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

Evaluation of the World Health Organization Global Invasive Bacterial Vaccine-Preventable Disease (IB-VPD) Surveillance Network's Laboratory External Quality Assessment Programme, 2014-2019

Introduction. In 2009, the World Health Organization (WHO) established the Global Invasive Bacterial Vaccine Preventable Disease (IB-VPD) Surveillance Network (GISN) to monitor the global burden and aetiology of bacterial meningitis, pneumonia and sepsis caused by Haemophilus influenzae (Hi), Neisseria meningitidis (Nm) and Streptococcus pneumoniae (Sp).Hypothesis/Gap Statement. The GISN established an external quality assessment (EQA) programme for the characterization of Hi, Nm and Sp by culture and diagnostic PCR.Aim. To assess the performance of sentinel site laboratories (SSLs), national laboratories (NLs) and regional reference laboratories (RRLs) between 2014 and 2019 in the EQA programme.Methodology. Test samples consisted of bacterial smears for Gram-staining, viable isolates for identification and serotyping or serogrouping (ST/SG), plus simulated cerebrospinal fluid (CSF) samples for species detection and ST/SG by PCR. SSLs and NLs were only required to analyse the slides for Gram staining and identify the species of the live isolates. RRLs, and any SLs and NLs that had the additional laboratory capacity, were also required to ST/SG the viable isolates and analyse the simulated CSF samples.Results. Across the period, 69-112 SS/NL labs and eight or nine RRLs participated in the EQA exercise. Most participants correctly identified Nm and Sp in Gram-stained smears but were less successful with Hi and other species. SSLs/NLs identified the Hi, Nm and Sp cultures well and also submitted up to 56 % of Hi, 62 % of Nm and 33 % of Sp optional ST/SG results each year. There was an increasing trend in the proportion of correct results submitted over the 6 years for Nm and Sp. Some SSLs/NLs also performed the optional detection and ST/SG of the three organisms by PCR in simulated CSF from 2015 onwards; 89-100 % of the CSF samples were correctly identified and 76-93 % of Hi-, 90-100 % of Nm- and 75-100 % of Sp-positive samples were also correctly ST/SG across the distributions. The RRLs performed all parts of the EQA to a very high standard, with very few errors across all aspects of the EQA.Conclusion. The EQA has been an important tool in maintaining high standards of laboratory testing and building of laboratory capacity in the GISN.

Proceedings of the Expert Consensus Group meeting on meningococcal serogroup B disease burden and prevention in India

Meningococcal disease is highly transmissible, life-threatening and leaves significant sequelae in survivors. Every year, India, which has a plethora of risk factors for meningococcal disease, reports around 3000 endemic cases. However, the overall disease burden and serogroup distribution are unknown, creating a setting of general disease negligence and unawareness. Vaccination with quadrivalent meningococcal conjugate vaccine A, C, W, and Y is only recommended for high-risk children, and there is no overall guidance for meningococcal serogroup B (MenB) vaccination. MenB vaccines, which recently have been licensed in many countries but not in India, have significantly aided the fight against meningococcal disease. However, these MenB vaccines are not available in India. An Expert Consensus Group meeting was held with leading meningococcal disease experts to better understand the current disease epidemiology, particularly serogroup B, the prevalence gaps, and feasible ways to bridge them. The proceedings are presented in this paper.

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

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

Immunogenicity and safety of MenACWY-TT, a quadrivalent meningococcal tetanus toxoid conjugate vaccine recently licensed in the United States for individuals ≥2 years of age

Vaccination offers the best way to prevent invasive meningococcal disease (IMD). As demonstrated in countries with national immunization programs (NIPs) against IMD, meningococcal conjugate vaccines have contributed to significant declines in incidence. Since some meningococcal vaccines are associated with modest immunogenicity in infants, possible immunological interference upon concomitant administration with some pediatric vaccines, and administration errors resulting from improper reconstitution, opportunities for improvement exist. A quadrivalent conjugate vaccine, MenQuadfi® (Meningococcal [Serogroups A, C, Y, and W] Conjugate Vaccine; Sanofi, Swiftwater, Pennsylvania), was approved in 2020 for the prevention of IMD caused by meningococcal serogroups A, C, W, and Y in individuals ≥2 years of age in the United States. Five pivotal studies and one ancillary study supported approval in the United States; clinical trials in infants are ongoing. Data on the immunogenicity and safety of this vaccine are presented, and its potential value in clinical practice is discussed.

Preventing invasive meningococcal disease in early infancy

This review considers the pathogenesis, diagnosis, and epidemiology of invasive meningococcal disease in infants, to examine and critique meningococcal disease prevention in this population through vaccination. High rates of meningococcal disease and poor outcomes, particularly for very young infants, highlight the importance of meningococcal vaccination in early infancy. Although effective and safe meningococcal vaccines are available for use from 6 weeks of age, they are not recommended globally. Emerging real-world data from the increased incorporation of these vaccines within immunization programs inform recommendations regarding effectiveness, appropriate vaccination schedule, possible long-term safety effects, and persistence of antibody responses. Importantly, to protect infants from IMD, national vaccination recommendations should be consistent with available data regarding vaccine safety, effectiveness, and disease risk.

Comparing the meningococcal serogroup C immune response elicited by a tetanus toxoid conjugate quadrivalent meningococcal vaccine (MenACYW-TT) versus a quadrivalent or monovalent C tetanus toxoid conjugate meningococcal vaccine in healthy meningococcal vaccine-naïve toddlers: A randomised, controlled trial

MenACYW-TT (MenQuadfi®) is a quadrivalent meningococcal tetanus toxoid conjugate vaccine licensed in Europe for use in individuals ≥12 months. This study assessed whether serogroup C immune responses with MenACYW-TT were at least non-inferior, or superior, to those of quadrivalent meningococcal ACWY (MCV4-TT; Nimenrix®) and monovalent meningococcal C (MenC-TT; NeisVac-C®) vaccines in toddlers (12–23 months). In this modified, double-blind Phase III study (NCT03890367), 701 toddlers received one dose of MenACYW-TT (n = 230), MCV4-TT (n = 232) or MenC-TT (n = 239). Serum bactericidal assays with human (hSBA) and baby rabbit (rSBA) complement were used to measure anti-meningococcal serogroup C antibodies at baseline and 30 days post-vaccination. A sequential statistical approach was used for primary and secondary objectives. For the primary objectives, superiority of serogroup C was assessed in terms of hSBA seroprotection rates (defined as titers ≥1:8) and GMTs for MenACYW-TT compared to MCV4-TT, and rSBA GMTs compared to MenC-TT. The safety of all vaccines within 30 days post-vaccination was described. When administered as a single dose to meningococcal vaccine-naïve healthy toddlers the superiority of the MenACYW-TT serogroup C immune response versus MCV4-TT was demonstrated for hSBA GMTs (ratio 16.3 [12.7–21.0]) and seroprotection (difference 10.43% [5.68–16.20]); and versus MenC-TT in terms of rSBA GMTs (ratio 1.32 [1.06–1.64]). The safety profiles of a single dose of MenACYW-TT, MCV4-TT and MenC-TT were similar. In meningococcal vaccine-naïve toddlers, MenACYW-TT induced superior immune responses to serogroup C versus MCV4-TT in terms of hSBA seroprotection and GMTs and versus MenC-TT in terms of rSBA GMTs.

Invasive meningococcal disease in Malaysia, Philippines, Thailand, and Vietnam: An Asia-Pacific expert group perspective on current epidemiology and vaccination policies

Invasive meningococcal disease (IMD) imposes a significant burden on the global community due to its high case fatality rate (4-20%) and the risk of long-term sequelae for one in five survivors. An expert group meeting was held to discuss the epidemiology of IMD and immunization policies in Malaysia, Philippines, Thailand, and Vietnam. Most of these countries do not include meningococcal immunization in their routine vaccination programs, except for high-risk groups such as immunocompromised people and pilgrims. It is difficult to estimate the epidemiology of IMD in the highly diverse Asia-Pacific region, but available evidence indicate serogroup B is increasingly dominant. Disease surveillance systems differ by country. IMD is not a notifiable disease in some of them. Without an adequate surveillance system in the region, the risk and the burden of IMD might well be underestimated. With the availability of new combined meningococcal vaccines and the World Health Organization roadmap to defeat bacterial meningitis by 2030, a better understanding of the epidemiology of IMD in the Asia-Pacific region is needed.

