Meningococcal serogroup Y emergence in Europe: update 2011

Temporal variations in the serogroup distribution of invasive meningococcal disease in Quebec, Canada, due to emerging unique clade of serogroup Y strain belonging to the Sequence Type-23 clonal complex

OBJECTIVE

To identify recent trends in invasive meningococcal diseases (IMD) in Quebec, Canada, with a focus on MenY cases and MenY strains.

METHODS

IMD cases and MenY strains from January 1, 2015 to August 11, 2023 were analyzed for clonal analysis and prediction of susceptibility to MenB vaccines. MenY strains of ST-23 CC from Quebec were analyzed with global MenY strains by core-genomic multi-locus sequence typing (cg-MLST).

RESULTS

Since 2015 the serogroup distribution of IMD in Quebec has shifted from predominantly MenB to mainly MenY, with most (80.9 %) of the latter belonging to ST-23 CC. The median age of MenY cases due to ST-23 CC were statistically younger than MenY cases due to non-ST-23 CC. MenY of ST-23 CC showed genetic diversity and the major genetic cluster were similar to the Swedish Y1 strain. The increase in invasive MenY disease in Quebec was due to a sub-clade of Lineage 23.1 which caused an elevated proportion of severe disease in young adults.

CONCLUSION

The increase in invasive MenY disease in Quebec, Canada was driven by the expansion of a sub-clade of Lineage 23.1 in young adults. Currently available quadrivalent A,C,W,Y-conjugate meningococcal vaccines were predicted to provide protection against these strains.

An Outbreak of Serogroup Y Meningococcal Meningitis in a Private Secondary Vocational School - Guangzhou City, Guangdong Province, China, 2023

What is already known about this topic?

The inclusion of meningococcal vaccines in the National Immunization Program (NIP) over several years has significantly reduced the incidence of meningococcal meningitis in China to historic lows. Worldwide, there has been a diversification of meningococcal serogroups, leading to a shift in dominant serogroups in China from serogroup A to serogroups C and B, accompanied by a rise in reports of serogroups Y and W.

What is added by this report?

An outbreak of serogroup Y Neisseria meningitidis (Nm) in a secondary vocational school involved a single confirmed severe case and 24 individuals with laboratory-confirmed Nm carriage. Epidemiological investigation revealed that the outbreak was localized to the classroom of the confirmed case. Prolonged close contact within a confined space was identified as a significant risk factor for Nm transmission. The genotype sequence identified was type 1655 (ST-1655), which is categorized under clonal complex 23 (CC-23) and bears resemblance to 8 previously confirmed cases of serogroup Y meningococcal meningitis within Guangdong Province. This suggests that serogroup Y infections continue to sporadically emerge and have become prevalent strains.

What are the implications for public health practice?

This outbreak underscores the critical need to enhance surveillance of meningococcal serogroups and population carrier, and advocate for vaccination with MenY-containing vaccines.

A policy review of the introduction of the MenACWY vaccine in toddlers across multiple countries

INTRODUCTION

Immunization is the best strategy to protect individuals from invasive meningococcal disease (IMD). To support decision-making around immunization, this paper considers what has led four countries and regions of two more to introduce the quadrivalent MenACWY vaccine in toddlers (ages 12-24 months).

AREAS COVERED

A narrative literature review was conducted to identify countries that have introduced a MenACWY vaccination program for toddlers. Information from peer-reviewed publications, reports, and policy documents for each identified country was extracted. Australia, Chile, the Netherlands, Switzerland, and regions of Italy and Spain have introduced the MenACWY vaccine in their toddler programs, driven by the rising incidence of MenW and MenY and the vaccine's ability to provide protection against other serogroups. Australia and the Netherlands considered the economic impacts of implementing a MenACWY toddler vaccination program. Vaccination uptake and effects are reported for three countries; however, in two, isolating the vaccine's effect from the collateral effect of COVID-related measures is difficult.

EXPERT OPINION

Increased convergence of vaccination policies and programs is needed internationally, as IMD recognizes no borders.PL AIN LANGUAGE SUMMARYVaccination is the best defense against meningitis, a deadly disease. While someone of any age can contract it, children 0-24 months of age are disproportionately affected. The increasing number of cases of meningitis has led four countries plus regions of two more to introduce into their vaccination schedules for toddlers (ages 12-24 months) a vaccine that protects against four different serogroups rather than one serogroup alone. This paper considers what has driven that shift.

