Effectiveness of Meningococcal B Vaccine against Endemic Hypervirulent Neisseria meningitidis W Strain, England

Bacterial Extracellular Vesicles and Antimicrobial Peptides: A Synergistic Approach to Overcome Antimicrobial Resistance

Antimicrobial resistance is already a major global health threat, contributing to nearly 5 million deaths annually. The rise of multidrug-resistant pathogens has made many infections increasingly difficult to treat. This growing threat has driven the search for alternative therapeutic approaches. Among the most promising candidates are bacterial extracellular vesicles (BEVs) and antimicrobial peptides (AMPs), which offer unique mechanisms of action, potential synergistic effects, and the ability to bypass conventional resistance pathways. This review summarizes the current research on synergistic effects of BEVs and AMPs to overcome antimicrobial resistance.

Factor H binding protein (FHbp): An evaluation of genotypic diversity across Neisseria meningitidis serogroups

Neisseria meningitidis serogroups A, B, C, W, X, and Y cause invasive meningococcal disease (IMD) worldwide. Factor H binding protein (FHbp), a key meningococcal virulence factor, is an antigen included in both licensed meningococcal serogroup B (MenB) vaccines. This review examines the biology and epidemiology of FHbp and assesses the ability and potential of FHbp vaccine antigens to protect against IMD. Using evidence from the literature and the contemporary PubMLST database, we discuss analyses of MenB genotypes on the representation of the most prevalent multilocus sequence typing (MLST)/clonal complexes, FHbp subfamily distribution, and FHbp and porin A (PorA) variants. We further discuss that the similar genotypes, distribution, and diversity of FHbp variant types have remained stable over long time periods, supporting the potential for FHbp-containing, protein-based vaccines to protect against IMD, including MenB-FHbp (Trumenba®), which contains two lipidated FHbp antigens (one each from both FHbp subfamilies: A and B).

Whole-genome sequencing of Neisseria meningitidis collected in Chile from pediatric patients during 2016-2019 and coverage vaccine prediction

BACKGROUND

Over the past few years, whole-genome sequencing (WGS) has become a valuable tool for global meningococcal surveillance. The objective of this study was to genetically characterize Neisseria meningitidis strains isolated from children in Chile through WGS and predicting potential vaccine coverage using gMATS and MenDeVAR.

METHODS

WGS of 42 N.meningitidis from pediatric patients were processed and assembled using different software. We analyzed genomes with BIGSdb platform hosted at PubMLST.org, and predicted vaccine coverage using MenDeVAR and gMATS tools.

RESULTS

Among 42 strains, 25 were MenB, 16 MenW, and 1 MenC. The cc11 and cc 41/44 were the most frequents. The main frequent deduced peptide sequence for PorA was P1.5,2 (40 %), peptide P1.4 was present in one MenB strain; NHBA-29 (64 %), none having peptide 2; fHbp-2 (76 %), one strain had peptide-1, and two had peptide 45; NadA was detected in 52 %, peptide-6 was present in 84 %, none had peptide 8. The MenDeVAR index predicted a coverage in MenB strains for 4CMenB 8 % exact matches, 12 % cross-reactivity, 8 % not coverage and 64 % had insufficient data. gMATS predicted 16 % was covered, 8 % not covered and 76 % unpredictable, and overall coverage of 54 %. For rLP2086-fHbp, the MenDeVAR index predicted exact match in 8 %, cross-reactivity in 64 %, and insufficient data in 28 % and an overall coverage of 72 %. In non-MenB strains, the MenDeVAR index predicted for 4CMenB vaccine: cross-reactivity 88 %, 6 % for not covered and insufficient data. For rLP2086-fHbp, predicted cross-reactivity 12 % and insufficient data in 88 %. gMATS predicted an overall coverage of 50 % for Non-MenB.

CONCLUSION

genetic variability of the Chilean strains that its different from other countries, and until now limit the coverage prediction of vaccine with the available tools like gMATS and MenDeVAR.

Lifecycle model-based evaluation of infant 4CMenB vaccination in the UK

OBJECTIVES

Invasive meningococcal disease, an uncommon but severe disease, imposes catastrophic health and economic burdens. Cost-utility analysis (CUA) assumes separability in lifetime health and economic variables and cannot capture the full value of preventing such burdens. We overcome these limitations with a retrospective societal perspective cost-benefit analysis (CBA) of meningococcal serogroup B vaccination (4CMenB) of one infant cohort in the United Kingdom using a health-augmented lifecycle model (HALM) incorporating health's interactions with consumption, earnings, non-market time and financial risk.

METHODS

We used a static Markov model of vaccination's health impact and an HALM to estimate the private willingness to pay (PWTP) for the intrinsic and instrumental value of health under perfect capital markets, financial risk protection in the absence of insurance against permanent disability, parental spillovers, and acute phase disability. We estimated social WTP (SWTP) incorporating social severity preferences. We estimated rates of return that inform health payer reimbursement decisions, finance ministry budgeting decisions, and legislature taxation decisions. An expert Advisory Board investigated the validity of applying the HALM to infant 4CMenB.

RESULTS

The PWTP for a 2 + 1 vaccination schedule is £395, comprising £166 of disability insurance value, £79 of positive parental spillover value, £28 in the value of averting acute phase disability, and £122 in residual intrinsic and instrumental value of health. SWTP is £969.

CONCLUSIONS

HALM-based CBA provides an empirically richer, more utility-theoretically grounded approach to vaccine evaluation than CUA, demonstrating good value for money for legislatures (based on private values) and for all decision-makers (based on social values).

Bactericidal killing of meningococcal W strains isolated in Argentina by the sera of adolescents and infants immunized with 4-component meningococcal serogroup B vaccine (4CMenB)

Invasive meningococcal disease (IMD) is a life-threatening disease caused by meningococcal serogroups A, B, C, W, X, and Y, of which B and W are most common in Argentina. The 4-component meningococcal serogroup B (4CMenB) vaccine contains three purified recombinant protein antigens (Neisseria adhesin A [NadA], factor H binding protein [fHbp], and Neisserial Heparin Binding Antigen [NHBA]) and outer membrane vesicles (OMV), which is derived from the New Zealand epidemic strain and contains Porin A 1.4. These antigens are present and conserved in strains that belong to other serogroups. In this study, we show that 10/11 (91%) meningococcal serogroup W (MenW) strains selected to be representative of MenW isolates that caused IMD in Argentina during 2010-2011 were killed in bactericidal assays by the sera of adolescents and infants who had been immunized with the 4CMenB vaccine. We also show that MenW strains that caused IMD in Argentina during 2018-2021 were genetically similar to the earlier strains, indicating that the 4CMenB vaccine would likely still provide protection against current MenW strains. These data highlight the potential of 4CMenB vaccination to protect adolescents and infants against MenW strains that are endemic in Argentina.

The propositive study: Immunogenicity and safety of a four-component recombinant protein-based vaccine against MenB and a quadrivalent conjugate MenACWY vaccine in people living with HIV

BACKGROUND

People living with HIV have been shown to have an increased risk of invasive meningococcal disease. In some countries, meningococcal vaccines are now routinely recommended to all people living with HIV, but no study has yet assessed the immunogenicity and safety of a meningococcal serogroup B vaccine or the co-administration of a MenB and MenACWY vaccine in people living with HIV.

