended immunization.

Cost-effectiveness of alternate strategies for childhood immunization against meningococcal disease with monovalent and quadrivalent conjugate vaccines in Canada

BACKGROUND

Public health programs to prevent invasive meningococcal disease (IMD) with monovalent serogroup C meningococcal conjugate vaccine (MCV-C) and quadrivalent meningococcal conjugate vaccines (MCV-4) in infancy and adolescence vary across Canadian provinces. This study evaluated the cost-effectiveness of various vaccination strategies against IMD using current and anticipated future pricing and recent epidemiology.

METHODS

A cohort model was developed to estimate the clinical burden and costs (CAN$2014) of IMD in the Canadian population over a 100-year time horizon for three strategies: (1) MCV-C in infants and adolescents (MCV-C/C); (2) MCV-C in infants and MCV-4 in adolescents (MCV-C/4); and (3) MCV-4 in infants (2 doses) and adolescents (MCV-4/4). The source for IMD incidence was Canadian surveillance data. The effectiveness of MCV-C was based on published literature. The effectiveness of MCV-4 against all vaccination regimens was assumed to be the same as for MCV-C regimens against serogroup C. Herd effects were estimated by calibration to estimates reported in prior analyses. Costs were from published sources. Vaccines prices were projected to decline over time reflecting historical procurement trends.

RESULTS

Over the modeling horizon there are a projected 11,438 IMD cases and 1,195 IMD deaths with MCV-C/C; expected total costs are $597.5 million. MCV-C/4 is projected to reduce cases of IMD by 1,826 (16%) and IMD deaths by 161 (13%). Vaccination costs are increased by $32 million but direct and indirect IMD costs are projected to be reduced by $46 million. MCV-C/4 is therefore dominant vs. MCV-C/C in the base case. Cost-effectiveness of MCV-4/4 was $111,286 per QALY gained versus MCV-C/4 (2575/206 IMD cases/deaths prevented; incremental costs $68 million).

CONCLUSIONS

If historical trends in Canadian vaccines prices continue, use of MCV-4 instead of MCV-C in adolescents may be cost-effective. From an economic perspective, switching to MCV-4 as the adolescent booster should be considered.

Multicomponent meningococcal B vaccination (4CMenB) of adolescents and college students in the United States

Meningococcal disease is rare, easily misdiagnosed, and potentially deadly. Diagnosis in the early stages is difficult and the disease often progresses extremely rapidly. In North America, the incidence of invasive meningococcal disease (IMD) is highest in infants and young children, with a secondary peak in adolescents, a population predominantly responsible for the carriage of disease. Neisseria meningitidis serogroup B (MenB) accounts for a large proportion of meningococcal disease in North America, with documented outbreaks in three universities in the United States (US) during 2008-2013. Vaccination is the most effective way to protect against this aggressive disease that has a narrow timeframe for diagnosis and treatment. 4CMenB is a multi-component vaccine against MenB which contains four antigenic components. We describe in detail the immunogenicity and safety profile of 4CMenB based on results from four clinical trials; the use of 4CMenB to control MenB outbreaks involving vaccination at two US colleges during outbreaks in 2013-2014; and the use of 4CMenB in a Canadian mass vaccination campaign to control the spread of MenB disease. We discuss the reasons why adolescents should be vaccinated against MenB, by examining both the peak in disease incidence and carriage. We consider whether herd protection may be attained for MenB, by discussing published models and comparing with meningitis C (MenC) vaccines. In conclusion, MenB vaccines are now available in the US for people aged 10-25 years, representing an important opportunity to reduce the incidence of IMD in the country across the whole population, and more locally to combat MenB outbreaks.