Australian Meningococcal Surveillance Programme Annual Report, 2020

Abstract

Invasive meningococcal disease (IMD) is a notifiable disease in Australia, and both probable and laboratory-confirmed cases of IMD are reported to the National Notifiable Diseases Surveillance System (NNDSS). In 2020, there were 90 notifications of IMD, the lowest number documented since records began in the NNDSS in 1991. Of these, 97% (87/90) were laboratory-confirmed cases, with 70% (61/87) confirmed by bacterial culture and 30% (26/87) by nucleic acid amplification testing. The serogroup was determined for 85/87 laboratory-confirmed cases of IMD: serogroup B (MenB) accounted for 64% of infections (54/85); MenW for 19% (16/85); MenY for 16% (14/85); and MenC 1.2% (1/85). Fine typing was available on 60/85 (71%) of cases with serogroup determined; of the typed MenW, all were PorA antigen type P1.5,2 and sequence type 11, the hypervirulent strain reported in recent outbreaks in Australia and overseas. The primary peaks of IMD notifications in Australia in 2020 were observed in infants less than 1 year (16/87, 18%) and in adults aged 45-64 years (14/87, 16%). MenB infections predominated in those aged less than 5 years and 15-19 years; MenW and MenY infections predominated in those aged 45 years or more. All 61 IMD isolates were tested for antimicrobial susceptibility: none were penicillin resistant; however, 56/61 (92%) had decreased susceptibility to penicillin. All isolates were susceptible to ceftriaxone, ciprofloxacin and rifampicin.

Genomic Surveillance of a Globally Circulating Distinct Group W Clonal Complex 11 Meningococcal Variant, New Zealand, 2013-2018

Genomic surveillance is an essential part of effective disease control, enabling identification of emerging and expanding strains and monitoring of subsequent interventions. Whole-genome sequencing was used to analyze the genomic diversity of all Neisseria meningitidis isolates submitted to the New Zealand Meningococcal Reference Laboratory during 2013–2018. Of the 347 isolates submitted for whole-genome sequencing, we identified 68 sequence types belonging to 18 clonal complexes (CC). The predominant CC was CC41/44; next in predominance was CC11. Comparison of the 45 New Zealand group W CC11 isolates with worldwide representatives of group W CC11 isolates revealed that the original UK strain, the 2013 UK strain, and a distinctive variant (the 2015 strain) were causing invasive group W meningococcal disease in New Zealand. The 2015 strain also demonstrated increased resistance to penicillin and has been circulating in Canada and several countries in Europe, highlighting that close monitoring is needed to prevent future outbreaks around the world.

Australian Meningococcal Surveillance Programme annual report, 2019

Invasive meningococcal disease (IMD) is a notifiable disease in Australia, and both probable and laboratory-confirmed cases of IMD are reported to the National Notifiable Diseases Surveillance System (NNDSS). In 2019, there were 206 notifications of IMD. Of these, 202 were laboratory-confirmed cases analysed by the reference laboratories of the Australian National Neisseria Network (NNN). Of the 202 laboratory-confirmed cases of IMD, 167 were confirmed by bacterial culture and 35 by nucleic acid amplification testing, and all had the serogroup determined. Fine typing was available on 146 samples (146/202, 72%). Neisseria meningitidis serogroup B (MenB) infections accounted for 50.0% (101/202); MenW for 26.2% (53/202); MenY for 20.8% (42/202) and MenC for 3.0% of cases (6/202). Of the MenW cases, 88% were PorA antigen type P1.5,2, and 65% of these (24/37) were sequence type 11, the hypervirulent strain reported in recent outbreaks in Australia and overseas. The primary peaks of IMD notifications in Australia in 2019 were observed in infants less than 1 year of age (36/202, 18%) and in adults aged 65 years or older (39/202, 19%). MenB infections predominated in those aged less than 5 years and those aged 15-19 years, whereas MenW and MenY infections predominated in those aged 45 years or more. All 167 IMD isolates were tested for antimicrobial susceptibility. One isolate out of these 167 (0.6%) was resistant to penicillin with an MIC ≥ 1mg/L; 154/167 isolates (92%) had decreased susceptibility to penicillin. All isolates were susceptible to ceftriaxone and ciprofloxacin, and one isolate was resistant to rifampicin.

Recent changes of invasive meningococcal disease in France: arguments to revise the vaccination strategy in view of those of other countries

In France, the incidence of invasive meningococcal disease (IMD) is around 1/100,000, with the following trends over the 2011-2018 period: a leading role of group B in subjects <15 years, a decrease of group C among <1 year since 2017, an increase of group W in all age groups including subjects <1 year since 2014 and a positive correlation between group Y and age group. In Europe, vaccination progressed with conjugate ACWY vaccines and proteins-based B vaccines. Their benefit-risk-cost balance is however not so obvious for area at low incidence (<2/100,000), explaining tremendous variations between countries, from no recommendation to recommend all available vaccines. In France, the calendar still includes only C with a good adhesion in infants but a fiasco of the catch-up campaign in adolescents and young adults. In Europe, it is time to consider not only national epidemiology but also trends in the neighborhood. The increase of group W cases encourages switching C to ACWY vaccine both in infants and adolescents. It is also time to protect infants with B vaccine. Large pedagogy on the disease is required to increase the adhesion to the vaccination and to recognize and treat earlier the residual cases.

