Genomic Surveillance of Invasive Meningococcal Disease During a National MenW Outbreak in Australia, 2017-2018

Background

In Australia, invasive meningococcal disease (IMD) incidence rapidly increased between 2014 and 2017 due to rising serogroup W (MenW) and MenY infections. We aimed to better understand the genetic diversity of IMD during 2017 and 2018 using whole genome sequencing data.

Methods

Whole genome sequencing data from 440 Australian IMD isolates collected during 2017 and 2018 and 1737 international MenW:CC11 isolates collected in Europe, Africa, Asia, North America, and South America between 1974 and 2020 were used in phylogenetic analyses; genetic relatedness was determined from single-nucleotide polymorphisms.

Results

Australian isolates were as follows: 181 MenW (41%), 144 MenB (33%), 88 MenY (20%), 16 MenC (4%), 1 MenW/Y (0.2%), and 10 nongenogroupable (2%). Eighteen clonal complexes (CCs) were identified, and 3 (CC11, CC23, CC41/44) accounted for 78% of isolates (343/440). These CCs were associated with specific serogroups: CC11 (n = 199) predominated among MenW (n = 181) and MenC (n = 15), CC23 (n = 80) among MenY (n = 78), and CC41/44 (n = 64) among MenB (n = 64). MenB isolates were highly diverse, MenY were intermediately diverse, and MenW and MenC isolates demonstrated the least genetic diversity. Thirty serogroup and CC-specific genomic clusters were identified. International CC11 comparison revealed diversification of MenW in Australia.

Conclusions

Whole genome sequencing comprehensively characterized Australian IMD isolates, indexed their genetic variability, provided increased within-CC resolution, and elucidated the evolution of CC11 in Australia.

Molecular characterization of invasive Neisseria meningitidis isolates collected in Lithuania (2009-2019) and estimation of serogroup B meningococcal vaccine 4CMenB and MenB-Fhbp coverage

Neisseria meningitidis causes invasive meningococcal disease (IMD), which is associated with significant mortality and long-term consequences, especially among young children. The incidence of IMD in Lithuania was among the highest in European Union/European Economic Area countries during the past two decades; however, the characterization of meningococcal isolates by molecular typing methods has not yet been performed. In this study, we characterized invasive meningococcal isolates (n=294) recovered in Lithuania from 2009 to 2019 by multilocus sequence typing (MLST) and typing of antigens FetA and PorA. The more recent (2017-2019) serogroup B isolates (n=60) were genotyped by analyzing vaccine-related antigens to evaluate their coverage by four-component (4CMenB) and two-component (MenB-Fhbp) vaccines using the genetic Meningococcal Antigen Typing System (gMATS) and Meningococcal Deduced Vaccine Antigen Reactivity (MenDeVAR) Index methods, respectively. The vast majority (90.5%) of isolates belonged to serogroup B. MLST revealed a predominance of clonal complex 32 (74.02%). Serogroup B strain P1.19,15: F4-28: ST-34 (cc32) accounted for 64.1% of IMD isolates. The overall level of strain coverage by the 4MenB vaccine was 94.8% (CI 85.9-98.2%). Most serogroup B isolates (87.9%) were covered by a single vaccine antigen, most commonly Fhbp peptide variant 1 (84.5% of isolates). The Fhbp peptides included in the MenB-Fhbp vaccine were not detected among the analyzed invasive isolates; however, the identified predominant variant 1 was considered cross-reactive. In total, 88.1% (CI 77.5-94.1) of isolates were predicted to be covered by the MenB-Fhbp vaccine. In conclusion, both serogroup B vaccines demonstrate potential to protect against IMD in Lithuania.

Public Health Impact and Cost-Effectiveness Analysis of Routine Infant 4CMenB Vaccination in Germany to Prevent Serogroup B Invasive Meningococcal Disease

Introduction

Invasive meningococcal disease (IMD) is an uncommon, severe, life-threatening disease primarily affecting infants, with potential lifelong sequelae. Neisseria meningitidis (Nm) serogroup B (MenB) causes most IMD cases in Germany, many of which can be prevented with four-component MenB (4CMenB) vaccination. The potential public health and economic impact of introducing routine 4CMenB infant vaccination in Germany was assessed.

