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

Geographical and temporal variations of serogroups and clonal types of Neisseria meningitidis involved in culture-confirmed invasive meningococcal disease in Canada, 2015-2023

Introduction. Invasive meningococcal disease (IMD) is a nationally notifiable illness in Canada due to its potential severity and transmissibility. Vaccination strategies differ by province/territory and are informed by changes in the antigenic characteristics of circulating strains.Gap Statement. Though IMD statistics are tracked at a provincial/territorial level, there is a lack of published data characterizing trends in the epidemiology of this disease at a national level.Aim. To examine the epidemiology of culture-confirmed IMD in Canada during the period of 2015-2023.Methodology. Meningococcal isolates sent to the National Microbiology Laboratory Branch between 2015 and 2023 as part of routine national surveillance were characterized for serogroup by bacterial agglutination and genetic methods. Clonal analysis was done by MLST. Demographic information was derived from requisition forms accompanying the samples.Results. The proportion of IMD caused by serogroup W meningococci (MenW) in 2015-2023 was 30.0% with more (62.9%) MenW cases detected in western provinces. Serogroup B meningococci (MenB) IMD was more common (53.4%) in Quebec and Atlantic Canada. Clonal analysis reveals 168 distinct sequence types between 2015 and 2023, with 103 belonging to MenB. The average age of MenB cases during this time was 29.1 years, significantly younger than serogroup C (MenC) (45.3 years), serogroup Y (MenY) (48.3 years) and MenW (43.0 years) patients. Additionally, 31.5% of MenB and 21.7% of MenC IMD isolates were collected from cerebrospinal fluid (CSF) or brain samples, which were significantly higher than that for MenY (12.2%) and MenW (7.3%) isolates.Conclusions. Results from this and previous studies showed temporal and geographical variations in the serogroups causing IMD in Canada. MenB also showed the most genetic diversity, caused IMD in a significantly younger population and was more often isolated from CSF and brain samples than other serogroups.

A National Advisory Committee on Immunization (NACI) update on invasive meningococcal disease (IMD) epidemiology and program-relevant considerations for preventing IMD in individuals at high risk of exposure

Following recent outbreaks of invasive meningococcal disease (IMD) in Canada and updates to provincial vaccination guidelines, the National Advisory Committee on Immunization (NACI) conducted a targeted review of evidence with a focus on immunization of adolescents and young adults. NACI reviewed national and international immunization recommendations for populations at high-risk of IMD, national IMD epidemiology and program-relevant considerations. Given the varied IMD epidemiology, NACI determined that recommending a pan-Canadian targeted program is currently challenging and that regional programs may be better suited to prevent IMD in population groups considered to be at high-risk of exposure. Further data is needed to ascertain contemporary risk factors for IMD (including activities and settings associated with bacterial acquisition, carriage and transmission) and estimate the true cost of meningococcal vaccine-preventable infections in Canada. To support provinces and territories in their decision-making, an outline of program-relevant elements for provincial and territorial consideration is provided.

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.

Characterization of invasive meningococcal disease case isolates in Atlantic Canada, 2014 to 2020: spatial-temporal variations of clones and predicted meningococcal B vaccine coverage