METHODS

This phase IV open-label clinical trial investigated the immunogenicity and safety of two doses of a four-component recombinant protein-based MenB vaccine (4CMenB) and a quadrivalent conjugate polysaccharide MenACWY vaccine (MenACWY-CRM197) given 1 month apart in a population of people living with HIV. Immunogenicity analysis was performed before vaccination and 1 month after the second doses of 4CMenB and MenACWY. Primary outcome measures were serum bactericidal assay geometric mean titres against three MenB reference strains at baseline and 1 month post vaccination, the proportion of participants achieving a putative protective titre of ≥4, and the proportion of participants with a ≥4-fold rise in titre from baseline. Secondary outcome measures were serum bactericidal assay geometric mean titres against MenA, C, W, and Y reference strains at baseline and 1 month post vaccination, the proportion achieving a putative protective titre of ≥8, and the proportion with a ≥4-fold rise in titre from baseline. Safety outcomes were solicited and unsolicited adverse events in the 7 days following vaccination. The trial was registered with clinicaltrials.gov (NCT03682939).

FINDINGS

In total, 55 participants aged 20-45 years were enrolled. All participants (100%; 95% confidence interval [CI] 93-100) achieved putative protective titres for two of the three MenB strains and for MenA, W, and Y. A total of 98% (95% CI 89-100) achieved a protective titre for the third MenB strain and 94% (95% CI 83-99) for MenC. No serious adverse events were reported.

INTERPRETATION

4CMenB and MenACWY were immunogenic and well-tolerated in a population of people living with HIV 1 month after two doses.

Epidemiology, clinical features and outcome of adults with meningococcal meningitis: a 15-year prospective nationwide cohort study

Background

We describe the epidemiology, clinical features and outcome of adult meningococcal meningitis in the Netherlands over a 15-year period.

Methods

We studied adults (age ≥ 16 years) who were listed by the Netherlands Reference Laboratory for Bacterial Meningitis and/or included in the prospective nationwide cohort study (MeninGene) between January 2006 and July 2021. Incidences were calculated per epidemiological year (July-June).

Findings

We identified 442 episodes of adult meningococcal meningitis. The median patient age was 32 years (IQR 18-55) and 226 episodes (51%) occurred in female patients. The annual incidence per 100,000 adults fluctuated, from 0.33 in 2006-2007 to 0.05 in 2020-2021, with a temporal increase up to 0.30 from 2016 to 2018, driven by an outbreak of serogroup W (MenW). Of 442 episodes, 274 episodes (62%) in 273 patients were included in the clinical cohort study. The overall case fatality rate was 4% (10 of 274) and 16% (43 of 274) had an unfavourable outcome (Glasgow Outcome Scale score 1-4). Compared to other serogroups, MenW was associated with higher rates of unfavourable outcome (6 of 16 [38%] vs. 37 of 251 [15%], P = 0.03) and death (4 of 16 [25%] vs. 6 of 251 [2%], P = 0.001).

Interpretation

The overall incidence of adult meningococcal meningitis in the Netherlands is low and outcome is generally favourable. An increase of MenW meningitis occurred from 2016 to 2018, which was associated with more unfavourable outcome and death.

Funding

Netherlands Organisation for Health Research and Development, European Research Council, National Institute of Public Health and Environmental protection.

Effectiveness of a Meningococcal Group B Vaccine (4CMenB) in Children

BACKGROUND

In September 2015, the four-component, protein-based meningococcal serogroup B vaccine (4CMenB; Bexsero) became available for private purchase in Spain.

METHODS

We conducted a nationwide matched case-control study to assess the effectiveness of 4CMenB in preventing invasive meningococcal disease in children. The study included all laboratory-confirmed cases of invasive meningococcal disease in children younger than 60 months of age between October 5, 2015, and October 6, 2019, in Spain. Each case patient was matched with four controls according to date of birth and province. 4CMenB vaccination status of the case patients and controls was compared with the use of multivariate conditional logistic regression.

RESULTS

We compared 306 case patients (243 [79.4%] with serogroup B disease) with 1224 controls. A total of 35 case patients (11.4%) and 298 controls (24.3%) had received at least one dose of 4CMenB. The effectiveness of complete vaccination with 4CMenB (defined as receipt of at least 2 doses, administered in accordance with the manufacturer's recommendations) was 76% (95% confidence interval [CI], 57 to 87) against invasive meningococcal disease caused by any serogroup, and partial vaccination was 54% (95% CI, 18 to 74) effective. Complete vaccination resulted in an effectiveness of 71% (95% CI, 45 to 85) against meningococcal serogroup B disease. Vaccine effectiveness with at least one dose of 4CMenB was 64% (95% CI, 41 to 78) against serogroup B disease and 82% (95% CI, 21 to 96) against non-serogroup B disease. With the use of the genetic Meningococcal Antigen Typing System, serogroup B strains that were expected to be covered by 4CMenB were detected in 44 case patients, none of whom had been vaccinated.

CONCLUSIONS

Complete vaccination with 4CMenB was found to be effective in preventing invasive disease by serogroup B and non-serogroup B meningococci in children younger than 5 years of age.

Correlates of protection for meningococcal surface protein vaccines; current approaches for the determination of breadth of coverage

INTRODUCTION

The two currently licensed surface protein non capsular meningococcal serogroup B (MenB) vaccines both have the purpose of providing broad coverage against diverse MenB strains. However, the different antigen compositions and approaches used to assess breadth of coverage currently make direct comparisons complex.

AREAS COVERED

In the second of two companion papers, we comprehensively review the serology and factors influencing breadth of coverage assessments for two currently licensed MenB vaccines.

EXPERT OPINION

Surface protein MenB vaccines were developed using different approaches, resulting in unique formulations and thus their breadth of coverage. The surface proteins used as vaccine antigens can vary among meningococcal strains due to gene presence/absence, sequence diversity and differences in protein expression. Assessment of the breadth of coverage provided by vaccines is influenced by the ability to induce cross-reactive functional immune responses to sequence diverse protein variants; the characteristics of the circulating invasive strains from specific geographic locations; methodological differences in the immunogenicity assays; differences in human immune responses between individuals; and the maintenance of protective antibody levels over time. Understanding the proportion of meningococcal strains which are covered by the two licensed vaccines is important in understanding protection from disease and public health use.

Real-world implementation of 4-component meningococcal serogroup B vaccine (4CMenB): implications for clinical practices

INTRODUCTION

Invasive meningococcal disease due to serogroup B (MenB) is an uncommon but life-threatening disease. The 4-component meningococcal serogroup B vaccine (4CMenB) is the only MenB vaccine with real-world evidence supporting a reduction in incidence without safety concerns.

AREAS COVERED

We reviewed recommendations and real-world implementation of 4CMenB in National Immunization Programs (NIPs) and implications for clinical practice through a non-systematic literature search.

EXPERT OPINION

4CMenB is registered in 45 countries, 33 of which recommend it clinically: nine for infants, children, adolescents, and high-risk groups; 11 for infants and high-risk groups; the US for individuals aged 16-23 years and high-risk groups; two for infants; 10 for high-risk groups and/or outbreak control. Dosing schedule varies between countries. To date, nine countries include 4CMenB in their NIP: UK, Andorra, Ireland, Italy, San Marino, Lithuania, Malta, Czech Republic, and Portugal. Australia funds it for Aboriginal and Torres Strait Islander children under 2 years, and high-risk individuals. South Australia funds for all infants and adolescents. Many factors influenced introduction into NIPs: disease burden, public awareness, cost-effectiveness, prior meningococcal vaccination programs, efficacy and safety profile. In the future, more countries might consider including 4CMenB in their NIP due to growing evidence on effectiveness and safety.