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

INTRODUCTION

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

AREAS COVERED

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

EXPERT OPINION

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

Genetic Features of a Representative Panel of 110 Meningococcal B Isolates to Assess the Efficacy of Meningococcal B Vaccines

Predictions of vaccine efficacy against Neisseria meningitidis serogroup B (NmB) disease are hindered by antigenic variability, limiting the representativeness of individual NmB isolates. A qualitative human serum bactericidal assay using endogenous complements of individual subjects (enc-hSBA) enables large panels of NmB isolates to be tested. A 110-isolate panel was randomly selected from 442 invasive NmB isolates from United States cases reported to the Centers for Disease Control (CDC) from 2000 to 2008. Typing analyses confirmed the 110-isolate panel is representative of the 442 isolates. The genetic features of the 110-isolate panel were compared against over 4,200 invasive NmB isolates collected from 2000 to 2018 in the United States, Australia, Canada, and nine European countries. Clonal complexes in the 110-isolate panel are also present in each geographical region; cumulative percentages show that these account for around 81% of the clonal complexes found in NmB isolates in other panels. For the antigens (fHbp, NHBA, PorA1.4, NadA) included in the currently licensed meningococcal serogroup B (MenB) vaccines, specifically considering the presence of at least one antigen with a matched genotype, the 110-isolate panel represents approximately 89% of the NmB isolates circulating worldwide, ranging from 87% for the European isolates to 95% and 97% for NmB isolates in the United States and Australia, respectively. The 110-isolate panel includes the most prevalent clonal complexes and genetic variants of MenB vaccine antigens found in a multinational collection of invasive NmB isolates. This panel is useful for assessing the efficacy of MenB vaccines in clinical trials worldwide.

IMPORTANCENeisseria meningitidis serogroup B (NmB) is a major cause of invasive meningococcal disease (IMD). Predicting the effectiveness of vaccines against NmB is difficult because NmB is an uncommon disease and because antigens targeted by meningococcal serogroup B (MenB) vaccines have highly variable genetic features and expression levels. Therefore, a large number of NmB isolates from different regions would need to be tested to comprehensively assess vaccine effectiveness. We examined a panel of 110 isolates obtained from NmB IMD cases in the United States and compared the genetic features of this panel with those of panels from different countries around the world. We found the 110-isolate panel included the most common clonal complexes and genetic variants of MenB vaccine antigens that exist in the global collections of invasive NmB isolates. This confirms the value of the NmB 110-isolate panel in understanding the effectiveness of MenB vaccines in clinical trials worldwide.

Metagenomic data from cerebrospinal fluid permits tracing the origin and spread of Neisseria meningitidis CC4821 in China

Metagenomic next-generation sequencing (mNGS) is useful for difficult to cultivate pathogens. Here, we use cerebrospinal fluid mNGS to diagnose invasive meningococcal disease. The complete genome sequences of Neisseria meningitidis were assembled using N. meningitidis of ST4821-serotype C isolated from four patients. To investigate the phylogeny, 165 CC4821 N. meningitidis genomes from 1972 to 2017 were also included. The core genome accumulated variation at a rate of 4.84×10⁻⁸ substitutions/nucleotide site/year. CC4821 differentiated into four sub-lineages during evolution (A, B, C, and D). While evolving from sub-lineage A (early stage) to sub-lineage D (late stage), the ST and CC4821 serotype converged into the ST4821-serotype C clone. Most strains of sub-lineage D were isolated from invasive meningococcal disease, with increasing resistance to quinolones. Phylogeographic analysis suggests that CC4821 has spread across 14 countries. Thus, the selective pressure of quinolones may cause CC4821 to converge evolutionarily, making it more invasive and facilitating its spread.

Metagenomic data from cerebrospinal fluid was used to genotype Neisseria meningitidis in patients with invasive meningococcal disease and trace the origin of the pathobiont, providing a phylogeographic analysis of the strain’s evolution in China and its global spread.

Sequelae at Hospital Discharge in 61 Children With Invasive Meningococcal Disease, Chile, 2009-2019

BACKGROUND

Invasive meningococcal disease (IMD) is an unpredictable and severe infection caused by Neisseria meningitidis . Its case fatality rate could vary from 9.7% to 26% and up to 36% of survivors may experience long-term sequelae, representing a challenge for public health.

AIMED

To describe the sequelae at hospital discharge caused by IMD in children between years 2009-2019.

METHODS

Cross-sectional study performed in 2 pediatric hospitals. Patients with microbiologically confirmed diagnosis of IMD from 2009 to 2019 were included. Bivariate and logistic regression analysis were performed.

RESULTS

The records of 61 patients were reviewed and included. Sixty-seven percent were male, median age 9 months (interquartile range 4-27), 72% were admitted to intensive care unit. Thirty-seven (60.5%) had at least 1 sequela (75% and 37% in patients with or without meningitis, respectively). The most frequents sequelae were neurological 72%, hearing loss 32%, and osteoarticular 24%. Significant differences were found comparing patients with and without sequelae: drowsiness 67.6% versus 41.7% ( P = 0.04), irritability 67.6% versus 25% ( P = 0.01), meningeal signs 62.2% versus 29.2% ( P = 0.01). In logistic regression analysis, postdischarge follow-up had OR 21.25 (95% confidence intervals [CI]: 4.93-91.44), irritability had OR 8.53 (95% CI: 1.64-44.12), meningeal signs had OR 8.21 (95% CI: 0.71-94.05), invasive mechanical ventilation had OR 8.23 (95% CI: 0.78-85.95), meningitis plus meningococcemia OR 1.70 (95% CI: 0.18-15.67) to have sequelae, while children with meningococcemia and vomiting had a OR 0.04 (95% CI: 0.00-0.36) and OR 0.27 (95% CI: 0.03-2.14), respectively. N. meningitidis serogroup W (MenW) was isolated in 54.1% (33/61), and N. meningitidis serogroup B (MenB) in 31.1% (19/61) of cases. A significant difference was found in osteoarticular sequelae ( P = 0.05) between MenB and MenW. There was a decrease in cases after the meningococcal conjugate vaccine against serogroups A, C, W and Y was implemented (2015-2019).

CONCLUSIONS

IMD remains as a public health concern. A high rate of sequelae was found in pediatric patients in our series, even in the clinical manifestations other than meningitis. Neurological sequelae were the most prevalent. Multidisciplinary follow-up protocols to reduce long-term impact must be urgently established to assess all children with IMD.

An analysis of Neisseria meningitidis strains causing meningococcal septic arthritis in England, and Wales: 2010-2020

OBJECTIVES

To analyse clinical meningococcal strains associated with meningococcal septic arthritis cases in England and Wales, and to identify associations between patient age, the synovial joint affected and strain characteristics.

METHODS

IMD cases confirmed by the Meningococcal Reference Unit (UK Health Security Agency) between January 2010 and December 2020 were included in the analysis. Septic arthritis cases were defined as those featuring detection and/or isolation of N. meningitidis from an articular site. Capsular grouping was performed by serology on clinical isolates and/or real-time PCR on clinical samples.

RESULTS

We identified 162 cases of meningococcal septic arthritis, representing 2% of all invasive meningococcal disease cases during the study period. The knee and the hip were the most commonly affected joints, with the former significantly more frequent in adults and the latter seen more commonly in children and adolescents. Group B strains were between 2 and 6 times less likely to cause septic arthritis in relation to groups W, C and Y strains.

CONCLUSIONS

Meningococcal septic arthritis remains a rare manifestation of invasive meningococcal disease. Strain and age associations identified in this study remain unexplained. Future analyses including clinical case information may help to explain these interesting findings.