Acute bacterial meningitis in adults

Over the past several decades, the incidence of bacterial meningitis in children has decreased but there remains a significant burden of disease in adults, with a mortality of up to 30%. Although the pathogenesis of bacterial meningitis is not completely understood, knowledge of bacterial invasion and entry into the CNS is improving. Clinical features alone cannot determine whether meningitis is present and analysis of cerebrospinal fluid is essential for diagnosis. Newer technologies, such as multiplex PCR, and novel diagnostic platforms that incorporate proteomics and genetic sequencing, might help provide a quicker and more accurate diagnosis. Even with appropriate antimicrobial therapy, mortality is high and so attention has focused on adjunctive therapies; adjunctive corticosteroids are beneficial in certain circumstances. Any further improvements in outcome are likely to come from either modulation of the host response or novel approaches to therapy, rather than new antibiotics. Ultimately, the best hope to reduce the disease burden is with broadly protective vaccines.

The Global Evolution of Meningococcal Epidemiology Following the Introduction of Meningococcal Vaccines

Invasive meningococcal disease (IMD) caused by Neisseria meningitidis is associated with high morbidity and mortality. Although IMD incidence is highest in infants, a second peak occurs in adolescents/young adults. The incidence of IMD and the predominant disease-causing meningococcal serogroups vary worldwide. Epidemiologic data have guided the development of meningococcal vaccines to reduce the IMD burden. In Europe, serogroup C IMD has been substantially reduced since the introduction of a serogroup C conjugate vaccine. Serogroup B predominates in Europe, although cases of serogroup Y IMD have been increasing in recent years. In the United States, declines in serogroup C and Y disease have been observed in association with the introduction of quadrivalent (serogroups ACWY) meningococcal conjugate vaccines; serogroup B persists and is now the most common cause of outbreak associated disease. In the African meningitis belt, a conjugate vaccine for serogroup A has been effective in decreasing meningitis associated with that serogroup. Outbreaks of the previously rare serogroup X disease have been reported in this region since 2006. In recent years, outbreaks of serogroup B IMD, for which vaccines have only recently been approved by the U.S. Food and Drug Administration and the European Medicines Agency, have occurred in Europe and the United States. Targeting meningococcal vaccination to adolescents/young adults may reduce the morbidity and mortality associated with IMD and has the potential to impact the larger community through herd benefits.

Vaccines for Prevention of Group B Meningococcal Disease: Not Your Father's Vaccines

For decades, there was no licensed vaccine for prevention of endemic capsular group B meningococcal disease, despite the availability of vaccines for prevention of the other most common meningococcal capsular groups. Recently, however, two new vaccines have been licensed for prevention of group B disease. Although immunogenic and considered to have an acceptable safety profile, there are many scientific unknowns about these vaccines, including effectiveness against antigenically diverse endemic meningococcal strains; duration of protection; whether they provide any herd protection; and whether there will be meningococcal antigenic changes that will diminish effectiveness over time. In addition, these vaccines present societal dilemmas that could influence how they are used in the U.S., including high vaccine cost in the face of a historically low incidence of meningococcal disease. These issues are discussed in this review.

Comparison of Phenotypic and Genotypic Approaches to Capsule Typing of Neisseria meningitidis by Use of Invasive and Carriage Isolate Collections

Neisseria meningitidis serogroup B (MnB) is a leading cause of bacterial meningitis; however, MnB is most commonly associated with asymptomatic carriage in the nasopharyngeal cavity, as opposed to the disease state. Two vaccines are now licensed for the prevention of MnB disease; a possible additional benefit of these vaccines could be to protect against disease indirectly by disrupting nasopharyngeal carriage (e.g., herd protection). To investigate this possibility, accurate diagnostic approaches to characterize MnB carriage isolates are required. In contrast to invasive meningococcal disease (IMD) isolates, which can be readily serogrouped, carriage isolates often lack capsule expression, making standard phenotypic assays unsuitable for strain characterization. Several antibody-based methods were evaluated for their abilities to serogroup isolates and were compared with two genotyping methods (real-time PCR [rt-PCR] and whole-genome sequencing [WGS]) to identify which approach would most accurately ascertain the polysaccharide groups associated with carriage isolates. WGS and rt-PCR were in agreement for 99% of IMD isolates, including those with coding sequences for MnB, MnC, MnW, and MnY, and the phenotypic methods correctly identified serogroups for 69 to 98% of IMD isolates. In contrast, only 47% of carriage isolates were groupable by genotypic methods, due to mutations within the capsule operon; of the isolates identified by genotypic methods, ≤43% were serogroupable with any of the phenotypic methods tested. These observations highlight the difficulties in the serogrouping and capsular genogrouping of meningococcal carriage isolates. Based on our findings, WGS is the most suitable approach for the characterization of meningococcal carriage isolates.