Product review on the IMD serogroup B vaccine Bexsero®

Bexsero® is a multicomponent vaccine composed of four major proteins of Neisseria meningitidis: the fHbp, NHBA, NadA and PorA. This vaccine was licensed against invasive meningococcal disease (IMD) due to serogroup B isolates. When administered alone, Bexsero® showed a safety profile similar to other childhood vaccines. It provides an excellent immunogenicity but that requires booster doses in infants and young children. Although the vaccine does not seem to impact on acquisition of carriage of serogroup B isolates, it confers protection against isolates of serogroup B harboring distinct but cross-reactive variants of fHbp, NadA and NHBA. Primary vaccination schemes in infancy underwent a rapid increase after a toddler booster suggesting an anamnestic response and the establishment of a memory response. As Bexsero® targets sub-capsular proteins that can be conserved regardless the capsule, the vaccine can be effective against non-B isolates such as isolates of serogroups W and X.

Looking beyond meningococcal B with the 4CMenB vaccine: the Neisseria effect

Infections with Neisseria meningitidis and Neisseria gonorrhoeae have different clinical manifestations, but the bacteria share up to 80-90% genome sequence identity. The recombinant meningococcal serogroup B (MenB) vaccine 4CMenB consists of four antigenic components that can be present in non-B meningococcal and gonococcal strains. This comprehensive review summarizes scientific evidence on the genotypic and phenotypic similarities between vaccine antigens and their homologs expressed by non-B meningococcal and gonococcal strains. It also includes immune responses of 4CMenB-vaccinated individuals and effectiveness and impact of 4CMenB against these strains. Varying degrees of strain coverage were estimated depending on the non-B meningococcal serogroup and antigenic repertoire. 4CMenB elicits immune responses against non-B meningococcal serogroups and N. gonorrhoeae. Real-world evidence showed risk reductions of 69% for meningococcal serogroup W clonal complex 11 disease and 40% for gonorrhea after 4CMenB immunization. In conclusion, functional antibody activity and real-world evidence indicate that 4CMenB has the potential to provide some protection beyond MenB disease.

'B Part of It' School Leaver study: a repeat cross-sectional study to assess the impact of increasing coverage with meningococcal B (4CMenB) vaccine on carriage of Neisseria meningitidis

BACKGROUND

Recombinant protein-based vaccines targeting serogroup B meningococci protect against invasive disease, but impacts on carriage are uncertain. This study assessed carriage prevalence of disease-associated meningococci from 2018-2020, as the proportion of vaccinated adolescents increased following introduction of a school-based 4CMenB immunisation program.

METHODS

Eligible participants who completed high school (age 17-25) in South Australia in the previous year had an oropharyngeal swab taken and completed a risk factor questionnaire. Disease-associated meningococci (genogroups A, B, C, W, X, Y) were detected by meningococcal and genogroup-specific polymerase chain reaction.

RESULTS

The final analysis included 4104 participants in 2018, 2690 in 2019, and 1338 in 2020. The proportion vaccinated with 4CMenB increased from 43% in 2018, to 78% in 2019, and 76% in 2020. Carriage prevalence of disease-associated meningococci in 2018 was 225/4104 (5.5%). There was little difference between the carriage prevalence in 2019 (134/2690, 5.0%, adjusted odds ratio [aOR] 0.82, 95% CI 0.64-1.05) and 2020 (68/1338, 5.1% aOR 0.82, 95% CI 0.57-1.17) compared to 2018.

CONCLUSIONS

Increased 4CMenB uptake in adolescents was not associated with a decline in carriage of disease-associated meningococci. 4CMenB immunisation programs should focus on direct (individual) protection for groups at greatest risk of disease.

Recent advances in meningococcal B disease prevention: real-world evidence from 4CMenB vaccination

OBJECTIVES

4CMenB is a broadly protective vaccine against invasive meningococcal capsular group B disease (MenB IMD). Licensed worldwide based on immunogenicity and safety data, effectiveness and impact data are now available. We comprehensively reviewed all available real-world evidence gathered from use of 4CMenB since licensure.

RESULTS

Data from 7 countries provide evidence of effectiveness and impact across different healthcare settings and age-groups, including national/regional immunization programs, observational studies and outbreak control. At least 2 4CMenB doses reduced MenB IMD by 50%-100% in 2-month to 20-year-olds depending on length of follow-up. Estimates of vaccine effectiveness in fully vaccinated cohorts ranged from 59%-100%. The safety profile of 4CMenB administered in real-world settings was consistent with pre-licensure clinical trial data.

CONCLUSION

MenB IMD is an uncommon but life-threatening disease with unpredictable epidemiology. The substantial body of data demonstrating 4CMenB effectiveness and impact supports its use in IMD prevention. The results reinforce the importance of direct protection of the highest risk groups; infants/young children and adolescents. Direct protection via routine infant immunization with catch-up in young children and routine adolescent vaccination could be the preferred option for MenB disease control. A Video Abstract linked to this article is available on Figshare: https://doi.org/10.6084/m9.figshare.14546790.

Molecular diagnostic assays for the detection of common bacterial meningitis pathogens: A narrative review

Bacterial meningitis is a major global cause of morbidity and mortality. Rapid identification of the aetiological agent of meningitis is essential for clinical and public health management and disease prevention given the wide range of pathogens that cause the clinical syndrome and the availability of vaccines that protect against some, but not all, of these. Since microbiological culture is complex, slow, and often impacted by prior antimicrobial treatment of the patient, molecular diagnostic assays have been developed for bacterial detection. Distinguishing between meningitis caused by Neisseria meningitidis (meningococcus), Streptococcus pneumoniae (pneumococcus), Haemophilus influenzae, and Streptococcus agalactiae and identifying their polysaccharide capsules is especially important. Here, we review methods used in the identification of these bacteria, providing an up-to-date account of available assays, allowing clinicians and diagnostic laboratories to make informed decisions about which assays to use.

Cross-reactivity of 4CMenB vaccine-induced antibodies against meningococci belonging to non-B serogroups in Italy

The four-component meningococcal serogroup B vaccine (4CMenB) contains antigens present in the majority of meningococci causing invasive meningococcal disease (IMD) and may potentially offer protection against strains belonging to non-B serogroups.This study aimed to evaluate the ability of 4CMenB-induced antibodies to kill, in a human serum bactericidal assay (hSBA), non-B meningococci belonging to the main genotypes responsible for IMD in Italy.Meningococci, collected between 2015 and 2017, was characterized for PorA, FetA and sequence type, and for clonal complex. Twenty non-B isolates, representative of the most frequent genotypes, were molecularly characterized for 4CMenB antigens and tested in hSBA with sera from 4CMenB-vaccinated infants and adolescents.Among twenty isolates, eleven were serogroup C, five were Y, two W and two X. All isolates contained genes encoding for fHbp and NHBA antigens and four harbored the NadA full-length encoding gene. Positive hSBA titers were obtained against all serogroup W, X and Y isolates and against five serogroup C isolates.These data show that the 4CMenB vaccine can induce bactericidal antibodies against genetically representative meningococcal W, Y and X strains from Italy. For serogroup C, different susceptibilities to killing were observed for strains with similar antigenic repertoires.

Association of Use of a Meningococcus Group B Vaccine With Group B Invasive Meningococcal Disease Among Children in Portugal

IMPORTANCE

A 4-component meningococcus group B vaccine (4CMenB) is the only vaccine in use to prevent group B invasive meningococcal disease in young children, but no matched controlled studies have evaluated it.

OBJECTIVE

To determine the association between receipt of 4CMenB and invasive group B meningococcal disease.

DESIGN, SETTING, AND PARTICIPANTS

Matched incidence density case-control study. Patients presenting from October 2014 to March 2019 were ascertained, with follow-up until death or discharge (last follow-up in June 2019) in 31 pediatric services in Portugal. Children and adolescent residents in Portugal with laboratory-confirmed invasive meningococcal disease were included. Controls, usually 2 per case, with unrelated conditions who were at the same hospital at the same time were matched for sex, age, and residence.