Neisseria Meningitidis Serogroup Z–Induced Meningitis: The First Case from Turkey

Neisseria meningitidis is a significant worldwide cause of bacterial meningitis and sepsis. High case-fatality rates and severe complications in survivors can occur. We present a 1-month 23-day-old case diagnosed with meningococcal meningitis and sepsis, in which serogroup Z of N. meningitidis was isolated from cerebrospinal fluid and blood cultures and treated with ceftriaxone for 7 days. Our patient is the first case of N. meningitidis serogroup Z–induced invasive meningococcal infection in Turkey. N. meningitidis serogroup Z is not included in the current meningococcal vaccines. It is concerning that a nonvaccine serogroup caused this invasive meningococcal disease and that even if the vaccine would cover this serogroup, it has happened before the usual age of administration. Therefore, meningococcal disease surveillance should continue, and an effective prevention and control strategy for nonvaccine serogroups should be implemented.

Missed Opportunities? A retrospective study into adults hospitalized with invasive infection from airway pathogens

Background

Invasive disease caused by airway pathogens, including Streptococcus pneumoniae, Haemophilus influenzae, Neisseria meningitidis, and Moraxella catarrhalis, has high morbidity and mortality worldwide, with immunodeficiency being a known association with recurrent disease. The study aimed to describe the frequency of known immunodeficiency and predisposing factors in adult patients presenting with invasive infections and determine the frequency of screening for and detection of immunodeficiency.

Methods

A retrospective analysis was conducted at a large tertiary Australian health service, comprising multiple centers. Patients aged 18 years or older, in whom the above pathogens were isolated from sterile sites, were included as identified through a microbiology database, between 2015 and 2020. Using electronic medical records, patient demographics, medical history, outcomes of admission, and pathology results were captured and reviewed to address the aims.

Results

In 252 patients, S pneumoniae was the most common culprit, isolated in 73% (185/252), compared to 14.3% (36/252) and 11.5% (29/252) of infections caused by H influenzae and N meningitidis, respectively. Known diagnoses of secondary immunodeficiency were common (31% of patients). Of those presenting with invasive pneumococcal disease, 78% had at least 1 predisposing condition, though only 9 patients (6%) had previously received pneumococcal vaccination. Despite poor screening for immunodeficiency, 12 new diagnoses were made. While the commonest immunodeficiency was secondary, due to hematological and solid organ malignancies, 3 new primary immunodeficiency diagnoses were made.

Conclusions

Immunodeficiency is common in this patient population. Screening should be undertaken to ensure timely diagnosis and treatment of the underlying condition to avoid future morbidity and mortality.

Prevalence of Neisseria meningitidis serogroups in invasive meningococcal disease in China, 2010 - 2020: a systematic review and meta-analysis

Invasive meningococcal disease (IMD) caused by Neisseria meningitidis (Nm) continues to be a global public health concern. Understanding the prevalence of Nm serogroups in IMD is critical for developing strategies for meningococcal vaccination. We used the keywords “cerebrospinal meningitis”, “meningococcal”, “Neisseria meningitidis’’, “meningococcal meningitis”, “serogroup’’ and “China’’ to search five databases, including PubMed, CNKI, CBM (Chinese BioMedical Literature Database), WanFang and VIP from 2010 to 2020. The age distributions, proportions of Nm serogroups and serogroup changes in IMD were analyzed. A total of 14 studies were included according to PRISMA guidelines. In China, from 2010 to 2020, the highest proportion of Nm in IMD was NmC, with 49.7% (95% CI: 35.8%–63.5%), followed by NmB with 30.2% (95%CI:17.3%–43.0%) and NmW with 23.8% (95%CI: 7.0–40.7%). Before 2014, NmC was the major circulating serogroup, with 59.6% (95% CI: 43.8%-75.4%), followed by NmW with 24.4% (95% CI: 5.9%–42.9%). After 2015, IMD cases caused by NmB were increasing, the proportion of NmB reached to 52.4% (95% CI: 31.8%–73.1%). The age groups of children from 0 to 5 years and from 6 to 10 years represented, respectively, 29.6% (95% CI: 16.8%–42.4%) and 28.9% (95% CI: 12.1%–45.8%) of all IMD cases were reported. In China, NmB, NmC and NmW were the major serogroups causing IMD between 2010 and 2020. Since 2015, the proportion of NmB increased rapidly. The current serogroup distribution in China highlights the need of replacing the meningococcal polysaccharide vaccines that are being used in the National Immunization Program with more appropriate vaccines.

Range of invasive meningococcal disease sequelae and health economic application - a systematic and clinical review

Background

Invasive meningococcal disease (IMD) is uncommon, life-threatening, with many diverse sequelae. The aims were to: 1) comprehensively characterise the sequelae; 2) have a systematic application for sequelae impact in economic evaluation (EE).

Methods

Sequelae categorised as physical/neurological or psychological/behavioural were identified from a systematic review of IMD observational studies (OS) and EEs in high-income countries (published 2001–2020). A comprehensive map and EE-relevant list, respectively, included physical/neurological sequelae reported in ≥2OS and ≥ 2OS + 2EE (≥1OS and ≥ 1OS + 1EE for psychological/behavioural). Sequelae proportions were selected from the highest quality studies reporting most sequelae. Three medical experts independently evaluated the clinical impact of findings.

Results

Sixty-Six OS and 34 EE reported IMD sequelae. The comprehensive map included 44 sequelae (30 physical/neurological, 14 psychological/behavioural), of which 18 (14 physical/neurological and 4 psychological/behavioural) were EE-relevant. Experts validated the study and identified gaps due to limited evidence, underreporting of psychological/behavioural sequelae in survivors/their families, and occurrence of multiple sequelae in the acute phase and long-term.

Conclusions

The considerable burden of IMD sequelae on survivors and their families is potentially underestimated in EE, due to underreporting and poorly-defined subtle sequelae. When assessing IMD burden and potential interventions e.g., vaccination, sequelae range and duration, underreporting, and indirect burden on dependents should be considered.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12889-022-13342-2.

Invasive meningococcal disease survivors frequently suffer from variable sequelae.

A broad sequelae map plus those relevant to economic evaluation (EE) were defined.

Forty-four sequelae were selected: 30 physical/neurological and 14 psychological/behavioural.

Eighteen EE-relevant sequelae included 14 physical/neurological and 4 psychological/behavioural

Underreporting, family impact and multiple sequelae cases were critical gaps.

A video summary linked to this article can be found on Figshare: 10.6084/m9.figshare.19753840.

Meningococcal Disease and Immunization Activities in Hajj and Umrah Pilgrimage: a review

Invasive meningococcal disease (IMD) outbreaks associated with Hajj and Umrah pilgrimage events in the Kingdom of Saudi Arabia (KSA) are well recognized. Past outbreaks have been associated with substantial intercontinental spread of specific Neisseria meningitidis serogroups. The emergence of meningococcal serogroup W (MenW) was a global concern following the 2000/2001 Hajj outbreaks. Broader compulsory meningococcal serogroups A, C, W and Y (MenACWY) immunization strategies for pilgrims were introduced in response to these events and led to substantial declines in IMD cases associated with these mass gatherings. However, there remains potential for future outbreaks either within KSA during the Hajj or in local populations via pilgrim meningococcal transmission on their return. While the annual Hajj involves pilgrims from over 185 countries, two-thirds of these arrive from 13 countries, chiefly from across South-East Asia, the Middle East and North African (MENA) regions; for which we review the relevant epidemiology of IMD and meningococcal carriage. While disease surveillance is limited and data are often lacking, MenB is an important serogroup associated with IMD and carriage in a number of countries. Available literature suggests that most pilgrims receive polysaccharide MenACWY vaccines (which do not impact carriage and onward transmission) and incomplete compliance with visa/entry immunization regulations is reported. Existing preventative approaches for visiting pilgrims require continued oversight. More complete compliance and switching to the conjugated MenACWY vaccine can provide more robust and broader protection for pilgrims. Additional immunization options could also be considered.

The epidemiology and outcomes of central nervous system infections in Far North Queensland, tropical Australia; 2000-2019

Background

The epidemiology of central nervous system (CNS) infections in tropical Australia is incompletely defined.

Methods

A retrospective study of all individuals in Far North Queensland, tropical Australia, who were diagnosed with a CNS infection between January 1, 2000, and December 31, 2019. The microbiological aetiology of the infection was correlated with patients’ demographic characteristics and their clinical course.