Australian Meningococcal Surveillance Programme annual report, 2018

Invasive meningococcal disease (IMD) is a notifiable disease in Australia, and both probable and laboratory-confirmed cases of IMD are reported to the National Notifiable Diseases Surveillance System (NNDSS). In 2018, there were 281 IMD cases notified to the NNDSS. Of these, 278 were laboratory-confirmed cases analysed by the reference laboratories of the Australian National Neisseria Network (NNN). On investigation, the serogroup was able to be determined for 98.6% (274/278) of laboratory-confirmed cases. Serogroup B infections accounted for 44.2% of cases (123 cases); serogroup W for 36.3% of cases (101 cases); serogroup Y infections for 15.8% (44 cases) and serogroup C 1.4% (4 cases); and there were two unrelated cases (0.7%) of IMD attributable to serogroup E. Using molecular methods, 181/278 IMD cases were able to be typed. Of note was that 89% of typed serogroup W IMD cases (66/74) were porA antigen type P1.5,2; of this number, 44% (29/66) were sequence type 11, the hypervirulent strain reported in recent outbreaks in Australia and overseas. The primary age peak of IMD in Australia in 2018 was again observed in adults aged 45 years or more; a secondary disease peak was observed in children and infants aged less than 5 years. Serogroup B infections predominated in those aged less than 5 years, whereas serogroup W and serogroup Y infections predominated in those aged 45 years or more. Of the IMD isolates tested for antimicrobial susceptibility, 1.4% (3/210) were resistant to penicillin with an MIC ≥ 1 mg/L, and decreased susceptibility to penicillin was observed in a further 93.8% (197/210) of isolates. All isolates were susceptible to ceftriaxone and rifampicin; there was one isolate less susceptible to ciprofloxacin.

Australian Meningococcal Surveillance Programme annual report, 2017

In 2017, there were 374 laboratory-confirmed cases of invasive meningococcal disease (IMD) analysed by the Australian National Neisseria Network. This was the highest number of laboratory-confirmed cases since 2003. Probable and confirmed cases of IMD are notifiable in Australia; there were 379 IMD cases notified to the National Notifiable Diseases Surveillance System in 2017, the highest number reported since 2005. Meningococcal sero-grouping was determined for 98% (367/374) of laboratory-confirmed IMD cases. Serogroup B infections accounted for 137 cases (37%). The number of serogroup W infections (141 cases, 38%) in 2017 was the highest since the Australian Meningococcal Surveillance Programme (AMSP) began. In addition, the number and proportion of serogroup Y infections (75 cases, 20%) was also the highest recorded by the AMSP. Molecular typing results were available for 315 of the 374 IMD cases (83%). Of the serogroup W IMD strains that were able to be genotyped, 97% (125/129) had the PorA antigen encoding gene type P1.5,2 and of these, 59% (74/125) were sequence type 11, the same type as the hypervirulent serogroup W strain that has been circulating in the UK and South America since 2009. The primary IMD age peak was observed in adults aged 45 years or more, whilst secondary disease peaks were observed in those aged less than 5 years. Serogroup B infections predominated in the age group 15-19 years. Serogroup W infections predominated in those aged 65 years or more. Serogroup Y infections were predominately seen in adults aged 45 years or more. Of the IMD isolates tested for antimicrobial susceptibility, 5.1% (14/276) were resistant to penicillin; decreased susceptibility to penicillin was observed in a further 89% (247/276) of isolates. All isolates tested were susceptible to ceftriaxone; two isolates were less susceptible to ciprofloxacin; and one isolate was resistant to rifampicin.

Management of meningococcal outbreaks: are we using the same language? Comparison of the public health policies between high-income countries with low incidence of meningococcal disease

BACKGROUND

Invasive meningococcal disease (IMD) in high-income countries usually occurs sporadically with low incidence and occasionally as small clusters or outbreaks. The WHO guidelines (GLs) for IMD outbreak applies only to African countries with high endemic incidence. Several high-income countries developed their own GLs on IMD outbreak, and we compare their terminology, classification, definitions, and public health interventions.

METHODS

National IMD outbreak GLs of the European Union and the Organisation for Economic Co-operation and Development member states were compared. Due to linguistic barriers, 17 out of forty-one countries were selected, and the GLs on the websites of the national health authorities were independently screened by two researchers.

RESULTS

National GLs on IMD outbreak were available for 12 countries. All GLs classify IMD outbreak into organization and community based using different terminology (cluster, epidemic, etc.). Two GLs introduce also a third condition of hyperendemic. Definitions, thresholds, and countermeasures vary among countries.

CONCLUSIONS

Different definitions of organization and community-based outbreaks and countermeasures are expected because of uncertainties about their effectiveness, and differences between countries in health-care systems and public health policy approaches. Nevertheless, variations in terminology, definitions and countermeasures are confusing and reflect the need for an international standardization.

Meningococcal Quadrivalent Tetanus Toxoid Conjugate Vaccine (MenACWY-TT; Nimenrix®): A Review

MenACWY-TT (Nimenrix^®) is a quadrivalent meningococcal tetanus toxoid conjugate vaccine licensed in Europe for active immunisation of individuals aged ≥ 6 weeks against invasive disease caused by Neisseria meningitidis capsular groups A, C, W and Y. MenACWY-TT is the first quadrivalent conjugate vaccine to be approved in Europe for use in infants as young as 6 weeks of age. Numerous phase II-IIIb clinical studies showed that intramuscular MenACWY-TT administered as primary or booster vaccination was highly immunogenic for all four vaccine capsular groups and had an acceptable reactogenicity profile in individuals aged 6 weeks to ≥ 56 years. MenACWY-TT is as immunogenic and safe as other previously licensed monovalent capsular group C or quadrivalent capsular groups A, C, W and Y meningococcal vaccines and can be coadministered with other routine vaccines without adversely affecting the immunogenicity or safety profiles of either vaccine. Current data indicate that primary and booster vaccination with MenACWY-TT is a valuable and safe option for broadening meningococcal protection against four capsular groups across a broad age range, starting as early as 6 weeks of age.