EXPOSURES

Immunization with 4CMenB, ascertained from the national database (2-4 doses are recommended, depending on age).

MAIN OUTCOMES AND MEASURES

The primary outcome was group B invasive meningococcal disease in fully vaccinated cases compared with controls. The secondary outcomes were all serogroup invasive meningococcal disease in fully vaccinated cases compared with controls and group B and all serogroup invasive meningococcal disease in cases compared with controls who received at least 1 vaccine dose.

RESULTS

Of 117 patients with invasive meningococcal disease, 98 were eligible for inclusion and 82 had group B invasive meningococcal disease; 69 were old enough to have been fully vaccinated and considered protected. Among these 69 cases, the median (interquartile range) age was 24 (4.5-196) months, 42 were male, and the median (interquartile range) duration of hospitalization was 8 (0-86) days. Five of 69 cases (7.2%) and 33 of 142 controls (23.1%) were fully vaccinated (difference, -16.0% [95% CI, -26.3% to -5.7%]; odds ratio [OR], 0.21 [95% CI, 0.08-0.55]). For all serogroup invasive meningococcal disease, 6 of 85 cases (7.1%) and 39 of 175 controls (22.3%) were fully vaccinated (difference, -15.2% [95% CI, -24.3% to -6.1%]; OR, 0.22 [95% CI, 0.09-0.53]). For group B disease, 8 of 82 cases (9.8%) and 50 of 168 controls (29.8%) received at least 1 vaccine dose (difference, -20.0% [95% CI, -30.3% to -9.7%]; OR, 0.18 [95% CI, 0.08-0.44]) and for all serogroup invasive meningococcal disease, 11 of 98 cases (11.2%) and 61 of 201 controls (30.3%) received at least 1 vaccine dose (difference, -19.1% [95% CI, -28.8% to -9.5%]; OR, 0.23 [95% CI, 0.11-0.49]).

CONCLUSIONS AND RELEVANCE

During the first 5 years of vaccine availability in Portugal, vaccination with 4CMenB was less likely among children who developed invasive meningococcal disease compared with matched controls without invasive meningococcal disease. These findings may help inform the use of the 4CMenB vaccine in clinical practice.

TRIAL REGISTRATION

ISRCTN Identifier: ISRCTN10901628.

4CMenB Immunization Induces Serum Bactericidal Antibodies Against Non-Serogroup B Meningococcal Strains in Adolescents

Introduction

Invasive meningococcal disease (IMD) is an important public health concern. In developed countries, most IMD is caused by meningococcal serogroup B (MenB) and two protein-based MenB vaccines are currently available: the four-component vaccine 4CMenB (Bexsero, GSK) and the bivalent vaccine MenB-FHbp (Trumenba, Pfizer). Genes encoding the 4CMenB vaccine antigens are also present in strains belonging to other meningococcal serogroups.

Methods

To evaluate the potential of 4CMenB vaccination to protect adolescents against non-MenB IMD, we tested the bactericidal activity of sera from immunized adolescents on 147 (127 European and 20 Brazilian) non-MenB IMD isolates, with a serum bactericidal antibody assay using human complement (hSBA). Serum pools were prepared using samples from randomly selected participants in various clinical trials, pre- and post-vaccination: 12 adolescents who received two doses of 4CMenB 2 months apart, and 10 adolescents who received a single dose of a MenACWY conjugate vaccine (as positive control).

Results

4CMenB pre-immune sera killed 7.5% of the 147 non-MenB isolates at hSBA titers ≥ 1:4. In total, 91 (61.9%) tested isolates were killed by post-dose 2 pooled sera at hSBA titers ≥ 1:4, corresponding to 44/80 (55.0%) MenC, 26/35 (74.3%) MenW, and 21/32 (65.6%) MenY isolates killed.

Conclusion

4CMenB vaccination in adolescents induces bactericidal killing of non-MenB isolates, suggesting that mass vaccination could impact IMD due to serogroups other than MenB.

Predicted coverage by 4CMenB vaccine against invasive meningococcal disease cases in the Netherlands

Neisseria meningitidis serogroup B is a major cause of invasive meningococcal disease in Europe. In the absence of a conjugate serogroup B vaccine, a subcapsular 4CMenB vaccine was developed. Data on 4CMenB vaccine efficacy is still limited. Recently, genomic MATS (Meningococcal Antigen Typing System) was developed as a tool to predict strain coverage, using vaccine antigens sequence data. We characterized all invasive meningococcal isolates received by the Netherlands Reference Laboratory for Bacterial Meningitis (NRLBM) in two epidemiological years 2017-2019 using whole-genome sequencing and determined serogroup, clonal complex (cc) and estimated 4CMenB vaccine coverage by gMATS. Of 396 cases of invasive meningococcal disease, corresponding to an incidence of 1.22 cases/10⁵ inhabitants, 180 (45%) were serogroup W, 155 (39%) serogroup B, 46 (12%) serogroup Y, 10 (3%) serogroup C, 2 non-groupable (0.5%) and 3 (0.7%) unknown. The incidence was the highest among 0-4 years olds (4 cases/10⁵ inhabitants), and 57/72 (79%) of these cases were serogroup B. Serogroup W predominated among persons 45 years of age or older with 110/187 (59%) cases. Serogroup B isolates comprised 11 different clonal complexes, with 103/122 (84%) isolates belonging to 4 clonal complexes: cc32, cc41/44, cc269 and cc213. In contrast, serogroup W isolates were genetically similar with 95% belonging to cc11. Of 122 serogroup B isolates, 89 (73%; 95% CI: 64-80%) were estimated to be covered by 4CMenB and the degree of coverage varied largely by clonal complex and age. Among the 0-4 year olds, 25 of 43 (58%; 95% CI: 43-72%) MenB isolates were estimated to be covered. Since the coverage of the 4CMenB vaccine is dependent on circulating clonal complexes, our findings emphasize the need for surveillance of circulating meningococcal strains. In addition, estimation of age specific coverage is relevant to determine the right target age group for vaccination.

Multicomponent meningococcal serogroup B vaccination elicits cross-reactive immunity in infants against genetically diverse serogroup C, W and Y invasive disease isolates

BACKGROUND

The multicomponent meningococcal serogroup B vaccine (4CMenB) is currently indicated for active immunization against invasive meningococcal disease caused by Neisseria meningitidis serogroup B (MenB). However, genes encoding the 4CMenB antigens are also variably present and expressed in strains belonging to other meningococcal serogroups. In this study, we evaluated the ability of antibodies raised by 4CMenB immunisation to induce complement-mediated bactericidal killing of non-MenB strains.

METHODS

A total of 227 invasive non-MenB disease isolates were collected between 1 July 2007 and 30 June 2008 from England and Wales, France, and Germany; 41 isolates were collected during 2012 from Brazil. The isolates were subjected to genotypic analyses. A subset of 147 isolates (MenC, MenW and MenY) representative of the meningococcal genetic diversity of the total sample were tested in the human complement serum bactericidal antibody assay (hSBA) using sera from infants immunised with 4CMenB.

RESULTS

Serogroup and clonal complex repertoires of non-MenB isolates were different for each country. For the European panel, MenC, MenW and MenY isolates belonged mainly to ST-11, ST-22 and ST-23 complexes, respectively. For the Brazilian panel, most MenC and MenW isolates belonged to the ST-103 and ST-11 complexes, respectively, and most MenY isolates were not assigned to clonal complexes. Of the 147 non-MenB isolates, 109 were killed in hSBA, resulting in an overall coverage of 74%.