Methods

A dynamic transmission-based cost-effectiveness model adapted for Germany assessed the impact of infant 4CMenB universal mass vaccination (UMV) versus no vaccination. The model included the latest real-world evidence on vaccine effectiveness, the comprehensive burden of disease on patients (sequelae) and their family (quality of life impact), comprehensive German IMD costs, and vaccination uptake assumptions.

Results

The largest public health impact was predicted in children: a rapid decline, 5 years after UMV implementation, of 39.9% (34.7%) for MenB (all IMD) cases aged 0–4 years and 42.4% (36.8%) in infants. Over lifetime (100-year time horizon), 4CMenB could prevent 3154 MenB (3303 all IMD) cases, 291 MenB (304 all IMD) deaths and 1370 MenB (1435 all IMD) long-term sequelae. 4CMenB saved 25,878 quality-adjusted life-years (QALYs), at a cost of €188,762 per QALY gained in the base case (societal perspective including lost productivity). Scenarios including potential Nm carriage protection (enabling herd protection) or societal preferences for the prevention of severe diseases led to more cost-effective results, while a scenario excluding IMD impact beyond the patient with increased discounting of vaccination health benefits produced less cost-effective results.

Conclusions

MenB IMD is a vaccine-preventable disease. This analysis for Germany can inform decision-makers on the potential impact of introducing infant 4CMenB UMV. The program is predicted to rapidly produce health benefits (reduction in child cases, deaths and sequelae) at a cost per QALY to society of around €190,000 (base case), decreasing to around €78,000 when considering societal preferences and IMD underreporting.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40121-021-00573-w.

Invasive meningococcal disease (IMD) is an uncommon but severe infection, usually presenting as meningitis and/or sepsis, caused by the bacteria Neisseria meningitidis. Most cases occur in infants, young children and adolescents. Patients who survive the disease can develop lifelong sequelae, such as physical, neurological and psychological/behavioural problems that impact their quality of life and that of their family/caregivers. This disease can be prevented by vaccination. The use of the four-component meningococcal serogroup B vaccine (4CMenB) in countries like Germany can prevent the most common form of this disease, IMD caused by serogroup B. This study assessed the public health and economic impact of infant vaccination in Germany with 4CMenB. For this, the authors used an economic model that measured the lifetime impact of the disease on patients but also on their families. The model predicted that after 5 years of vaccination, the number of cases and deaths in infants and young children aged 0–4 years would rapidly decrease by almost 40%. Over a long-term horizon of 100 years, this number was predicted to remain stable. Due to the reduced number of cases, vaccination would also result in fewer deaths and patients with sequelae, as well as cost savings for the healthcare system and society due to the reduced loss of productivity. In conclusion, in Germany, IMD caused by serogroup B is preventable through vaccination, and the 4CMenB vaccine in German infants is predicted to rapidly reduce the disease burden, save lives and prevent healthcare costs.

Four-component Meningococcal Serogroup B Vaccine Induces Antibodies With Bactericidal Activity Against Diverse Outbreak Strains in Adolescents

BACKGROUND

Neisseria meningitidis serogroup B (MenB) causes most meningitis outbreaks worldwide. We evaluated the ability of the 4-component MenB vaccine (4CMenB) to induce bactericidal activity against outbreak strains in adolescents.

METHODS

Individual sera from 20 United States and 23 Chilean adolescents who received 2 doses of 4CMenB 2 months apart were assayed at prevaccination and 1 month after second dose using a human complement serum bactericidal antibody assay (hSBA) against a full or subset strain panel consisting of 14 MenB outbreak strains and 1 MenW hyperendemic strain collected between 2001 and 2017 in the United States, United Kingdom, and France. Bactericidal activity was determined as the percentage of adolescents with hSBA titer ≥1:4 or ≥1:8.