Meningococcal disease in the Middle East and Africa: Findings and updates from the Global Meningococcal Initiative

The Global Meningococcal Initiative (GMI) has recently considered current issues in Middle Eastern and African countries, and produced two recommendations: (i) that vaccination of attendees should be considered for some types of mass-gathering events, as some countries mandate for the Hajj, and (ii) vaccination of people with human immunodeficiency virus should be used routinely, because of increased meningococcal disease (MD) risk. Differences exist between Middle Eastern and African countries regarding case and syndrome definitions, surveillance, and epidemiologic data gaps. Sentinel surveillance provides an overview of trends and prevalence of different capsular groups supporting vaccine selection and planning, whereas cost-effectiveness decisions require comprehensive disease burden data, ideally counting every case. Surveillance data showed importance of serogroup B MD in North Africa and serogroup W expansion in Turkey and South Africa. Success of MenAfriVac^® in the African "meningitis belt" was reviewed; the GMI believes similar benefits may follow development of a low-cost meningococcal pentavalent vaccine, currently in phase 1 clinical trial, by 2022. The importance of carriage and herd protection for controlling invasive MD and the importance of advocacy and awareness campaigns were also highlighted.

Control of invasive meningococcal disease: is it achievable?

Neisseria meningitidis still leads to deaths and severe disability in children, adolescents and adults. Six different capsular groups of N. meningitidis cause invasive meningococcal disease in the form of meningitis and septicaemia in humans. Although conjugate meningococcal vaccines have been developed to provide protection against four of the capsular groups causing most diseases in humans, vaccines against capsular group B, which causes 85% of cases in Australia and the United Kingdom, have only recently been developed. A capsular group B meningococcal vaccine - 4CMenB (Bexsero) - has recently been licensed in the European Union, Canada and Australia. In Australia, a submission for inclusion of 4CMenB in the funded national immunization programme has recently been rejected. The vaccine will now be introduced into the national immunization programme in the United Kingdom following negotiation of a cost-effective price. With the current low incidence of invasive meningococcal disease in many regions, cost-effectiveness of a new capsular group B meningococcal vaccine is borderline in both the United Kingdom and Australia. Cost-effectiveness of an infant programme is determined largely by the direct protection of those vaccinated and is driven by the higher rate of disease in this age group. However, for an adolescent programme to be cost-effective, it must provide both long-term protection against both disease and carriage. The potential of vaccination to reduce the rate of severe invasive disease is a real possibility. A dual approach using both an infant and adolescent immunization programme to provide direct protection to those age groups at highest risk of meningococcal disease and to optimize the potential herd immunity effects is likely to be the most effective means of reducing invasive meningococcal disease. This commentary aims to describe the known disease burden and consequences of meningococcal disease, and the development and potential effectiveness of new capsular group B meningococcal vaccines.

A High-Throughput Size Exclusion Chromatography Method to Determine the Molecular Size Distribution of Meningococcal Polysaccharide Vaccine

Molecular size distribution of meningococcal polysaccharide vaccine is a readily identifiable parameter that directly correlates with the immunogenicity. In this paper, we report a size exclusion chromatography method to determine the molecular size distribution and distribution coefficient value of meningococcal polysaccharide serogroups A, C, W, and Y in meningococcal polysaccharide (ACWY) vaccines. The analyses were performed on a XK16/70 column packed with sepharose CL-4B with six different batches of Ingovax® ACWY, a meningococcal polysaccharide vaccine produced by Incepta Vaccine Ltd., Bangladesh. A quantitative rocket immunoelectrophoresis assay was employed to determine the polysaccharide contents of each serogroup. The calculated distribution coefficient values of serogroups A, C, W, and Y were found to be 0.26 ± 0.16, 0.21 ± 0.11, 0.21 ± 0.11, and 0.14 ± 0.12, respectively, and met the requirements of British Pharmacopeia. The method was proved to be robust for determining the distribution coefficient values which is an obligatory requirement for vaccine lot release.