Results

There were 725 cases of CNS infection during the study period, meningitis (77.4%) was the most common, followed by brain abscess (11.6%), encephalitis (9.9%) and spinal infection (1.1%). Infants (24.3%, p<0.0001) and Aboriginal and Torres Strait Islander Australians (175/666 local residents, 26.3%, p<0.0001) were over-represented in the cohort.

A pathogen was identified in 513 cases (70.8%); this was viral in 299 (41.2%), bacterial in 175 (24.1%) and fungal in 35 (4.8%). Cryptococcal meningitis (24 cases) was diagnosed as frequently as pneumococcal meningitis (24 cases). There were only 2 CNS infections with a S. pneumoniae serotype in the 13-valent pneumococcal vaccine after its addition to the National Immunisation schedule in 2011. Tropical pathogens–including Cryptococcus species (9/84, 11%), Mycobacterium tuberculosis (7/84, 8%) and Burkholderia pseudomallei (5/84, 6%)–were among the most common causes of brain abscess. However, arboviral CNS infections were rare, with only one locally acquired case—a dengue infection in 2009—diagnosed in the entire study period. Intensive Care Unit admission was necessary in 14.3%; the overall case fatality rate was 4.4%.

Conclusion

Tropical pathogens cause CNS infections as commonly as traditional bacterial pathogens in this region of tropical Australia. However, despite being highlighted in the national consensus guidelines, arboviruses were identified very rarely. Prompt access to sophisticated diagnostic and supportive care in Australia’s well-resourced public health system is likely to have contributed to the cohort’s low case-fatality rate.

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.

Changes in Invasive Neisseria meningitidis and Haemophilus influenzae Infections in France during the COVID-19 Pandemic

BackgroundSince the appearance of COVID-19 in January 2020, invasive bacterial infections have decreased significantly worldwide. However, alterations in age and sex distributions, clinical forms, phenotypes, and genotypes of isolates have not been analyzed. Our goal is to present and discuss these data considering the current COVID-19 pandemic situation. Methods: The data of the national reference center for meningococci and Haemophilus influenzae in France were mined to examine the above aspects of invasive bacterial infection before (2018−2019) and after (2020−2021) the COVID-19 pandemic. Detailed epidemiological, clinical, and microbiological data were collected, and whole genome sequencing was carried out on meningococcal isolates (n = 1466). Results: In addition to the overall decline in the number of cases, various changes in age, sex, and phenotypes of isolates were also noted. As for N. meningitidis, more cases were observed in adults, as well as more invasive pneumopathies. Furthermore, fewer hyperinvasive meningococcal genotypes have circulated since COVID-19 emerged. The situation has been different for H. influenzae, as the number of invasive cases among adults decreased due to a reduction in non-typeable isolates. In contrast, cases due to serotypeable isolates, particularly serotypes a and b, increased in children <5 years-old. Conclusions: It is possible that measures implemented to stop COVID-19 may have reduced the circulation of N. meningitidis and H. influenzae isolates, but to a variable extent. This may be due to differences in circulation between these two species according to age groups. Vaccination schedules against these two species may have also influenced the evolution of these invasive bacterial infections since the emergence of the COVID-19 pandemic.

Preclinical development of the quadrivalent meningococcal (ACYW) tetanus toxoid conjugate vaccine, MenQuadfi®

Bacterial capsular polysaccharide vaccines are generally poorly immunogenic in infants and older adults. The immunogenicity of capsular polysaccharide vaccines can be improved by conjugating them to immunogenic carrier proteins. One of the most recently licensed conjugate vaccines is the quadrivalent meningococcal vaccine with serogroups A, C, Y, and W conjugated to a tetanus toxoid protein carrier (MenACYW-TT; MenQuadfi, Sanofi Pasteur, Swiftwater, PA, USA). MenACYW-TT was developed to induce optimal immune responses against each of the meningococcal serogroups A, C, W, and Y, and across all age groups, especially infants and older adults (those aged ≥ 50 years). Here, we detail the early iterative vaccine development approach taken, whereby many different ‘small-scale’ conjugate vaccine candidates were prepared and examined for immunogenicity in a mouse model to identify the most immunogenic vaccine. Additional insights from phase I clinical studies informed further optimization of the vaccine candidates by tailoring their conjugation parameter attributes for the optimal immune response in humans. The parameters studied included: different carrier proteins [PR]; polysaccharide [PS] sizes; conjugation chemistries [linker vs. no-linker; lattice vs. neoglycoprotein; activation/derivatization levels]; conjugate size; PS:PR loading ratio; percent free PS; percent free PR; and O-acetylation content. The lead quadrivalent conjugate vaccine (polysaccharides of > 50 kDa size conjugated to TT at a high PS:PR ratio via reductive amination for serogroups C, W and Y, and carbonyldiimidazole/adipic acid dihydrazide linker chemistry for serogroup A) empirically identified from the extensive preclinical studies, was ultimately confirmed by the robust antibody responses observed in all age groups in the various clinical studies, including in the most challenging infant and older adult age groups, and subsequently led to the licensed formulation.

Impact of COVID-19 pandemic on vaccination against meningococcal C infection in Brazil

Objective

Analyzing the impact of COVID-19 pandemic on meningococcal C conjugate vaccination in Brazil.

Methods

Ecological study, based on interrupted time series, carried out with data collected through the Information System of the National Immunization Program (IS-NIP). Collected data refer to the number of meningococcal C conjugate vaccine doses administered from March 2019 to December 2020.

Results

In total, 14,832,054 meningococcal C conjugate vaccine doses were administered throughout the investigated period; 66.30% of them, from March 2019 to February 2020 and 33.70%, from March to December 2020. Statistically significant steps were observed, i.e., the COVID-19 pandemic had negative impact on the number of MenC vaccine doses administered in the North and South regions (26,98% and 41.47%, respectively) and in the eleven Brazilian States.

Conclusion

The current study has shown that the COVID-19 pandemic had negative impact on the number of MenC vaccine doses administered in the Northern and Southern Brazil, and in eleven Brazilian states. Among all challenges experienced during the COVID-19 pandemic, one finds reduced MenC vaccine coverage, which, consequently, may lead to increased meningococcal infection rates in Brazil.

Gene polymorphisms of TLR10: effects on bacterial meningitis outcomes in Angolan children

This study examined whether gene polymorphisms for toll-like receptor 10 (TLR10) associated with the susceptibility to and outcomes of bacterial meningitis (BM) in Angolan children. The study cohort consisted of 190 BM patients and the determination of ten single-nucleotide polymorphisms (SNPs) by Sanger sequencing. Patients with BM caused by Streptococcus pneumoniae who carried the following variants of TLR10 SNPs exhibited an increased risk of coexisting pneumonia: rs10004195 (T > A) (p = 0.025), rs10856837 (G > A) (p = 0.018) or rs11096956 (G > T) (p = 0.010). Yet, TLR10 SNPs rs11466652 (A > G), rs10856837 (G > A) and rs11096956 (G > T) influenced the protein levels in the cerebrospinal fluid (CSF). Moreover, compared with the wild type, patients with pneumococcal meningitis carrying a variant genotype of TLR10 SNP rs11466648 (A > G) exhibited an increased risk of developing blindness (p = 0.025), whereas patients with TLR10 SNP rs10004195 (T > A) exhibited a lower risk of convulsions at admission (p = 0.039) and a lower risk of altered consciousness (p = 0.029). This study suggests a relationship exists between coexisting pneumonia, protein levels in CSF, blindness, convulsions and an altered consciousness with genetic variations of TLR10 in BM in Angolan children.