Vaccines for prevention of group B meningococcal disease: Not your father's vaccines

For decades, there was no licensed vaccine for prevention of endemic capsular group B meningococcal disease, despite the availability of vaccines for prevention of the other most common meningococcal capsular groups. Recently, however, two new vaccines have been licensed for prevention of group B disease. Although immunogenic and considered to have an acceptable safety profile, there are many scientific unknowns about these vaccines, including effectiveness against antigenically diverse endemic meningococcal strains; duration of protection; whether they provide any herd protection; and whether there will be meningococcal antigenic changes that will diminish effectiveness over time. In addition, these vaccines present societal dilemmas that could influence how they are used in the U.S., including high vaccine cost in the face of a historically low incidence of meningococcal disease. These issues are discussed in this review.

Parents' and adolescents' willingness to be vaccinated against serogroup B meningococcal disease during a mass vaccination in Saguenay-Lac-St-Jean (Quebec)

A mass vaccination campaign with the 4CMenB vaccine (Bexsero®; Novartis Pharmaceutical Canada Inc) was launched in a serogroup B endemic area in Quebec. A telephone survey was conducted to assess parental and adolescent opinions about the acceptability of the vaccine. Intent to receive the vaccine or vaccine receipt was reported by the majority of parents (93%) and adolescents (75%). Meningitis was perceived as being a dangerous disease by the majority of parents and adolescents. The majority of respondents also considered the 4CMenB vaccine to be safe and effective. The main reason for positive vaccination intention or behaviour was self-protection, while a negative attitude toward vaccination in general was the main reason mentioned by parents who did not intend to have their child vaccinated. Adolescents mainly reported lack of interest, time or information, and low perceived susceptibility and disease severity as the main reasons for not intending to be vaccinated or not being vaccinated.

Outcomes of invasive meningococcal disease in adults and children in Canada between 2002 and 2011: a prospective cohort study

BACKGROUND

Neisseria meningitidis causes 500 000 cases of septicemia and meningitis worldwide annually, with approximately 200 cases in Canada each year. Previous studies describe a case-fatality rate of 5%-15% and up to 20% of survivors suffering from long-term disability.

METHODS

This study was performed in Canada between 2002 and 2011; the study area included >50% of the country's population. We identified risk factors associated with death and the development of complications in children and adults admitted to hospital with confirmed invasive meningococcal disease (IMD). Clinical information was obtained from hospital records. Risk factors for death and complications were analyzed by univariate and multivariable analyses.

RESULTS

Of 868 individuals hospitalized with IMD, there were 73 deaths (8.4%) and 157 (18%) developed complications. The most common complications were hearing loss (5.4%), skin scarring (5.4%), amputation (3.4%), renal dysfunction (2.6%), and seizures (2.5%). Mortality was independently associated with shock (adjusted odds ratio [aOR], 23.30; P<.0001), age (aOR, 1.02 per 1-year increased age; P<.0001), symptom onset within 24 hours of admission (aOR, 1.80; P=.0471), and admission to the intensive care unit (aOR, 0.41; P=.0196). Development of complications was independently associated with seizures (aOR, 4.55; P<.0001), shock (aOR, 3.10; P<.0001), abnormal platelet count (aOR, 2.14; P=.0002), bruising (aOR, 3.17; P=.0059), abnormal white blood cell count (aOR, 0.52; P=.0100), and prior antibiotic exposure (aOR, 0.27; P=.0273).

CONCLUSIONS

Outcomes following IMD remain poor in this resource-rich setting in the 21st century. These data identify priorities for clinical management of adults and children with IMD, and provide prognostic information for affected patients and their families and cost-effectiveness analyses for meningococcal vaccine programs.