Meningococcal serogroup Y disease in Europe: Continuation of high importance in some European regions in 2013

Neisseria meningitidis or meningococcus is divided into 12 distinct serogroups of which A, B, C, W, X, and Y are medically most important and cause health problems in different parts of the world. The epidemiology of N. meningitidis is unpredictable over time and across geographic regions. Globally, serogroup A has been prevalent in the African "meningitis belt" whereas serogroup B and C have predominated in Europe. In a paper published earlier in this journal (1) , an increase in serogroup Y invasive meningococcal disease (IMD) in some European countries was reported based on the epidemiological data for 2010, 2011 and 2012. Here, we report additional data from 30 European countries indicating that high or increased serogroup Y disease levels have continued in 2013 in certain regions of Europe. In the Western and Central Europe, there were no major changes in the proportion of serogroup Y IMD cases in 2013 compared to 2012. In the Scandinavian countries, proportion of serogroup Y disease remained high, ranging from 26% to 51% in 2013. This was in contrast to Baltic, Eastern and most Southern European countries, where the proportion of serogroup Y IMD was low similarly to previous years. For the last 2 decades, the mean age of patients affected by serogroup Y was 41 y for 7 countries from which data was available and 50% of cases were in patients aged 45 to 88 y. The age distribution of serogroup Y was bimodal and did not change significantly despite the increase of the total number and the proportion of serogroup Y IMD in some European regions.

Persistent occurrence of serogroup Y/sequence type (ST)-23 complex invasive meningococcal disease among patients aged five to 14 years, Italy, 2007 to 2013

In Italy, the incidence of invasive meningococcal disease (IMD) has remained stable since 2007 (around 0.3 cases/100,000 inhabitants). However, as reported for other European countries, an increase of serogroup Y Neisseria meningitidis has been observed. In this study we report IMD cases from 2007 to 2013 in Italy and investigate the clinical and epidemiological features of cases affected by serogroup Y. Molecular characteristics of serogroup Y strains are also described. During the study period, the proportion of IMD cases due to serogroup Y increased, ranging from 2% in 2007 to 17% in 2013 (odds ratio (OR): 8.8), whereby the five to 14 years age group was mostly affected (p < 0.001). Overall 81 serogroup Y IMD cases were identified, with a median age of 18 years, ranging from three months to 84 years. Of the 81 respective patient samples, 56 were further subject to molecular typing. The sequence type (ST)-23 complex (clonal complex (cc)23) was predominant among serogroup Y meningococci (54/56 samples), and included nine different STs. Presumably, ST-23 was the founding genotype, with all the other STs presenting as single-locus variants. All cc23 isolates analysed harboured mutations in the lpxL1 gene; however, no associations among lpxL1 mutations, ST and age group were identified. Overall, these findings generate scientific evidence for the use of the quadrivalent meningococcal conjugate vaccine in the five to 14 years age group.

Immunogenicity, Safety and Antibody Persistence of a Booster Dose of Quadrivalent Meningococcal ACWY-tetanus Toxoid Conjugate Vaccine Compared with Monovalent Meningococcal Serogroup C Vaccine Administered Four Years After Primary Vaccination Using the Same Vaccines

BACKGROUND

We evaluated safety, immunogenicity and antibody persistence of meningococcal serogroups A, C, W and Y tetanus toxoid conjugate vaccine (MenACWY-TT) booster vaccination 4 years after priming of toddlers.

METHODS

This phase III, open-label, controlled study in Finland (NCT00955682) enrolled children previously randomized (3:1) at 12-23 months (NCT00474266) to receive 1 dose of MenACWY-TT or MenC conjugate vaccine (MenC-CRM197). Serum bactericidal antibody titers using rabbit (rSBA, cut-off 1:8) and human complement (hSBA, cut-off 1:8) were assessed at year 3 and 4 after priming and 1 month and 1 year after administration of a booster dose of the same vaccine given for primary vaccination. Reactogenicity and safety were assessed, and vaccination-related serious adverse events were recorded from the time of primary vaccination.

RESULTS

Before booster (year 4), 74.1%, 40.4%, 49.3% and 58.2% of MenACWY-TT-recipients retained rSBA titers ≥1:8 for serogroups A, C, W and Y, respectively; 28.8%, 73.2%, 80.6% and 65.4% retained hSBA ≥1:8. Percentages for the MenC-CRM group were 35.6% (rSBA-MenC) and 46.9% (hSBA-MenC). After MenACWY-TT booster, ≥99.5% had rSBA ≥1:8 and hSBA ≥1:8 for each serogroup. After MenC-CRM197 booster, all children had rSBA-MenC ≥1:8 and hSBA-MenC ≥1:8. At year 5, percentages above the cut-off were ≥97.4% (rSBA) and ≥95.5% (hSBA) in MenACWY-TT-vaccinees for each serogroup. The MenACWY-TT booster dose had a clinically acceptable safety profile. No vaccine-related serious adverse events were reported.

CONCLUSION

There was evidence of antibody persistence 4 years after toddlers were primed with MenACWY-TT. Booster vaccination induced robust immune responses for all serogroups with an acceptable safety profile.

Oropharyngeal Carriage of Meningococcus in Portugal by Group and Clonal Complex 6 Years After Adolescent Vaccine Campaign

Portugal introduced (2+1) conjugate Meningococcal group C vaccine in 2006 with high coverage catch up to 18 years and has given only 1 dose at 1 year since 2012. Among 601 student oropharyngeal swabs, meningococcal carriage rate was 13.3% (A-0%, B-5.3%, C-0.3%, W-0.2%, X-0.2% and Y-1.7%). C and W strains were of potentially disease-causing clonal complexes (cc) but not the hyperinvasive cc11.