RESULTS

One month after the second 4CMenB dose, antibodies from 65% to 100% of the US adolescents were able to kill 12 of 15 strains at 1:4 dilution. The remaining 3 strains were killed by 45%, 25%, and 15% of US adolescent sera. Similar percentages exhibited hSBA titers of ≥1:8. Across a subset of 4 strains, point estimates for the percentages of Chilean and US adolescents with hSBA titers of ≥1:4 after the second 4CMenB dose were similar (100% for strain M27703, 74% vs. 80% for M26312, 52% vs. 45% for M08 0240745), except for strain M39090 (91% vs. 65%).

CONCLUSIONS

This study was the first to evaluate bactericidal activity elicited by a MenB vaccine against 15 outbreak strains. Two doses of 4CMenB elicited bactericidal activity against MenB outbreak strains and a hyperendemic MenW strain.

Cost-Effectiveness of 4CMenB Infant Vaccination in England: A Comprehensive Valuation Considering the Broad Impact of Serogroup B Invasive Meningococcal Disease

OBJECTIVES

This cost-effectiveness analysis (CEA) of 4CMenB infant vaccination in England comprehensively considers the broad burden of serogroup B invasive meningococcal disease (MenB IMD), which has not been considered, or was only partially considered in previous CEAs.

METHODS

A review of previous MenB vaccination CEAs was conducted to identify aspects considered in the evaluation of costs and health outcomes of the disease burden of MenB IMD. To inform the model structure and comprehensive analysis, the aspects were grouped into 5 categories. A stepwise analysis was conducted to analyze the impact of each category, and the more comprehensive consideration of disease burden, on the incremental cost-effectiveness ratio (ICER).

RESULTS

MenB IMD incidence decreased by 46.0% in infants and children 0-4 years old within 5 years after introduction of the program. Stepwise inclusion of the 5 disease burden categories to a conventional narrow CEA setting reduced the ICER from £360 595 to £18 645-that is, considering the impact of all 5 categories, 4CMenB infant vaccination is cost-effective at a threshold of £20 000 per QALY gained.

CONCLUSIONS

When considering comprehensively the MenB IMD burden, 4CMenB infant vaccination can be cost-effective, a finding contrary to previous CEAs. This analysis allows policy decision-makers globally to infer the impact of current disease burden considerations on the cost-effectiveness and the comprehensive assessment necessary for MenB IMD. Although this comprehensive CEA can help inform decision making today, it may be limited in capturing the full disease burden and complex interactions of health and economics of MenB IMD.

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.

Molecular characterization of Neisseria meningitidis isolates recovered from patients with invasive meningococcal disease in Colombia from 2013 to 2016

BACKGROUND

Neisseria meningitidis is a significant cause of morbidity and mortality worldwide. Meningococcal isolates have a highly dynamic population structure and can be phenotypically and genetically differentiated into serogroups and clonal complexes. The aim of this study was to describe the phenotypic and genotypic characteristics of invasive isolates recovered in Colombia from 2013 to 2016.

METHODOLOGY

A total of 193 invasive isolates were analyzed. Phenotypic and genotypic characteristics were determined by serotyping, antimicrobial susceptibility testing, pulsed-field gel electrophoresis (PFGE) and whole-genome sequencing.

RESULTS

Based on the results, meningococcal serogroups C, B and Y were responsible for 47.9%, 41.7%, and 9.4% of cases, respectively, and the distribution of serogroups B and C changed over time. Fifteen clonal groups and 14 clonal complexes (cc) were identified by PFGE and genome sequencing. The main clonal group included serogroup B isolates with sequence type (ST)-9493 and its four single-locus variants, which has only been identified in Colombian isolates. The clonal population structure demonstrates that the isolates in this study mainly belong to four clonal complexes: ST-11 cc, ST-32 cc, ST-35 cc and ST-41/44 cc. Thirty-eight penA alleles were identified, but no correlation between MICs and specific sequences was observed.

CONCLUSION

This study shows that most meningococcal isolates recovered from patients with invasive meningococcal disease in Colombia are strains associated with distinct globally disseminated hyperinvasive clones.