Meningococcal Disease in Pediatric Age: A Focus on Epidemiology and Prevention

Meningococcal disease is caused by Neisseria meningitidis; 13 serogroups have been identified and differentiated from each other through their capsular polysaccharide. Serotypes A, B, C, W, X, and Y are responsible for nearly all infections worldwide. The most common clinical manifestations are meningitis and invasive meningococcal disease, both characterized by high mortality and long-term sequelae. The infection rate is higher in children younger than 1 year and in adolescents, who are frequently asymptomatic carriers. Vaccination is the most effective method of preventing infection and transmission. Currently, both monovalent meningococcal vaccines (against A, B, and C serotypes) and quadrivalent meningococcal vaccines (against serogroups ACYW) are available and recommended according to local epidemiology. The purpose of this article is to describe the meningococcal vaccines and to identify instruments that are useful for reducing transmission and implementing the vaccination coverage. This aim could be reached by switching from the monovalent to the quadrivalent vaccine in the first year of life, increasing vaccine promotion against ACYW serotypes among adolescents, and extending the free offer of the anti-meningococcal B vaccine to teens, co-administering it with others proposed in the same age group. Greater awareness of the severity of the disease and increased health education through web and social networks could represent the best strategies for promoting adhesion and active participation in the vaccination campaign. Finally, the development of a licensed universal meningococcal vaccine should be another important objective.

Risk Factors for Contracting Invasive Meningococcal Disease and Related Mortality: A Systematic Literature Review and Meta-analysis

OBJECTIVES

To describe risk factors (RFs) and quantify their effects in invasive meningococcal disease (IMD) and associated mortality across all age groups based on the available published literature.

METHODS

A systematic literature review (SLR) was conducted via MEDLINE® and Embase. Study selection, data extraction, and quality assessment were performed by two independent reviewers. Associations between RFs and outcomes were quantified via a meta-analysis (MA).

RESULTS

Seventy-four studies (date range 1950 - 2018) were included in the SLR. Statistically significant RFs for contracting IMD identified from the SLR (within-study) included previous IMD infection and young age (0 - 4 years). MA indicated that significant RFs for contracting IMD (11 studies) were: HIV-positive status, passive smoke exposure, and crowded living space. In the MA for IMD-related mortality risk (11 studies), age 25 - 45 years (vs. 0 - 5 years) and serogroup C (vs. serogroup B) were significantly associated with increased risk.

CONCLUSIONS

Previous findings of higher risk for IMD contraction with smoke exposure and crowded living conditions in children/adolescents have been extended by this SLR/MA to all age groups. We provide strong evidence for higher risk of IMD in HIV-positive individuals, and confirm previous findings of higher IMD-related mortality risk in adults aged 25 - 45.

Epidemiology of invasive meningococcal disease and sequelae in the United Kingdom during the period 2008 to 2017 - a secondary database analysis

Background

Invasive meningococcal disease (IMD) causes high fatality in untreated patients alongside long-term sequelae in 20% survivors. For a comprehensive assessment of epidemiology, an analysis of these sequelae is required. This study aims to investigate the epidemiology of disease between 2008 and 2017 including a description of the sequelae, through the analysis of data collected from the UK Clinical Practice Research Datalink (CPRD) linked with data from the Hospital Episode Statistics (HES), and Office for National Statistics (ONS) mortality registry data.

Methods

This was a 10-year retrospective observational cohort study designed to describe the incidence, case-fatality rate (CFR) and occurrence of sequelae due to meningococcal disease, in the UK between 2007 and 2017 using data from the UK CPRD-HES-ONS. Cases were identified and matched on age, gender, date of diagnosis of IMD and followed-up-time with a control group without IMD. Demographics, clinical characteristics, mortality, and IMD-related sequelae were examined for IMD cases and compared with matched controls for a more comprehensive assessment.

Results

The study analysed 640 IMD patients with majority of the cases diagnosed (76.9%) in a hospital setting. Age-group analysis showed a decrease in the incidence rate of IMD in patients aged <1 year (30.4 – 7.5%) and an increase in those >50 years (10.4 – 27.8%). CFR was slightly higher among females, toddlers, and adults >50 years. No significant change in CFR was observed over study period. Case-control study showed a higher number of IMD sequelae among cases compared to age- and gender-matched controls, especially in those ≥ 50 years.

Conclusion

The study showed that, despite a relatively low incidence rate, IMD is responsible for a high CFR, namely in older age groups and by a high number of IMD sequelae. The study showed that leveraging data from existing databases can be used to complement surveillance data in truly assessing the epidemiology of IMD. Despite the availability of routine vaccination programs, IMD still poses a significant burden in the healthcare system of the UK. Optimization of vaccination programs may be required to reduce the disease burden.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12889-022-12933-3.

Equity in vaccination policies to overcome social deprivation as a risk factor for invasive meningococcal disease

INTRODUCTION

Social deprivation is associated with poorer healthcare access. Vaccination is among the most effective public health interventions and achieving equity in vaccination access is vitally important. However, vaccines are often reimbursed by public funds only when recommended in national immunization programs (NIPs), which can increase inequity between high and low socioeconomic groups. Invasive meningococcal disease (IMD) is a serious vaccination-preventable disease. This review focuses on vaccination strategies against IMD designed to reduce inequity.

AREAS COVERED

We reviewed meningococcal epidemiology and current vaccination recommendations worldwide. We also reviewed studies demonstrating an association between social deprivation and risk of meningococcal disease, as well as studies demonstrating an impact of social deprivation on uptake of meningococcal vaccines. We discuss factors influencing inclusion of meningococcal vaccines in NIPs.

EXPERT OPINION

Incorporating meningococcal vaccines in NIPs is necessary to reduce inequity, but insufficient alone. Inclusion provides clear guidance to healthcare professionals and helps to ensure that vaccines are offered universally to all target groups. Beyond NIPs, cost of vaccination should be reimbursed especially for disadvantaged individuals. These approaches should help to achieve optimal protection against IMD, by increasing access and immunization rates, eventually reducing social inequities, and helping to protect those at greatest risk.

Whole genome sequencing of Neisseria meningitidis Y isolates collected in the Czech Republic in 1993-2018

Introduction

The study presents the analysis of whole genome sequencing (WGS) data for Neisseria meningitidis serogroup Y isolates collected in the Czech Republic and their comparison to other countries. The aim of the study was to determine whether there are lineages of N. meningitidis serogroup Y in the Czech Republic genetically related to foreign ones that have been causing an increase of the morbidity and the mortality of invasive meningococcal disease (IMD) world-wide recently.

Material and methods

The WGS data of 43 Czech N. meningitidis Y isolates, 35 from IMD and 8 from healthy carriers were analysed. Due to the potential of meningococcal B vaccines to induce protection against non-B serogroups, the coverage of Czech isolates of N. meningitidis Y by these vaccines was studied. The WGS data of Czech, European and non-European isolates of N. meningitidis serogroup Y were compared.

Results

WGS assigned 36 isolates of N. meningitidis Y to five clonal complexes: cc23, cc92, cc167, cc103, and cc174, while seven isolates remained unassigned to any clonal complexes (ccUA). Eighteen invasive isolates belonged to clonal complex cc23, which was detected throughout the studied years. The occurrence of cc23 was recorded in all age groups of IMD patients, with the highest found in those aged 15–19 years. On the phylogenetic network isolates of cc23 form a separate lineage, distinct from all other isolates of N. meningitidis Y. The remaining isolates were assigned to other clonal complexes and have very low relatedness to cc23 isolates and to each other. The comparison with foreign WGS data showed that within the main genetic lineages, which are defined by clonal complexes, Czech isolates of N. meningitidis Y, similar to European ones, mostly cluster together and form geographical sublineages.

Conclusions

WGS analysis showed the population of Czech N. meningitidis Y isolates as relatively heterogeneous, containing a large number of genetic lineages. The Czech isolates of N. meningitidis Y follow the trend observed for European isolates. Our result was one of the bases for updating the recommended vaccination strategy in the Czech Republic.

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.

Invasive meningococcal disease in Chile seven years after ACWY conjugate vaccine introduction

BACKGROUND

A serogroup W (MenW) outbreak in Chile prompted a meningococcal vaccination campaign using tetravalent meningococcal-conjugate vaccines (MCV-ACWY) in children since 2012, followed by its introduction into the National Immunization Program (NIP) in toddlers from 2014. Direct protection was observed, but no indirect effects in other age-groups were evidenced. The aim of this study was to describe invasive meningococcal disease (IMD) cases in Chile between 2009 and 2019, and its trend after the introduction of MCV-ACWYs.

METHODS

IMD cases, cumulative incidence per 100,000 inhabitants, CFR, and vaccination uptake were described. Data were obtained from the Public Health Institute and NIP.