Genomic epidemiology of age-associated meningococcal lineages in national surveillance: an observational cohort study

Background

Invasive meningococcal disease (IMD) is a worldwide health issue that is potentially preventable with vaccination. In view of its sporadic nature and the high diversity of Neisseria meningitidis, epidemiological surveillance incorporating detailed isolate characterisation is crucial for effective control and understanding the evolving epidemiology of IMD. The Meningitis Research Foundation Meningococcus Genome Library (MRF-MGL) exploits whole-genome sequencing (WGS) for this purpose and presents data on a comprehensive and coherent IMD isolate collection from England and Wales via the internet. We assessed the contribution of these data to investigating IMD epidemiology.

Methods

WGS data were obtained for all 899 IMD isolates available for England and Wales in epidemiological years 2010–11 and 2011–12. The data had been annotated at 1720 loci, analysed, and disseminated online. Information was also available on meningococcal population structure and vaccine (Bexsero, GlaxoSmithKline, Brentford, Middlesex, UK) antigen variants, which enabled the investigation of IMD-associated genotypes over time and by patients' age groups. Population genomic analyses were done with a hierarchical gene-by-gene approach.

Findings

The methods used by MRF-MGL efficiently characterised IMD isolates and information was provided in plain language. At least 20 meningococcal lineages were identified, three of which (hyperinvasive clonal complexes 41/44 [lineage 3], 269 [lineage 2], and 23 [lineage 23]) were responsible for 528 (59%) of IMD isolates. Lineages were highly diverse and showed evidence of extensive recombination. Specific lineages were associated with IMD in particular age groups, with notable diversity in the youngest and oldest individuals. The increased incidence of IMD from 1984 to 2010 in England and Wales was due to successive and concurrent epidemics of different lineages. Genetically, 74% of isolates were characterised as encoding group B capsules: 16% group Y, 6% group W, and 3% group C. Exact peptide matches for individual Bexsero vaccine antigens were present in up to 26% of isolates.

Interpretation

The MRF-MGL represents an effective, broadly applicable model for the storage, analysis, and dissemination of WGS data that can facilitate real-time genomic pathogen surveillance. The data revealed information crucial to effective deployment and assessment of vaccines against N meningitidis.

Funding

Meningitis Research Foundation, Wellcome Trust, Public Health England, European Union.

Need for Optimisation of Immunisation Strategies Targeting Invasive Meningococcal Disease in the Netherlands

Invasive meningococcal disease (IMD) is a severe bacterial infectious disease with high mortality and morbidity rates worldwide. In recent years, industrialised countries have implemented vaccines targeting IMD in their National Immunisation Programmes (NIPs). In 2002, the Netherlands successfully implemented a single dose of meningococcal serogroup C conjugate vaccine at the age of 14 months and performed a single catch-up for children ≤18 years of age. Since then the disease disappeared in vaccinated individuals. Furthermore, herd protection was induced, leading to a significant IMD reduction in non-vaccinated individuals. However, previous studies revealed that the current programmatic immunisation strategy was insufficient to protect the population in the foreseeable future. In addition, vaccines that provide protection against additional serogroups are now available. This paper describes to what extent the current strategy to prevent IMD in the Netherlands is still sufficient, taking into account the burden of disease and the latest scientific knowledge related to IMD and its prevention. In particular, primary MenC immunisation seems not to provide long-term protection, indicating a risk for possible recurrence of the disease. This can be combatted by implementing a MenC or MenACWY adolescent booster vaccine. Additional health benefits can be achieved by replacing the primary MenC by a MenACWY vaccine. By implementation of a recently licensed MenB vaccine for infants in the NIP, the greatest burden of disease would be targeted. This paper shows that optimisation of the immunisation strategy targeting IMD in the Netherlands should be considered and contributes to create awareness concerning prevention optimisation in other countries.

Genome-Based Characterization of Emergent Invasive Neisseria meningitidis Serogroup Y Isolates in Sweden from 1995 to 2012

Invasive meningococcal disease (IMD) caused by Neisseria meningitidis serogroup Y has increased in Europe, especially in Scandinavia. In Sweden, serogroup Y is now the dominating serogroup, and in 2012, the serogroup Y disease incidence was 0.46/100,000 population. We previously showed that a strain type belonging to sequence type 23 was responsible for the increased prevalence of this serogroup in Sweden. The objective of this study was to investigate the serogroup Y emergence by whole-genome sequencing and compare the meningococcal population structure of Swedish invasive serogroup Y strains to those of other countries with different IMD incidence. Whole-genome sequencing was performed on invasive serogroup Y isolates from 1995 to 2012 in Sweden (n = 186). These isolates were compared to a collection of serogroup Y isolates from England, Wales, and Northern Ireland from 2010 to 2012 (n = 143), which had relatively low serogroup Y incidence, and two isolates obtained in 1999 in the United States, where serogroup Y remains one of the major causes of IMD. The meningococcal population structures were similar in the investigated regions; however, different strain types were prevalent in each geographic region. A number of genes known or hypothesized to have an impact on meningococcal virulence were shown to be associated with different strain types and subtypes. The reasons for the IMD increase are multifactorial and are influenced by increased virulence, host adaptive immunity, and transmission. Future genome-wide association studies are needed to reveal additional genes associated with serogroup Y meningococcal disease, and this work would benefit from a complete serogroup Y meningococcal reference genome.