CONCLUSION

This is the first study in which 147 non-MenB serogroup isolates have been analysed in hSBA to evaluate the potential of a MenB vaccine to cover strains belonging to other serogroups. These data demonstrate that antibodies raised by 4CMenB are able to induce bactericidal killing of 109 non-MenB isolates, representative of non-MenB genetic and geographic diversity. These findings support previous evidence that 4CMenB immunisation can provide cross-protection against non-MenB strains in infants, which represents an added benefit of 4CMenB vaccination.

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.

First real world evidence of meningococcal group B vaccine, 4CMenB, protection against meningococcal group W disease; prospective enhanced national surveillance, England

BACKGROUND

4CMenB is a protein-based meningococcal group B vaccine but the vaccine antigens may also be present on non-group B meningococci. In September 2015, the UK implemented 4CMenB into the national infant immunisation programme, alongside an emergency adolescent meningococcal ACWY (MenACWY) programme to control a national outbreak of group W (MenW) disease caused by a hypervirulent strain belonging to the ST11 clonal complex. The adolescent programme aimed to provide direct protection for adolescents and, over time, indirect (herd) protection across the population.

METHODS

Public Health England conducts meningococcal disease surveillance in England. MenW cases confirmed during four years before and four years after implementation of both vaccines were analysed. Poisson models were constructed to estimate direct protection against MenW disease offered by the infant 4CMenB programme on top of the indirect impact of the adolescent MenACWY programme in children eligible for 4CMenB but not MenACWY.

RESULTS

Model estimates showed 69% (adjusted incidence rate ratio (IRR) 0.31, 95%CI, 0.20-0.67) and 52% (aIRR 0.48, 95%CI 0.28-0.81) fewer MenW cases than predicted among age-cohorts that were fully-eligible and partly-eligible for 4CMenB, respectively. There were 138 MenW cases in &5 year-olds. 4CMenB directly prevented 98 (95%CI, 34-201) cases, while the MenACWY programme indirectly prevented an additional 114 (conservative) to 899 (extreme) cases over four years. Disease severity was similar in 4CMenB-immunised and unimmunised children.

CONCLUSIONS

Our results provide the first real-world evidence of the direct protection afforded by 4CMenB against MenW:cc11 disease. 4CMenB has the potential to provide some protection against all meningococcal serogroups.

Success of 4CMenB in preventing meningococcal disease: evidence from real-world experience

Meningococcal disease remains one of the most feared infectious diseases worldwide because of its sudden onset, rapid progression and high case fatality rates, while survivors are often left with severe long-term sequelae. Young children have the highest incidence of invasive meningococcal disease (IMD), and nearly all cases in the UK, as in most of Europe and many other industrialised countries, are due to group B meningococci (MenB). The licensure of a broad-coverage, recombinant protein-based MenB vaccine (4CMenB) in 2013 was, therefore, heralded a major breakthrough in the fight against IMD. This vaccine was, however, licensed on immunogenicity and reactogenicity studies only, raising uncertainties about field effectiveness, long-term safety and antibody persistence. In 2015, the UK became the first country to implement 4CMenB into the national infant immunisation schedule and, since then, several countries have followed suit. Seven years after licensure, a wealth of real-world data has emerged to confirm 4CMenB effectiveness, along with large-scale safety data, duration of protection in different age groups, successful strategies to reduce vaccine reactogenicity, impact on carriage in adolescents and the potential for 4CMenB to protect against other meningococcal serogroups and against gonorrhoea. A number of questions, however, remain unanswered, including the investigation and management of vaccine-associated fever in infants, as well as disease severity and assessment of breakthrough cases in immunised children. Increasing use of 4CMenB will provide answers in due course. We now have vaccines against all the major serogroups causing IMD worldwide. Next-generation and combination vaccines against multiple serogroups look very promising.

Methods to evaluate serogroup B meningococcal vaccines: From predictions to real-world evidence

Serogroup B meningococci (MenB) remain a prominent cause of invasive meningococcal disease (IMD). The protein-based multicomponent 4CMenB and the bivalent MenB-FHbp are the only currently available vaccines against MenB-caused IMD. Efficacy studies are not possible, due to the low incidence of IMD. Therefore, the vaccines' immunogenicity has been evaluated against several target strains chosen to quantify complement-mediated killing induced by each vaccine component in the serum bactericidal antibody assay. However, due to the wide genetic diversity and different expression levels of vaccine antigens across MenB strains, vaccine performance may differ from one strain to another. Here, we review the methods used to predict MenB strain coverage for 4CMenB and MenB-FHbp. Phenotypic assays such as the meningococcal antigen typing system (MATS, 4CMenB-specific) and the flow cytometric meningococcal antigen surface expression assay (MEASURE; MenB-FHbp-specific) were developed. Genomic approaches are also available, such as genetic MATS (gMATS) and the Bexsero antigen sequence type (BAST) scheme, both 4CMenB-specific. All methods allow tentative predictions of coverage across MenB strains, including that afforded by each vaccine antigen, and are rapid and reproducible. Real-world data on vaccine effectiveness are needed to confirm predictions obtained by these methods.

Cocirculation of Hajj and non-Hajj strains among serogroup W meningococci in Italy, 2000 to 2016

In Italy, B and C are the predominant serogroups among meningococci causing invasive diseases. Nevertheless, in the period from 2013 to 2016, an increase in serogroup W Neisseria meningitidis (MenW) was observed. This study intends to define the main characteristics of 63 MenW isolates responsible of invasive meningococcal disease (IMD) in Italy from 2000 to 2016. We performed whole genome sequencing on bacterial isolates or single gene sequencing on culture-negative samples to evaluate molecular heterogeneity. Our main finding was the cocirculation of the Hajj and the South American sublineages belonging to MenW/clonal complex (cc)11, which gradually surpassed the MenW/cc22 in Italy. All MenW/cc11 isolates were fully susceptible to cefotaxime, ceftriaxone, ciprofloxacin, penicillin G and rifampicin. We identified the full-length NadA protein variant 2/3, present in all the MenW/cc11. We also identified the fHbp variant 1, which we found exclusively in the MenW/cc11/Hajj sublineage. Concern about the epidemic potential of MenW/cc11 has increased worldwide since the year 2000. Continued surveillance, supported by genomic characterisation, allows high-resolution tracking of pathogen dissemination and the detection of epidemic-associated strains.

Strain coverage of Bexsero vaccine assessed by whole-genome sequencing over a cohort of invasive meningococci of serogroups B and W isolated in Switzerland

Invasive meningococcal disease (IMD), caused by Neisseria meningitidis (Nm) strains, is a life-threatening but vaccine-preventable condition. Bexsero is a four-component vaccine that offers broad protection against Nm of serogroup B (NmB), particularly common in Europe. In Switzerland, Bexsero has not yet been licensed and no information is available concerning the predicted vaccine coverage on isolates of circulating Nm. We performed genotyping of Bexsero antigen loci by whole-genome sequencing (WGS) on 104 NmB collected in Switzerland in the 2010-2015 period. We searched for antigen variants previously defined as predictors of strain coverage and estimated that 50% of IMD NmB strains were potentially covered by the vaccine. Clonal complexes (cc) 32, 41/44 and 269, considered the best covered lineages, were further sub-typed according to Bexsero Antigen Sequence Type (BAST) scheme. We also genotyped by WGS 40 Nm of serogroup W (NmW) collected in the country between 2010 and 2016. NmW cc22 isolates appeared to be covered by the vaccine, which was not the case for cc11 isolates, whose incidence has recently increased in Switzerland and all over Europe. Our work underlines the benefit of using WGS for surveillance of vaccine antigen variant distribution in local Nm population and taking proper measures to prevent the spread of NmB.