RESULTS

Overall-IMD cases increased in 2009-2014 period, followed by a decline in 2015-2019, focused in infants, children <5 years and people ≥60 years. Serogroup B (MenB) and MenW alternate its predominance. Median overall incidence was 0.6/100,000, increasing from 0.6/100,000 in 2009 to 0.8/100,000 in 2014, later decreasing to 0.4/100,000 in 2019. Median incidences for MenB, serogroup C (MenC) and Y (MenY) were 0.25/100,000, <0.01/100,000 and <0.01/100,000, respectively. Median MenW incidence was 0.53/100,000, increasing from 0.01/100,000 in 2009 to 0.56/100,000 in 2014, followed by a constant decline to 0.12 in 2019. Infants, children <5 years and adults ≥60 years were affected the most, with median incidences of 9.7, 0.9 and 0.93, decreasing to 1.3, 0.1 and 0.1/100,000 in 2019, respectively. Median overall-CFR was 19%, 7.5% for MenB and 24.5% for MenW. Median MCV-ACWY uptake was 93% CONCLUSION: Overall-IMD, MenW cases and incidence declined since 2015 after the MCV-ACWY introduction, while MenB, MenC and MenY have been stable. MenW incidence declined in all age groups, including non-immunized infants and people >60 years. Further analysis and a longer period of observation are needed to have a more robust conclusion about this epidemiological trend. By 2019, CFR remains high.

A Mouse Immunogenicity Model for the Evaluation of Meningococcal Conjugate Vaccines

The identification of an appropriate animal model for use in the development of meningococcal vaccines has been a challenge as humans are the only natural host for Neisseria meningitidis. Small animal models have been developed and are widely used to study the efficacy or immunogenicity of vaccine formulations generated against various diseases. Here, we describe the development and optimization of a mouse model for assessing the immunogenicity of candidate tetravalent meningococcal polysaccharide (MenACYW-TT) protein conjugate vaccines. Three inbred (BALB/c [H-2d], C3H/HeN [H-2k], or C57BL/6 [H-2b]) and one outbred (ICR [H-2g7]) mouse strains were assessed using serial two-fold dose dilutions (from 2 µg to 0.03125 µg per dose of polysaccharide for each serogroup) of candidate meningococcal conjugate vaccines. Groups of 10 mice received two doses of the candidate vaccine 14 days apart with serum samples obtained 14 days after the last dose for the evaluation of serogroup-specific anti-polysaccharide IgG by ELISA and bactericidal antibody by serum bactericidal assay (SBA). C3H/HeN and ICR mice had a more dose-dependent antibody response to all four serogroups than BALB/c and C57Bl/6 mice. In general, ICR mice had the greatest antibody dose-response range (both anti-polysaccharide IgG and bactericidal antibodies) to all four serogroups and were chosen as the model of choice. The 0.25 µg per serogroup dose was chosen as optimal since this was in the dynamic range of the serogroup-specific dose-response curves in most of the mouse strains evaluated. We demonstrate that the optimized mouse immunogenicity model is sufficiently sensitive to differentiate between conjugated polysaccharides, against unconjugated free polysaccharides and, to degradation of the vaccine formulations. Following optimization, this optimized mouse immunogenicity model has been used to assess the impact of different conjugation chemistries on immunogenicity, and to screen and stratify various candidate meningococcal conjugate vaccines to identify those with the most desirable profile to progress to clinical trials.

Impact of meningococcal C conjugate vaccine on incidence of invasive meningococcal disease in an 18-year time-series in Brazil and in distinct Brazilian regions

OBJECTIVE

To evaluate the impact of meningococcal C conjugate (MCC) vaccine in Brazil.

METHODS

Ecological study assessing all invasive meningococcal disease (IMD) and meningococcal C disease (MenC) cases reported in all age groups, from 2001 to 2019. MCC was implemented in 2010. Data were collected on the DATASUS platform. Joinpoint regression was performed to assess the Annual Percent Change (APC) of the incidence rate.

RESULTS

IMD incidence decreased in all Brazilian regions from 2001 onwards, without apparent additional reduction attributable to MCC vaccine in the North, Northeast and South. The higher and statistically significant APC reduction in all age groups, in the North and South, and in children <5 years, in the Northeast, occurred between 2001-2011 (-15.4%), 2004-2012 (-14.4%), and 2001-2013 (-10.3%), respectively, before MCC vaccine implementation. Annual incidence of MenC in under 5 years significantly fell in the North (-6.8%; 2011-2018), Southeast (-40.6%; 2010-2015) and Midwest (-48.6%; 2010-2014), which may be attributable to MCC implementation.

CONCLUSION

IMD and MenC behaved differently after MCC vaccine implementation in Brazil during this 18-year time-series analysis. This suggests that the control of IMD should be based on multiple public health care measures and considered on a regional basis.

Overview of meningococcal epidemiology and national immunization programs in children and adolescents in 8 Western European countries

BACKGROUND

In Europe, meningococcal (Men) vaccines are available against 5 of the 6 serogroups responsible of nearly all cases of invasive meningococcal disease (IMD). Meningococcal vaccination has been introduced in the national immunization programs (NIPs) for children and adolescents of numerous European countries, but with no consistent strategy across countries.

OBJECTIVES

To describe IMD epidemiology, NIPs, and vaccination coverage rates (VCRs) in children and adolescents in 8 Western European countries.

METHODS

Epidemiological data (from 1999 to 2019), NIPs regarding meningococcal vaccination status, and VCRs were collected from the European Centre for Disease Prevention and Control (ECDC) and/or national websites.

RESULTS

MenB was the most common serogroup. In Belgium, Spain, France, the Netherlands, the United Kingdom (UK), and Portugal, incidence was greater for MenW than MenC. In 2019, MenB risk was covered in 2 countries (Italy, UK). MenC risk was covered in all countries, via MenC only (countries: N = 3), MenACWY only (N = 2), or MenC (infants/children) and MenACWY (adolescents) (N = 3) vaccination. VCRs were higher in children than adolescents.

CONCLUSION

Our study confirmed the diversity of NIPs, including in neighboring European countries with similar factors like economic resources and epidemiological risk, thus indicating that other factors underlie NIPs. Convergence toward a more common immunization program including MenACWY and MenB vaccination would promote equity and safe travel regarding infectious diseases for young people, and possibly improve the understanding of vaccination by patients and healthcare professionals.

Evolution of strain coverage by the multicomponent meningococcal serogroup B vaccine (4CMenB) in France

The 4CMenB, a protein-based vaccine, was licensed in Europe in 2013 against invasive meningococcal disease caused by serogroup B and is currently implemented in several countries although according to different national strategies. Isolate coverage estimation is required as vaccine-targeted antigens may vary among isolates over time. Several phenotypic and genotypic methods have been developed to predict strain coverage by scoring the expression and cross-reactivity of vaccine antigens using the Meningococcal Antigen Typing system (MATS), by the genetic correlation of alleles encoding these antigens and MATS expression data (gMATS) and by the Meningococcal Deduced Vaccine Antigen Reactivity (MenDeVAR). We applied these approaches on meningococcal B isolates in France and compared two epidemiological years, 2013-2014 and 2018-2019. A strong correlation was observed between MATS data that were generated for the year 2013-2014 and the gMATS data extracted from whole genome sequencing. gMATS and MenDeVAR were next used to compare the two years. Using gMATS, the overall coverage was 77.2% (lower limit (LL)-upper limit (UL) 66.7-87.7) and 70.7% (LL-UL 61.5-80.0) for the two years, respectively. The reduction in coverage between the two years is mainly driven by the reduction of alleles exactly matching the vaccine antigens. A high number of unpredictable isolates was observed using the MenDeVAR and was due to lack of MATS information for new or rare alleles in particular for the year 2018-2019. Our data underline the need of continuous surveillance of strain coverage and the importance of generating phenotypic MATS data to update the genetic approaches of prediction.