Meningococcal carriage in adolescents in the United Kingdom to inform timing of an adolescent vaccination strategy

OBJECTIVES

Recent development of serogroup B meningococcal (MenB) vaccines highlights the importance of pharyngeal carriage data, particularly in adolescents and young adults, to inform implementation strategies. We describe current UK carriage prevalence in this high risk population and compare methods of carriage detection.

METHODS

In this multisite study, pharyngeal swabs were collected on 3-4 occasions over 6-12 months, from 1040 school and university students, aged 10-25 years. Meningococcal carriage was detected by standard culture combined with seroagglutination or PCR of cultured isolates, or by direct PCR from swab. The factor H binding protein (fHBP) variants present in meningococcal isolates were determined.

RESULTS

Meningococcal serogroups B and Y were most common, with carriage up to 6.5% and 5.5% respectively, increasing throughout adolescence. Identification by seroagglutination was often unreliable, and the sensitivity of direct PCR detection was 66% compared to culture combined with PCR. Of MenB isolates, 89.1% had subfamily A variants of fHBP. The acquisition rate of MenB carriage was estimated at 2.8 per 1000 person-months.

CONCLUSIONS

If vaccination is to precede the adolescent rise in MenB carriage, these data suggest it should take place in early adolescence. Studies assessing vaccine impact should use molecular methods to detect carriage.

Changes in the Population Structure of Invasive Neisseria meningitidis in the United States After Quadrivalent Meningococcal Conjugate Vaccine Licensure

BACKGROUND

Meningococcal conjugate vaccines against serogroups A, C, W, and Y (MenACWY) are recommended for routine use in adolescents aged 11-18 years. The impact of these vaccines on the meningococcal population structure in the United States have yet to be evaluated.

METHODS

Meningococcal isolates recovered during 2006-2010 (ie, after introduction of MenACWY) collected through Active Bacterial Core surveillance (ABCs) were characterized; serogroup distribution and molecular features of these isolates were compared to previously published data on ABCs isolates recovered from 2000 to 2005 (ie, before introduction of MenACWY). P values were generated using χ(2) statistics and exact methods.

RESULTS

There was a significant change (P < .05) in serogroup distribution among all age groups between the 2 periods. A small proportion of isolates showed evidence of capsular switching in both periods. Between the 2 periods, significant changes were observed in the distribution of porin A, ferric enterobactin transport, and strain genotypes among vaccine and nonvaccine serogroups.

CONCLUSIONS

The population structure of US meningococcal isolates is dynamic; some changes occurred over time, but the basic structure remained. Vaccine-induced serogroup replacement was not observed, although a small proportion of isolates had undergone capsule switching, possibly driven by non-vaccine-mediated selection. Changes in the distribution of molecular features are likely due to horizontal gene transfer and changes in serogroup distribution.

Prevention of rare diseases: how revolutionary techniques can help vulnerable individuals-the example of serogroup B meningococcal infection

In countries with established programmes for vaccination of infants, toddlers and adolescents with meningococcal conjugate vaccines, serogroup B invasive meningococcal disease remains the major cause of septicaemia and meningitis in the paediatric and adolescent age groups. Novartis has developed a serogroup B meningococcal vaccine, 4CMenB, to meet this need. We reviewed all 4CMenB studies. The studies found 4CMenB to be highly immunogenic when administered in all schedules, with protective antibody levels (serum bactericidal antibody titres ≥4 or ≥5 with human complement, hSBA) against serogroup B strains expressing vaccine antigens in >95% of vaccinated cohorts. When antibody levels waned, all tested groups demonstrated booster responses. Although possibly an underestimation, the Meningococcal Antigen Typing System (MATS) technique predicts that global coverage of 4CMenB against all serogroup B strains is in the range 66% (Canada) to 91% (USA). The vaccine was found to be generally well tolerated, although local and systemic reactions, notably fever in infants, typical of many vaccines, were increased following concomitant administration of 4CMenB with routine vaccines. When tested, prophylactic paracetamol significantly decreased the frequency and severity of reactions in infants, with no clinically significant impact on immunogenicity of 4CMenB or concomitant routine vaccines. The vaccine is approved for use in the following age groups in the European Union (2 months+), Canada (2 months through 17 years), Australia (2 months+) and Chile (2 months+), following clinical evaluation in 4843 infants and toddlers, and 1712 adolescents and adults, in schedules including a three-dose (2, 3, 4 or 2, 4, 6 months) and a two-dose (6-11 months) infant series with a booster in the second year of life, a two-dose series in toddlers (12-23 months) and children (2-10 years) given 2 months apart (with a booster at least in the EU), and a two-dose series in adolescents (11-17 years) given 1-6 months apart. 4CMenB presents a solution to the unmet medical need of offering protection against serogroup B invasive meningococcal disease in all age groups above 2 months.

Glycoconjugate vaccines: an update

INTRODUCTION

Globally, the three main pathogens causing serious infections are Haemophilus influenzae type b, Streptococcus pneumoniae and Neisseria meningitidis. Over the last 5 years, new vaccines protecting against these bacteria have been developed and introduced in various countries.