Transmissibility and pathogenicity of the emerging meningococcal serogroup W sequence type-11 complex South American strain: a mathematical modeling study

BACKGROUND

The recent emergence of strains belonging to the meningococcal serogroup W (MenW) sequence type-11 clonal complex and descending from the South American sub-lineage (MenW:cc11/SA) has caused significant shifts in the epidemiology of meningococcal disease worldwide. Although MenW:cc11/SA is deemed highly transmissible and invasive, its epidemiological characteristics have not yet been quantified.

METHODS

We designed a mathematical model of MenW transmission, carriage, and infection to analyze the recent epidemiology of invasive disease caused by MenW:cc11/SA strains and by other MenW strains in England and in France. We confronted that model with age-stratified incidence data to estimate the transmissibility and the invasiveness of MenW:cc11/SA in England, using the data in France as a validation cohort.

RESULTS

During the epidemiological years 2010/2011-2014/2015 in England, the transmissibility of MenW:cc11/SA relative to that of other MenW strains was estimated at 1.20 (95% confidence interval, 1.15 to 1.26). The relative invasiveness of MenW:cc11/SA was also found to exceed unity and to increase with age, with estimates ranging from 4.0 (1.6 to 9.7) in children aged 0-4 years to 20 (6 to 34) in adults aged ≥ 25 years. In France, the model calibrated in England correctly reproduced the early increase of MenW:cc11/SA disease during 2012/2013-2016/2017. Most recent surveillance data, however, indicated a decline in MenW:cc11/SA disease. In both countries, our results suggested that the transmission of MenW:cc11/SA carriage possibly started several months before the first reported case of MenW:cc11/SA disease.

DISCUSSION

Our results confirm earlier suggestions about the transmission and the pathogenic potential of MenW:cc11/SA. The main limitation of our study was the lack of age-specific MenW carriage data to confront our model predictions with. Furthermore, the lesser model fit to the most recent data in France suggests that the predictive accuracy of our model might be limited to 5-6 years.

CONCLUSIONS

Our study provides the first estimates of the transmissibility and of the invasiveness of MenW:cc11/SA. Such estimates may be useful to anticipate changes in the epidemiology of MenW and to adapt vaccination strategies. Our results also point to silent, prolonged transmission of MenW:cc11/SA carriage, with potentially important implications for epidemic preparedness.

Emergence of new genetic lineage, ST-9316, of Neisseria meningitidis group W in Hauts-de-France region, France 2013-2018

BACKGROUND

The epidemiology of invasive meningococcal disease (IMD) is continuously changing in incidence, age distribution and/or the expansion of new strains of Neisseria meningitidis. The epidemiology of IMD due to group W (IMDW) has changed recently at a global level with the emergence of isolates belonging to the clonal complex ST-11 (CC11) derived from the South America-UK strain. A more recent change has been detected in France with the emergence of a new genotype distinct from CC11 that we aimed to analyse.

METHODS

Epidemiological and microbiological surveillance data in France were used in combination with whole genome sequencing (WGS) to detect emerging phenotypes and genotypes of IMD causing strains, and their susceptibility to immunity induced by the 4CMenB vaccine. Transgenic mice expressing the human transferrin were used to analyse the virulence of emerging strain isolates by direct comparison with CC11 isolates.

FINDINGS

Our data showed a local increase of IMDW isolates in north France since 2013. The isolates belonged to ST-9316 and few were ST-11 isolates. WGS clustered ST-9316 isolates together and were distantly separated from the isolates of the clonal complex ST-11 (CC11). Unlike cases due to W/CC11 isolates, cases due to W/ST-9316 isolates were mostly observed amongst infants under the age of 1 year but with lower mortality compared to W/CC11 cases. Genomic comparison showed that the W/ST-9316, unlike W/CC11 isolates, lacked the hmbR gene encoding the haemoglobin receptor that is a virulence factor involved in the acquisition of iron from haemoglobin. W/ST-9316 further showed lower virulence in mice compared to W/CC11 isolates.

INTERPRETATION

We report the emergence of a novel sequence type (ST-9316) mostly associated with serogroup W, and exhibiting a lower virulence and a distinct age specific incidence profile than W/CC11 isolates. Surveillance requires powerful approaches combining WGS and pathophysiological analysis to adapt control measures.

WGS analysis of a penicillin-resistant Neisseria meningitidis strain containing a chromosomal ROB-1 β-lactamase gene

Objectives

Neisseria meningitidis is rarely penicillin resistant. We describe WGS analysis of a penicillin-resistant N. meningitidis collected from a case of invasive meningococcal disease.

Methods

Serogrouping, serotyping and serosubtyping were performed with specific antibodies. β-Lactamase was detected by nitrocefin. MICs were determined by Etest and agar dilution. Sequencing of N. meningitidis genomes was done on the Illumina MiSeq platform and genome data were analysed using the Bacterial Isolate Genome Sequence Database (BIGSdb) on the PubMLST Neisseria website (https://pubmlst.org/neisseria/). Transformation was used to confirm the genetic basis of the penicillin resistance.

Results

An N. meningitidis blood isolate from a female patient in her mid-50s with a painful and septic left shoulder was found to have penicillin MIC values of 3–12 mg/L. The isolate was typed as Y: 14, 19: P1.– and ST3587, and was weakly β-lactamase positive. WGS analysis identified a full-length copy of the β-lactamase gene bla_ROB-1, which was contained on a 1719 bp insert with a G + C content of 41.7% (versus a G + C content of N. meningitidis of 51.7%), suggesting that the bla_ROB-1 gene came from a different bacterial species. A GenBank analysis of the bla_ROB-1 gene insert found 99.77% identity with a DNA segment found in plasmid pB1000′ from Haemophilus influenzae. Transformation of a penicillin-susceptible strain with the bla_ROB-1 gene conferred β-lactamase activity and penicillin resistance.

Conclusions

N. meningitidis serogroup Y, ST3587 can carry and express the bla_ROB-1 gene, leading to penicillin resistance. It is highly likely that the N. meningitidis isolate acquired the bla_ROB-1 gene from H. influenzae.

Distribution of Neisseria meningitidis serogroup b (NmB) vaccine antigens in meningococcal disease causing isolates in the United States during 2009-2014, prior to NmB vaccine licensure

OBJECTIVES

Two Neisseria meningitidis serogroup B (NmB) vaccines are licensed in the United States. To estimate their potential coverage, we examined the vaccine antigen diversity among meningococcal isolates prior to vaccine licensure.

METHODS

NmB vaccine antigen genes of invasive isolates collected in the U.S. from 2009 to 2014 were characterized by Sanger or whole-genome sequencing.

RESULTS

During 2009-2014, the predominant antigen types have remained similar to those reported in 2000-2008 for NmB and 2006-2008 for NmC, NmY, with the emergence of a few new types. FHbp of subfamily B or variant 1 (B/v1) remained prevalent among NmB whereas FHbp of subfamily A or variant 2 and 3 (A/v2-3) were more prevalent among non-NmB. FHbp peptide 1 (B24/1.1) remains the most prevalent type in NmB. Full-length NadA peptide was detected in 26% of isolates, primarily in NmB and NmW. The greatest diversity of NhbA peptides was detected among NmB, with p0005 as the most prevalent type.

CONCLUSIONS

The prevalence and diversity of the NmB vaccine antigens have remained stable with common antigen types persisting over time. The data collected prior to NmB vaccine licensure provide the baseline to understand the potential impact of NmB vaccines on antigen diversity and strain coverage.