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

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

The epidemiology of meningococcal meningitis: multicenter, hospital-based surveillance of meningococcal meningitis in Iraq

•

Most bacterial meningitis cases in Iraq were due to N. meningitidis infections

•

Meningococcal meningitis was associated with young age, and with the winter

•

Incidence rates were highest in Karbala, and may be linked to mass gatherings there

•

The prevalent serogroups indicate a need for increased vaccination coverage in Iraq

Objectives

Outbreaks of Neisseria meningitidis have reached alarming levels due to the pathogen's ability to cause severe complications, presenting as meningitis or septicemia. Our study reports the results of the first wide-scale surveillance of meningococcal meningitis in Iraq.

Methods

The study included all consecutive cases of clinically suspected meningitis between June 2018 and May 2020 at 18 major hospitals around Iraq (n = 2314). Laboratory analysis of biological samples and real-time polymerase chain reaction tests were conducted to confirm bacterial etiology. Demographical and medical data were collected for statistical analysis.

Results

In total, 370 patients were confirmed to have bacterial meningitis (215 had N. meningitidis, 154 had Streptococcus pneumoniae, and one case had Haemophilus influenzae type b). The most common N. meningitidis serogroup was B (77.7%), followed by W (18.1%) and X (4.2%). The annual incidence rate of N. meningitidis per 100 000 population was 0.86, with the highest being in Karbala (1.52 per 100 000 population). Cases of meningococcal meningitis were more likely to occur in children younger than 15 (OR = 3.526), and in the winter (OR = 1.474).

Conclusions

Continuous surveillance of N. meningitidis is necessary in Iraq, and can only be achieved through improved detection methods. The incidence of meningococcal meningitis in Iraq warrants improved vaccination programs.

Invasive serogroup B meningococci in England following three years of 4CMenB vaccination - First real-world data

OBJECTIVES

In 2015 the UK became the first country to implement the meningococcal B (MenB) vaccine, 4CMenB, into the national infant program. 4CMenB is expected to cover meningococci expressing sufficient levels of cross-reactive proteins. This study presents clonal complex, 4CMenB antigen genotyping, and 4CMenB coverage data for all English invasive MenB isolates from 2014/15 (1 year pre-vaccine) through 2017/18 and compares data from vaccinated and unvaccinated ≤3 year olds.

METHODS

Vaccine coverage of all invasive MenB isolates from 2014/15 to 2017/18 (n = 784) was analysed using the Meningococcal Antigen Typing System. Genotyping utilised the Meningococcus Genome Library.

RESULTS

Among ≤3 year olds, proportionally fewer cases in vaccinees (1, 2 or 3 doses) were associated with well-covered strains e.g. cc41/44 (20.5% versus 36.4%; P<0.01) and antigens e.g. PorA P1.4 (7.2% versus 17.3%; P = 0.02) or fHbp variant 1 peptides (44.6% vs 69.1%; P<0.01). Conversely, proportionally more cases in vaccinees were associated with poorly-covered strains e.g. cc213 (22.9% versus 9.6%; P<0.01) and antigens e.g. variant 2 or 3 fHbp peptides (54.2% versus 30.9%; P<0.01).

CONCLUSIONS

4CMenB reduces disease due to strains with cross-reactive antigen variants. No increase in absolute numbers of cases due to poorly covered strains was observed in the study period.

Primary meningococcal septic arthritis associated with joint calcium oxalate crystals: A case report and review of the literature

Primary meningococcal septic arthritis (PMSA) is an extremely rare local infection by Neisseria meningitidis in the absence of meningitis or meningococcaemia syndrome. A 30-year-old healthy, immunocompetent man presented with arthralgia, fever, chest rash, and significant swelling of the right knee. On admission, a disseminated maculopapular and purpuric rash, oligoarthritis, neutrophilia, and elevated acute phase reactants were documented. Following arthrocentesis of the right knee, isolation of N. meningitidis and the presence of calcium oxalate crystals in the synovial fluid were reported. The diagnosis of PMSA was made. Histological analysis of the skin lesion showed leucocytoclastic vasculitis. He was treated with intravenous ceftriaxone plus open surgical drainage and ambulatory cefixime with adequate response. After 1 month, he presented resolution of the pathological process. We performed an extensive review of the literature, finding that the key elements supporting the diagnosis of PMSA are prodromal upper respiratory tract symptoms and skin involvement prior to or synchronous with the arthritis. Also, the most frequently involved joint is the knee. This report is the first case of a patient presenting with PMSA associated with calcium oxalate crystals in the synovial fluid. Herein, we discuss the most frequent clinical manifestations, the unusual histological features, the recommended treatment, and the reported prognosis of this rare entity.

Genomic surveillance of Neisseria meningitidis serogroup W in Portugal from 2003 to 2019

In recent years, a change in the epidemiology of meningococcal disease caused by Neisseria meningitidis serogroup W (MenW) has been observed worldwide, with the emergence of new sublineages associated with a higher rate of fatal cases. The present study intends to describe the epidemiology of invasive meningococcal disease (IMD) due to MenW in Portugal between 2003 and 2019, and to genetically characterize population structure. Despite MenW has a low incidence in Portugal, having almost disappeared from 2008 to 2015, since 2016, the number of MenW cases has been steadily increasing at a rate of ~ twofold per year, with more than 80% of the characterized isolates belonging to clonal complex 11 (cc11). Core-genome phylogeny of 25 Portuguese (PT) MenW isolates showed a strain clustering mainly either with the Original UK or the UK 2013 sublineages. Our study also reported for the first time the presence of distinct prophages with a notable overrepresentation of an ~ 32-35-kb PS_1-like prophage found in MenW cc11 genomes. The presence of the PS_1-like prophage in almost all 4723 cc11 genomes selected from Neisseria PubMLST database regardless of the capsular group they belong to suggests an ancestral acquisition of this mobile element prior to capsular switching events. Overall, by mimicking the scenario observed worldwide, this study reinforces the importance of a close monitoring of MenW disease, especially from cc11, in order to promptly adapt the vaccination plan for IMD control in Portugal. Moreover, future studies are needed to understand the putative contribution of prophages to fitness and virulence of PT MenW strains.

4CMenB vaccine and its role in preventing transmission and inducing herd immunity

INTRODUCTION

: Vaccination is the most effective method of protecting people from invasive meningococcal disease (IMD). Of all the capsular groups, B is the most common cause of invasive meningococcal disease in many parts of the world. Despite this, adolescent meningococcal B vaccine programs have not been implemented globally, partly due to the lack of evidence for herd immunity afforded by meningococcal B vaccines.

AREAS COVERED

This review aims to synthesise the available evidence on recombinant 4CMenB vaccines' ability to reduce pharyngeal carriage and therefore provide indirect (herd) immunity against IMD.

EXPERT OPINION

There is some evidence that the 4CMenB vaccine may induce cross-protection against non-B carriage of meningococci. However, the overall body of evidence does not support a clinically significant reduction in carriage of disease-associated or group B meningococci following 4CMenB vaccination. No additional cost-benefit from herd immunity effects should be included when modelling the cost-effectiveness of 4CMenB vaccine programs against group B IMD. 4CMenB immunisation programs should focus on direct (individual) protection for groups at greatest risk of meningococcal disease.

Future meningococcal B and combination vaccines being developed should consider the impact of the vaccine on carriage as part of their clinical evaluation.

The changing face of meningococcal infection

Menigococcal infection is caused by Neisseria meningitidis, a Gram negative diplococci. Invasive meningococcal disease (IMD) is caused by 6 capsular groups. The spectrum of infection is broad, with meningitis and meningococcal sepsis associated with a case fatality of between 4 and 20%. The main burden of disease is felt in the under 1's and this is where vaccination has been focused. Vaccination against MenC begun in 1999, with vaccines against Men ACWY and MenB added to the schedule in 2015. Over the last 1o years rates of IMD in the UK have fallen by over 50%. The impact of COVID-19 on cases has also been felt, with early data suggesting a significant drop in cases during the first wave in 2020. Despite the success of vaccination we need to remain vigilant. Clonal expansion of hypervirulent strains has been seen in epidemics and we have a significant proportion of the population who remain unvaccinated.