AREAS COVERED

This review describes the recently licensed glycoconjugates being used to protect against these encapsulated bacteria. Immunogenicity and safety data that led to licensure or licensure expansion of these glycoconjugates are discussed in addition to the resultant impact on the disease burden.

EXPERT OPINION

The maintenance of robust immunisation programmes with high uptake rates is important in maintaining low rates of disease. Epidemiological surveillance systems are essential in monitoring any changes in infectious disease trends and in identifying emerging infections such as from non-typeable H. influenzae, pneumococcal serotype replacement disease and changes in the epidemiology of meningococcal serogroups. This is important to guide future vaccine development. Accessibility of these glycoconjugate vaccines in resource poor regions, which bear the highest disease burden from these pathogens, remains challenging largely due to high vaccine pricing. Recent aids from public and private funding, tiered vaccine pricing and the transfer of vaccine technology have helped in introducing these vaccines where they are most needed.

Surveillance of invasive Neisseria meningitidis with a serogroup Y update, Sweden 2010 to 2012

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Implications of differential age distribution of disease-associated meningococcal lineages for vaccine development

New vaccines targeting meningococci expressing serogroup B polysaccharide have been developed, with some being licensed in Europe. Coverage depends on the distribution of disease-associated genotypes, which may vary by age. It is well established that a small number of hyperinvasive lineages account for most disease, and these lineages are associated with particular antigens, including vaccine candidates. A collection of 4,048 representative meningococcal disease isolates from 18 European countries, collected over a 3-year period, were characterized by multilocus sequence typing (MLST). Age data were available for 3,147 isolates. The proportions of hyperinvasive lineages, identified as particular clonal complexes (ccs) by MLST, differed among age groups. Subjects <1 year of age experienced lower risk of sequence type 11 (ST-11) cc, ST-32 cc, and ST-269 cc disease and higher risk of disease due to unassigned STs, 1- to 4-year-olds experienced lower risk of ST-11 cc and ST-32 cc disease, 5- to 14-year-olds were less likely to experience ST-11 cc and ST-269 cc disease, and ≥25-year-olds were more likely to experience disease due to less common ccs and unassigned STs. Younger and older subjects were vulnerable to a more diverse set of genotypes, indicating the more clonal nature of genotypes affecting adolescents and young adults. Knowledge of temporal and spatial diversity and the dynamics of meningococcal populations is essential for disease control by vaccines, as coverage is lineage specific. The nonrandom age distribution of hyperinvasive lineages has consequences for the design and implementation of vaccines, as different variants, or perhaps targets, may be required for different age groups.

Meningococcal serogroup Y emergence in Europe: high importance in some European regions in 2012

Neisseria meningitidis is differentiated into 12 distinct serogroups, of which A, B, C, W, X, and Y are medically most important and represent an important health problem in different parts of the world. The epidemiology of N. meningitidis is unpredictable over time and across geographic regions. Recent epidemiological surveillance has indicated an increase of serogroup Y invasive meningococcal disease in some parts of Europe as shown in the epidemiological data for 2010 and 2011 from various European countries previously published in this journal. (1)(,) (2) Here, data from 33 European countries is reported indicating that the emergence of serogroup Y continued in 2012 in various regions of Europe, especially in Scandinavia, while in Eastern and South-Eastern Europe the importance of serogroup Y remained low.

A decade of invasive meningococcal disease surveillance in Poland

Background

Neisseria meningitidis is a leading etiologic agent of severe invasive disease. The objective of the study was to characterise invasive meningococcal disease (IMD) epidemiology in Poland during the last decade, based on laboratory confirmed cases.

Methods

The study encompassed all invasive meningococci collected between 2002 and 2011 in the National Reference Centre for Bacterial Meningitis. The isolates were re-identified and characterised by susceptibility testing, MLST analysis, porA and fetA sequencing. A PCR technique was used for meningococcal identification directly from clinical materials.

Results

In the period studied, 1936 cases of IMD were confirmed, including 75.6% identified by culture. Seven IMD outbreaks, affecting mostly adolescents, were reported; all were caused by serogroup C meningococci of ST-11. The highest incidence was observed among children under one year of age (15.71/100,000 in 2011). The general case fatality rate in the years 2010–2011 was 10.0%. Meningococci of serogroup B, C, Y and W-135 were responsible for 48.8%, 36.6%, 1.2% and 1.2% of cases, respectively. All isolates were susceptible to third generation cephalosporins, chloramphenicol, ciprofloxacin, and 84.2% were susceptible to penicillin. MLST analysis (2009–2011) revealed that among serogroup B isolates the most represented were clonal complexes (CC) ST-32CC, ST-18CC, ST-41/44CC, ST-213CC and ST-269CC, and among serogroup C: ST-103CC, ST-41/44CC and ST-11CC.

Conclusions

The detection of IMD in Poland has changed over time, but observed increase in the incidence of the disease was mostly attributed to changes in the surveillance system including an expanded case definition and inclusion of data from non-culture diagnostics.