Epidemiologic Trends, Global Shifts in Meningococcal Vaccination Guidelines, and Data Supporting the Use of MenACWY-TT Vaccine: A Review

Neisseria meningitidis is a major cause of meningitis and septicemia with cases, outbreaks, and epidemics reported globally in industrialized and non-industrialized countries. N. meningitidis is categorized into 12 serogroups; however, only 5 serogroups (A, B, C, W, Y) are responsible for the majority of disease. Invasive meningococcal disease (IMD) occurs unpredictably; protection is therefore best achieved by initiating proactive vaccination strategies. Vaccines are currently available for the five main disease-causing serogroups. With the evolution of meningococcal vaccines and changes in IMD epidemiology, different vaccination strategies have been used. Recently, the rapid clonal expansion of meningococcal serogroup W (MenW) has been associated with a change in the national and regional vaccination recommendations from monovalent meningococcal serogroup C vaccines to meningococcal serogroup A, C, W, Y (MenACWY) vaccines in several countries. This review highlights these and other changes in IMD epidemiology and meningococcal vaccination recommendations, summarizes information available for currently available conjugate MenACWY vaccines, and focuses on clinical study data for the most recently approved MenACWY conjugate vaccine, MenACWY vaccine conjugated to tetanus toxoid (MenACWY-TT). MenACWY-TT studies spanned multiple age groups and generally demonstrated safety and immunogenicity in comparison with other meningococcal vaccines and under concomitant administration of other routine vaccines. Continuous updates to meningococcal vaccine recommendations in response to changing epidemiology, as have been undertaken for MenW, are necessary to ensure optimal population protection. FUNDING: Pfizer, Inc.

Meningococcal vaccines in Australia: a 2019 update

Invasive meningococcal disease is a rare but serious infection caused by Neisseria meningitidis

Serogroup B was the predominant serogroup causing invasive meningococcal disease in Australia until 2015. Serogroup W disease has increased substantially since 2014, and in 2017, serogroups B and W caused similar numbers of invasive disease cases

Vaccines against serogroups A, C, W, Y and B are available for anyone who wishes to reduce the risk of meningococcal disease

Vaccination is strongly recommended for people in high-risk age or population groups. These are children under 2 years, 15–19 year olds, Aboriginal and Torres Strait Islander children, and people with medical, occupational, behavioural or travel-related risk factors for invasive meningococcal disease

Meningococcal ACWY vaccine is funded under the National Immunisation Program for babies aged 12 months. Since April 2019, it has been funded for year 10 students through a school program. There are additional state and territory-based programs for both meningococcal ACWY and meningococcal B vaccines

Evaluating the Effectiveness of Vaccines Using a Regression Discontinuity Design

The regression discontinuity design (RDD), first proposed in the educational psychology literature and popularized in econometrics in the 1960s, has only recently been applied to epidemiologic research. A critical aim of infectious disease epidemiologists and global health researchers is to evaluate disease prevention and control strategies, including the impact of vaccines and vaccination programs. RDDs have very rarely been used in this context. This quasi-experimental approach using observational data is designed to quantify the effect of an intervention when eligibility for the intervention is based on a defined cutoff such as age or grade in school, making it ideally suited to estimating vaccine effects given that many vaccination programs and mass-vaccination campaigns define eligibility in this way. Here, we describe key features of RDDs in general, then specific scenarios, with examples, to illustrate that RDDs are an important tool for advancing our understanding of vaccine effects. We argue that epidemiologic researchers should consider RDDs when evaluating interventions designed to prevent and control diseases. This approach can address a wide range of research questions, especially those for which randomized clinical trials would present major challenges or be infeasible. Finally, we propose specific ways in which RDDs could advance future vaccine research.

Exploitation of Neisseria meningitidis Group B OMV Vaccines Against N. gonorrhoeae to Inform the Development and Deployment of Effective Gonorrhea Vaccines

Have potential clues to an effective gonorrhea vaccine been lurking in international disease surveillance data for decades? While no clinically effective vaccines against gonorrhea have been developed we present direct and indirect evidence that a vaccine is not only possible, but may already exist. Experience from Cuba, New Zealand, and Canada suggest that vaccines containing Group B Neisseria meningitides outer membrane vesicles (OMV) developed to control type-specific meningococcal disease may also prevent a significant proportion of gonorrhea. The mechanisms for this phenomenon have not yet been elucidated but we present some strategies for unraveling potential cross protective antigens and effector immune responses by exploiting stored sera from clinical trials and individuals primed with a meningococcal group B OMV vaccine (MeNZB). Elucidating these will contribute to the ongoing development of high efficacy vaccine options for gonorrhea. While the vaccine used in New Zealand, where the strongest empirical evidence has been gathered, is no longer available, the OMV has been included in the multi component recombinant meningococcal vaccine 4CMenB (Bexsero) which is now licensed and used in numerous countries. Several lines of evidence suggest it has the potential to affect gonorrhea prevalence. A vaccine to control gonorrhea does not need to be perfect and modeling supports that even a moderately efficacious vaccine could make a significant impact in disease prevalence. How might we use an off the shelf vaccine to reduce the burden of gonorrhea? What are some of the potential societal barriers in a world where vaccine hesitancy is growing? We summarize the evidence and consider some of the remaining questions.

MenB-FHbp Meningococcal Group B Vaccine (Trumenba®): A Review in Active Immunization in Individuals Aged ≥ 10 Years

MenB-FHbp (bivalent rLP2086; Trumenba^®) is a recombinant protein-based vaccine targeting Neisseria meningitidis serogroup B (MenB), which has recently been licensed in the EU for active immunization to prevent invasive disease caused by MenB in individuals ≥ 10 years of age. The vaccine, which contains a variant from each of the two identified subfamilies of the meningococcal surface protein factor H-binding protein (fHBP), has been licensed in the USA for active immunization in individuals 10-25 years of age since 2014. This article reviews the immunogenicity, reactogenicity and tolerability of MenB-FHbp, with a focus on the EU label and the European setting. As demonstrated in an extensive program of clinical trials in adolescents and young adults, a two-dose or three-dose series of MenB-FHbp elicits a strong immune response against a range of MenB test strains selected to be representative of strains prevalent in Europe and the USA. Follow-up studies investigating the persistence of the MenB-FHbp immune response and the effect of a booster dose of the vaccine indicate that a booster dose should be considered (following a primary vaccine series) in individuals at continued risk of invasive meningococcal disease. MenB-FHbp vaccine appears to be moderately reactogenic but, overall, is generally well tolerated, with most adverse reactions being mild to moderate in severity. Although post-marketing, population-based data will be required to establish the true effectiveness of the vaccine, currently available data indicate that MenB-FHbp, in a two-dose or three-dose series, is likely to provide broad protection against MenB strains circulating in Europe.

Optimizing the timing of 4CMenB vaccination in adolescents and young adults based on immune persistence and booster response data

INTRODUCTION

Meningococcal disease has an incidence peak spread over several years during adolescence and young adulthood in the United States. Meningococcal serogroup B (MenB) vaccines have been introduced relatively recently and may help protect individuals in these age groups. Currently there is insufficient long-term experience to determine the duration of disease protection after any MenB vaccine. Understanding antibody persistence after primary vaccination and responses to booster can help inform MenB vaccination strategies and optimize disease prevention. Areas covered: Four studies in adolescents/young adults vaccinated with meningococcal B vaccine 4CMenB were reviewed with the aim to compare findings across studies and draw key learnings. The studies varied by geographic location, population characteristics, and timing of antibody measurement relative to primary vaccination. Expert opinion: Antibody persistence data for 4CMenB are substantial, extending 7.5 years post-primary vaccination. Vaccination at age 16-18 years may help protect adolescents throughout their highest age-based risk period. Similar robust responses to a single booster dose were observed 4 and 7.5 years after primary vaccination. In outbreak settings it is beneficial to have received prior vaccination; residual circulating antibodies may provide protection, and a single dose induces booster responses within 7 days, which is quicker than administration of a 2-dose series to vaccine-naïve individuals.