Serum Bactericidal Antibody Responses of Students Immunized With a Meningococcal Serogroup B Vaccine in Response to an Outbreak on a University Campus

Background

MenB-4C is a recently licensed meningococcal serogroup B vaccine. For vaccine licensure, short-term efficacy was inferred from serum bactericidal antibody (SBA) titers against 3 antigen-specific indicator strains, which are not necessarily representative of US disease-causing strains.

Methods

A total of 4923 students were immunized with MenB-4C in response to an outbreak at a university. Serum samples were obtained at 1.5-2 months from 106 students who received the recommended 2 doses and 52 unvaccinated students. Follow-up serum samples were obtained at 7 months from 42 vaccinated and 24 unvaccinated participants. SBA was measured against strains from 4 university outbreaks.

Results

At 1.5-2 months, the proportion of immunized students with protective titers ≥1:4 against an isolate from the campus outbreak was 93% (95% confidence interval [CI], 87%-97%) vs 37% (95% CI, 24%-51%) in unvaccinated students. The proportion with protective titers against strains from 3 other university outbreaks was 73% (95% CI, 62%-82%) vs 26% (95% CI, 14%-41%) in unvaccinated; 71% (95% CI, 61%-79%) vs 19% (95% CI, 10%-33%) in unvaccinated; and 53% (95% CI, 42%-64%) vs 9% (95% CI, 3%-22%) in unvaccinated (P < .0001 for each strain). At 7 months, the proportion of immunized students with titers ≥1:4 was 86% (95% CI, 71%-95%) against the isolate from the campus outbreak and 57% (95% CI, 41%-72%), 38% (95% CI, 24%-54%), and 31% (95% CI, 18%-47%), respectively, for the other 3 outbreak strains.

Conclusions

MenB-4C elicited short-term protective titers against 4 strains responsible for recent university campus outbreaks. By 7 months the prevalence of protective titers was <40% for 2 of the 4 outbreak strains. A booster dose of MenB-4C may be needed to maintain protective titers.

[Genotypes of Neisseria meningitidis isolates in patients with meningococcal meningitis in Paraguay, 1996-2015Genótipos de Neisseria meningitidis isolados de pacientes com doença meningocócica no Paraguai, 1996-2015]

Objetivo

Describir las características fenotípicas y genotípicas de cepas de Neisseria meningitidis aisladas de enfermedad meningocócica en Paraguay entre 1996 y 2015.

Métodos

Se estudiaron por métodos microbiológicos convencionales y técnicas moleculares 114 aislamientos de N. meningitidis y 12 muestras clínicas sin aislamiento confirmadas por reacción en cadena de la polimerasa (PCR) que fueron remitidas por los diferentes centros centinelas y centros colaboradores de Paraguay.

Resultados

El grupo de edad más afectado fue el de menores de 1 año (19,0%), seguido por el de 1 a 5 años (17,5%). Un mayor porcentaje de las cepas se aisló de casos de meningitis (81,7%) y el serogrupo B se encontró en 60,3% de los casos. Los fenotipos más frecuentes fueron B:4:P1.14 (16,0%), B:15:P1.5, C:NT:NST y W:NT:P1.2 (10,5%), respectivamente. Los complejos clonales prevalentes fueron ST-11/ET37 complex 29,6% (8/27) con predominio del serogrupo W (6/8), ST-35 complex 18,5% (5/27) en el serogrupo B (4/4), y ST-32/ET5 complex 14,8% (4/16) en el serogrupo B (5/5).

Conclusiones

En Paraguay la enfermedad meningocócica es relativamente infrecuente. Los análisis de distribución de serogrupo muestran que el más frecuente es el B y en los últimos dos años aumentaron los casos de enfermedad meningocócica por C y W. Los complejos clonales encontrados se correlacionan con los hallados en la región del Cono Sur. Debido al alto nivel de virulencia de N. meningitidis, su vigilancia debe constituir una prioridad estratégica de los sistemas de salud pública nacionales y regionales para prevenir brotes epidémicos y apoyar la toma de decisiones en salud pública.