A new fully liquid presentation of MenACWY-CRM conjugate vaccine: Results from a multicentre, randomised, controlled, observer-blind study

BACKGROUND

The currently licensed quadrivalent MenACWY-CRM conjugate vaccine presentation consists of two vials (lyophilised MenA and liquid MenCWY) to be reconstituted before injection. A new fully liquid formulation in a single vial has been developed to further improve the vaccine presentation. Since the MenA structure is subject to hydrolytic degradation, this study was conducted to compare the immunogenicity and safety of the investigational MenACWY-CRM liquid vaccine with the licensed vaccine.

METHODS

In this multicentre, randomised, controlled, observer-blind, phase 2b study, 979 healthy adults were administered a single dose of MenACWY-CRM liquid presentation or the currently licensed MenACWY-CRM vaccine. MenA free saccharide generation was accelerated to approximately 30% in the liquid presentation and MenA polysaccharide O-acetylation was reduced to approximately 40%, according to a controlled procedure. Immunological non-inferiority of the MenACWY-CRM liquid to the licensed vaccine, as measured by human serum bactericidal assay (hSBA) geometric mean titres (GMTs) against MenA 1 month post-vaccination, was the primary study objective. Safety assessment was among the secondary objectives.

RESULTS

Immune responses against each serogroup were similar between the two vaccine groups and was non-inferior for MenA. Adjusted hSBA GMTs for MenA were 185.16 and 211.33 for the MenACWY-CRM liquid presentation and currently licensed vaccine presentation, respectively. The between-group ratio of hSBA GMTs for MenA was 0.88, with a two-sided 95% confidence interval lower limit of 0.64, greater than the prespecified non-inferiority margin of 0.5, thus meeting the primary study objective. Both vaccines were well tolerated. No serious adverse events were considered related to vaccination.

CONCLUSIONS

The levels of MenA free saccharide and polysaccharide O-acetylation did not affect the immunogenicity of the fully liquid presentation, which was demonstrated to be non-inferior to the immunogenicity of the currently licensed MenACWY-CRM vaccine against MenA. The immunogenicity, reactogenicity and safety profiles of the two vaccine presentations were similar.

Systematic review of invasive meningococcal disease epidemiology in the Eastern Mediterranean and North Africa region

BACKGROUND

Invasive meningococcal disease (IMD) represents a global health burden. However, its epidemiology in the Eastern Mediterranean (EM) and North Africa (NA) regions is currently not well understood. This review had four key objectives: to describe asymptomatic meningococcal carriage, IMD epidemiology (e.g. serogroup prevalence, case-fatality rates [CFRs]), IMD presentation and management (e.g. clinical diagnosis, antibiotic treatments) and economic impact and evaluation (including health technology assessment [HTA] recommendations) in EM and NA.

METHODS

A systematic literature search (MEDLINE and EMBASE) was conducted (January 2000 to February 2021). Search strings included meningococcal disease and the regions/countries of interest. Identified publications were screened sequentially by title/abstract, followed by screening of the full-text article; articles were also assessed on methodological quality. Literature reviews, genetic sequencing or diagnostic accuracy studies, or other non-pertinent publication type were excluded. An additional grey literature search (non-peer-reviewed sources; start date January 2000) was conducted to the end of April 2019.

RESULTS

Of the 1745 publications identified, 79 were eligible for the final analysis (n = 61 for EM and n = 19 for NA; one study was relevant to both). Asymptomatic meningococcal carriage rates were 0-33% in risk groups (e.g. military personnel, pilgrims) in EM (no data in NA). In terms of epidemiology, serogroups A, B and W were most prevalent in EM compared with serogroups B and C in NA. IMD incidence was 0-20.5/100,000 in EM and 0.1-3.75/100,000 in NA (reported by 7/15 countries in EM and 3/5 countries in NA). CFRs were heterogenous across the EM, ranging from 0 to 57.9%, but were generally lower than 50%. Limited NA data showed a CFR of 0-50%. Data were also limited in terms of IMD presentation and management, particularly relating to clinical diagnosis/antibiotic treatment. No economic evaluation or HTA studies were found.

CONCLUSIONS

High-risk groups remain a significant reservoir of asymptomatic meningococcal carriage. It is probable that inadequacies in national surveillance systems have contributed to the gaps identified. There is consequently a pressing need to improve national surveillance systems in order to estimate the true burden of IMD and guide appropriate prevention and control programmes in these regions.

Genome-wide association studies reveal the role of polymorphisms affecting factor H binding protein expression in host invasion by Neisseria meningitidis

Many invasive bacterial diseases are caused by organisms that are ordinarily harmless components of the human microbiome. Effective interventions against these microbes require an understanding of the processes whereby symbiotic or commensal relationships transition into pathology. Here, we describe bacterial genome-wide association studies (GWAS) of Neisseria meningitidis, a common commensal of the human respiratory tract that is nevertheless a leading cause of meningitis and sepsis. An initial GWAS discovered bacterial genetic variants, including single nucleotide polymorphisms (SNPs), associated with invasive meningococcal disease (IMD) versus carriage in several loci across the meningococcal genome, encoding antigens and other extracellular components, confirming the polygenic nature of the invasive phenotype. In particular, there was a significant peak of association around the fHbp locus, encoding factor H binding protein (fHbp), which promotes bacterial immune evasion of human complement by recruiting complement factor H (CFH) to the meningococcal surface. The association around fHbp with IMD was confirmed by a validation GWAS, and we found that the SNPs identified in the validation affected the 5' region of fHbp mRNA, altering secondary RNA structures, thereby increasing fHbp expression and enhancing bacterial escape from complement-mediated killing. This finding is consistent with the known link between complement deficiencies and CFH variation with human susceptibility to IMD. These observations demonstrate the importance of human and bacterial genetic variation across the fHbp:CFH interface in determining IMD susceptibility, the transition from carriage to disease.

Immunological non-inferiority of a new fully liquid presentation of the MenACWY-CRM vaccine to the licensed vaccine: results from a randomized, controlled, observer-blind study in adolescents and young adults

A fully liquid MenACWY-CRM vaccine presentation has been developed, modifying the meningococcal serogroup A (MenA) component from lyophilized to liquid. The safety and immunogenicity of the liquid presentation at the end of the intended shelf-life (aged for 24 or 30 months) were compared to the licensed lyophilized/liquid presentation. This multicenter, randomized (1:1), observer-blind, phase 2b study (NCT03433482) enrolled adolescents and young adults (age 10-40 years). In part 1, 844 participants received one dose of liquid presentation stored for approximately 24 months or licensed presentation. In part 2, 846 participants received one dose of liquid presentation stored for approximately 30 months or licensed presentation. After storage, the MenA free saccharide (FS) level was approximately 25% and O-acetylation was approximately 45%. The primary objective was to demonstrate non-inferiority of the liquid presentation to licensed presentation, as measured by human serum bactericidal assay (hSBA) geometric mean titers (GMTs) against MenA, 1-month post-vaccination. Immune responses against each vaccine serogroup were similar between groups. Between-group ratios of hSBA GMTs for MenA were 1.21 (part 1) and 1.11 (part 2), with two-sided 95% confidence interval lower limits (0.94 and 0.87, respectively) greater than the prespecified non-inferiority margin (0.5), thus meeting the primary study objective. No safety concerns were identified. Despite reduced O-acetylation of MenA and increased FS content, serogroup-specific immune responses induced by the fully liquid presentation were similar to those induced by the licensed MenACWY-CRM vaccine, with non-inferior anti-MenA responses. The safety profiles of the vaccine presentations were similar.

Meningococcal disease and vaccination in college students

Neisseria meningitidis is a bacterial pathogen capable of causing rapidly progressing illness from nonspecific symptoms to end-organ failure or death in a matter of hours to days. Despite the availability of meningococcal vaccines, there remains a notable disease incidence peak among individuals aged 18-19 years, with college students at increased risk for disease relative to non-college students. Between 2007 and 2017, as many as one in five colleges in the United States experienced an outbreak of meningococcal disease at their own or a nearby institution. Evidence-based strategies to promote meningococcal vaccination among students can be adapted for the college setting, but barriers exist that limit widespread implementation of these strategies by colleges. In this article, we review meningococcal disease characteristics and epidemiology among US college students, vaccination indications and coverage levels among US college students, as well as college vaccination policies and practices that can impact students' vaccine uptake.