Genomic Surveillance of 4CMenB Vaccine Antigenic Variants among Disease-Causing Neisseria meningitidis Isolates, United Kingdom, 2010-2016

In September 2015, 4CMenB meningococcal vaccine was introduced into the United Kingdom infant immunization program without phase 3 trial information. Understanding the effect of this program requires enhanced surveillance of invasive meningococcal disease (IMD) Neisseria meningitidis isolates and comparison with prevaccination isolates. Bexsero Antigen Sequence Types (BASTs) were used to analyze whole-genome sequences of 3,073 prevaccine IMD N. meningitidis isolates obtained during 2010−2016. Isolates exhibited 803 BASTs among 31 clonal complexes. Frequencies of antigen peptide variants were factor H binding protein 1, 13.4%; Neisserial heparin-binding antigen 2, 13.8%; Neisseria adhesin A 8, 0.8%; and Porin A-VR2:P1.4,10.9%. In 2015−16, serogroup B isolates showed the highest proportion (35.7%) of exact matches to >1 Bexsero components. Serogroup W isolates showed the highest proportion (93.9%) of putatively cross-reactive variants of Bexsero antigens. Results highlighted the likely role of cross-reactive antigens. BAST surveillance of meningococcal whole-genome sequence data is rapid, scalable, and portable and enables international comparisons of isolates.

The Global Meningococcal Initiative meeting on prevention of meningococcal disease worldwide: Epidemiology, surveillance, hypervirulent strains, antibiotic resistance and high-risk populations

INTRODUCTION

The 2018 Global Meningococcal Initiative (GMI) meeting focused on evolving invasive meningococcal disease (IMD) epidemiology, surveillance, and protection strategies worldwide, with emphasis on emerging antibiotic resistance and protection of high-risk populations. The GMI is comprised of a multidisciplinary group of scientists and clinicians representing institutions from several continents.

AREAS COVERED

Given that the incidence and prevalence of IMD continually varies both geographically and temporally, and surveillance systems differ worldwide, the true burden of IMD remains unknown. Genomic alterations may increase the epidemic potential of meningococcal strains. Vaccination and (to a lesser extent) antimicrobial prophylaxis are the mainstays of IMD prevention. Experiences from across the globe advocate the use of conjugate vaccines, with promising evidence growing for protein vaccines. Multivalent vaccines can broaden protection against IMD. Application of protection strategies to high-risk groups, including individuals with asplenia, complement deficiencies and human immunodeficiency virus, laboratory workers, persons receiving eculizumab, and men who have sex with men, as well as attendees at mass gatherings, may prevent outbreaks. There was, however, evidence that reduced susceptibility to antibiotics was increasing worldwide.

EXPERT COMMENTARY

The current GMI global recommendations were reinforced, with several other global initiatives underway to support IMD protection and prevention.

Would immunization be the same without cross-reactivity?

"Cross-reactivity" (the observed immune response against pathogen types not specifically targeted by the vaccine antigen composition) and "cross-protection" (clinical protection against related non-vaccine microorganism types) are vaccinology concepts that are attracting renewed interest in the context of disease prevention. National health authorities are collecting mounting evidence of the importance of cross-reactivity. For some vaccines, this has been substantiated by cross-protection data from clinical studies and/or post-licensure data, where their introduction into immunization programmes has shown beneficial impacts on disease caused by related non-vaccine microorganisms. This knowledge has influenced the way new vaccines are designed, developed, and evaluated in real-life settings. Some of the new vaccines are now designed with the specific aim of having a greater breadth of protection. Ideal vaccine antigens therefore include epitopes with conserved homology across related pathogen types, because it is not always possible to include the antigens of all the individual types of a given pathogen species. The use of novel adjuvants with greater immunostimulatory properties can also contribute to improved overall vaccine cross-reactivity, as could the use of antigen delivery platforms. The growing body of evidence allows us to better understand the full impact of vaccines - beyond vaccine-type disease - which should be taken into consideration when assessing the full value of vaccination programmes.

Recent changes in the epidemiology of Neisseria meningitidis serogroup W across the world, current vaccination policy choices and possible future strategies

Invasive meningococcal disease (IMD) is a serious disease that is fatal in 5–15% and disabling in 12–20% of cases. The dynamic and unpredictable epidemiology is a particular challenge of IMD prevention. Although vaccination against meningococcal serogroups A (MenA), MenC and, more recently, MenB, are proving successful, other serogroups are emerging as major IMD causes. Recently, surges in MenW incidence occurred in South America, Europe, Australia and parts of sub-Saharan Africa, with hypervirulent strains being associated with severe IMD and higher fatality rates. This review describes global trends in MenW-IMD epidemiology over the last 5–10 years, with emphasis on the response of national/regional health authorities to increased MenW prevalence in impacted areas. Several countries (Argentina, Australia, Chile, the Netherlands and UK) have implemented reactive vaccination campaigns to reduce MenW-IMD, using MenACWY conjugate vaccines. Future vaccination programs should consider the evolving epidemiology of MenW-IMD and the most impacted age groups.

Whole genome sequencing of Neisseria meningitidis W isolates from the Czech Republic recovered in 1984-2017

Introduction

The study presents the analysis of whole genome sequence (WGS) data for Neisseria meningitidis serogroup W isolates recovered in the Czech Republic in 1984–2017 and their comparison with WGS data from other countries.

Material and methods

Thirty-one Czech N. meningitidis W isolates, 22 from invasive meningococcal disease (IMD) and nine from healthy carriers were analysed. The 33-year study period was divided into three periods: 1984–1999, 2000–2009, and 2010–2017.

Results

Most study isolates from IMD and healthy carriers were assigned to clonal complex cc22 (n = 10) in all study periods. The second leading clonal complex was cc865 (n = 8) presented by IMD (n = 7) and carriage (n = 1) isolates that emerged in the last study period, 2010–2017. The third clonal complex was cc11 (n = 4) including IMD isolates from the first (1984–1999) and third (2010–2017) study periods. The following clonal complex was cc174 (n = 3) presented by IMD isolates from the first two study periods, i.e. 1984–1999 and 2000–2009. One isolate of each cc41/44 and cc1136 originated from healthy carriers from the second study period, 2000–2009. The comparison of WGS data for N. meningitidis W isolates recovered in the Czech Republic in the study period 1984–2017 and for isolates from other countries recovered in the same period showed that clonal complex cc865, ST-3342 is unique to the Czech Republic since 2010. Moreover, the comparison shows that cc11 in the Czech Republic does not comprise novel hypervirulent lineages reported from both European and non-European countries. All 31 study isolates were assigned to Bexsero® Antigen Sequence Types (BAST), and seven of them were of newly described BASTs.

Conclusions

WGS analysis contributed considerably to a more detailed molecular characterization of N. meningitidis W isolates recovered in the Czech Republic over a 33-year period and allowed for a spatial and temporal comparison of these characteristics between isolates from the Czech Republic and other countries. The most interesting finding of this study is that eight of 31 Czech isolates of N. meningitidis W belong to clonal complex cc865, which is uncommon for serogroup W. In addition, the WGS data precised the base for the update of the recommendation for vaccination in the Czech Republic.