Protecting UK adolescents and adults against meningococcal serogroup B disease

INTRODUCTION

Meningococcal serogroup B disease (MenB) is endemic in the UK and continues to cause the majority of invasive meningococcal disease. Two broadly protective protein-based MenB vaccines are now licensed and available, both with wide age indications. Whilst the UK recently became the first country to routinely vaccinate infants against MenB, a recommendation has not yet been extended to older age groups who can also now benefit from these vaccines.

AREAS COVERED

This review summarizes the evidence supporting the rationale for adolescents and adults in the UK to consider MenB vaccination.

EXPERT COMMENTARY

Although MenB disease is rare, the UK reports one of the highest annual incidence rates within the European region, with over a third of cases occurring in those aged 10+ years. Overall, the case fatality rate following MenB disease in the UK is 4.2% but can be more than twice as high in teenagers and adults than in infants, and survivors are often left with life-changing disabling sequelae. MenB outbreaks are unpredictable and continue to occur in regions where it is endemic. These outbreaks often affect students attending school or university, with living on a campus being an important risk factor. Concerned individuals in this age group should consider MenB vaccination.

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.

Prevention of Meningococcal Infection in the United States: Current Recommendations and Future Considerations

Neisseria meningitidis is a common cause of bacterial meningitis and septicemia that can lead to permanent sequelae or death. N meningitidis is classified into serogroups based on the composition of the capsular polysaccharide, with serogroups A, B, C, W, X, and Y recognized as the major disease-causing organisms. The unpredictability of infection coupled with the poor prognosis for some patients suggests immunization as an effective preventive strategy. Importantly, four of the six disease-causing serogroups (A, C, Y, and W) may be prevented with available quadrivalent capsular polysaccharide-protein conjugate vaccines; these vaccines have been successfully implemented into immunization programs in the United States. Unfortunately, quadrivalent conjugate vaccines are not effective against serogroup B, now the most common cause of invasive meningococcal disease. Two recombinant protein vaccines recently were licensed for prevention of serogroup B disease. Recommendations for use of these serogroup B vaccines in the United States have been made by the Advisory Committee on Immunization Practices. This article will discuss all available meningococcal vaccines, current recommendations for use, lessons learned from previous experiences, and future considerations, with the hope of further understanding how use of these vaccines may help reduce incidence of meningococcal disease in the United States.

Susceptibility of Meningococcal Strains Responsible for Two Serogroup B Outbreaks on U.S. University Campuses to Serum Bactericidal Activity Elicited by the MenB-4C Vaccine

In 2013 and 2014, two U.S. universities had meningococcal serogroup B outbreaks (a total of 14 cases) caused by strains from two different clonal complexes. To control the outbreaks, students were immunized with a serogroup B meningococcal vaccine (Novartis) that was not yet licensed in the United States. The vaccine (referred to as MenB-4C) contains four components capable of eliciting bactericidal activity. Both outbreak strains had high expression levels of two of the vaccine antigens (subfamily B factor H binding protein [FHbp] and neisserial heparin binding antigen [NHba]); the university B outbreak strain also had moderate expression of a third antigen, NadA. We investigated the bactericidal activity of sera from mice immunized with FHbp, NHba, or NadA and sera from MenB-4C-immunized infant macaques and an adult human. The postimmunization bactericidal activity of the macaque or human serum against isolates from university B with FHbp identification (ID) 1 that exactly matched the vaccine FHbp sequence variant was 8- to 21-fold higher than that against isolates from university A with FHbp ID 276 (96% identity to the vaccine antigen). Based on the bactericidal activity of mouse antisera to FHbp, NadA, or NHba and macaque or human postimmunization serum that had been depleted of anti-FHbp antibody, the bactericidal activity against both outbreak strains largely or entirely resulted from antibodies to FHbp. Thus, despite the high level of strain expression of FHbp from a subfamily that matched the vaccine antigen, there can be large differences in anti-FHbp bactericidal activity induced by MenB-4C vaccination. Further, strains with moderate to high NadA and/or NHba expression can be resistant to anti-NadA or anti-NHba bactericidal activity elicited by MenB-4C vaccination.

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.