Introduction. Invasive meningococcal disease (IMD) caused by Neisseria meningitidis may show temporal and geographical changes in both the epidemiology and the characteristics of the strains involved.Gap statement. A study that examined invasive N. meningitidis causing IMD in Atlantic Canada from 2009 to 2013 was published in 2014. Data from subsequent years have not been described.Aim. This study examined the molecular epidemiology of IMD in four Atlantic Provinces of Canada as well as potential serogroup B (MenB) vaccine coverage.Methods. Individual IMD case isolates recovered from 2014 to 2020 were analysed for serotype and serosubtype antigens as well as by whole-genome sequencing (WGS) for prediction of potential MenB vaccine coverage.Results. Of the 56 IMD isolates, 42, 8, 5 and 1 were MenB, serogroup Y, serogroup W (MenW) and serogroup C, respectively. Geographical differences in the distribution of MenB clones revealed concentration of sequence type (ST)-269 clonal complex (cc) and ST-60 cc in Newfoundland and Labrador, while ST-41/44 cc (particularly ST-154) was predominantly found in New Brunswick and Nova Scotia. Core genome multi-locus sequence typing (cgMLST) also separated the New Brunswick and Nova Scotia ST-154 isolates into two clusters, with differences in their nhba and penA alleles. Furthermore, cgMLST also separated the ST-269 cc isolates in Atlantic Canada into the ST-1611 and the ST-269/ST-8924 clusters, with the latter showing high similarity to the ST-269 that first emerged in the Province of Quebec. Genetic Meningococcal Antigen Typing System showed that 54.8 % of MenB were predicted to be covered by the MenB vaccine Bexsero, with a further 38.1 % potentially covered by virtue of the presence of genes that encoded factor H-binding protein variant 1 proteins. Meningococcal deduced vaccine antigen reactivity predicted from WGS data showed that 95.3 % of MenB were covered by Trumenba. Four cases of IMD due to MenW ST-11 cc were also identified, with the first case found in 2018.Conclusions. This study provided evidence concerning the dynamics of N. meningitidis strains causing IMD in Atlantic Canada, with both geographical and temporal differences found. MenB vaccine appeared to provide good coverage of MenB IMD, especially towards the predominant strain of ST-154.

Meningococcal Disease Outbreaks: A Moving Target and a Case for Routine Preventative Vaccination

Outbreaks of invasive meningococcal disease (IMD) are unpredictable, can be sudden and have devastating consequences. We conducted a non-systematic review of the literature in PubMed (1997-2020) to assess outbreak response strategies and the impact of vaccine interventions. Since 1997, IMD outbreaks due to serogroups A, B, C, W, Y and X have occurred globally. Reactive emergency mass vaccination campaigns have encompassed single institutions (schools, universities) through to whole sections of the population at regional/national levels (e.g. serogroup B outbreaks in Saguenay-Lac-Saint-Jean region, Canada and New Zealand). Emergency vaccination responses to IMD outbreaks consistently incurred substantial costs (expenditure on vaccine supplies, personnel costs and interruption of other programmes). Impediments included the limited pace of transmission of information to parents/communities/healthcare workers; issues around collection of informed consents; poor vaccine uptake by older adolescents/young adults, often a target age group; issues of reimbursement, particularly in the USA; and difficulties in swift supply of large quantities of vaccines. For serogroup B outbreaks, the need for two doses was a significant issue that contributed substantially to costs, delayed onset of protection and non-compliance with dose 2. Real-world descriptions of outbreak control strategies and the associated challenges systematically show that reactive outbreak management is administratively, logistically and financially costly, and that its impact can be difficult to measure. In view of the unpredictability, fast pace and potential lethality of outbreak-associated IMD, prevention through routine vaccination appears the most effective mitigation tool. Highly effective vaccines covering five of six disease-causing serogroups are available. Preparedness through routine vaccination programmes will enhance the speed and effectiveness of outbreak responses, should they be needed (ready access to vaccines and need for a single booster dose rather than a primary series).

Use of Cost-Effectiveness Analyses for Decisions About Vaccination Programs for Meningococcal Disease in the United States, United Kingdom, The Netherlands, and Canada

INTRODUCTION

Meningococcal vaccines to protect against invasive meningococcal disease (IMD) vary in terms of vaccine technology and serogroup coverage (Polysaccharide MnACWY, conjugated C and ACWY, outer membrane vesicle-based or protein-based B vaccines), and the national recommendations for each of them vary in terms of target population and number of doses. We sought to understand factors associated with the evolution of meningococcal vaccination program recommendations in four countries with formal evaluation processes: the UK, US, the Netherlands, and Canada.

AREAS COVERED

A targeted review of published literature and internet sources for the four countries relating to meningococcal vaccination decision-making was conducted. The review focused on the impact of cost-effectiveness analyses on vaccine policy decisions and the extent to which variation in incidence of IMD and its potential catastrophic consequences influenced policy decisions.The evolution of meningococcal vaccine recommendations in the four countries was mainly driven by changes in vaccine availability and changes in serogroup incidence. Public pressure due to the catastrophic nature of IMD influenced recommendations. The role of cost-effectiveness analyses varied across the 4 countries.

EXPERT OPINION

The value of implementing meningococcal vaccination programs should be assessed using factors beyond those included in traditional cost-effectiveness analyses.

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.