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

Public health impact and cost-effectiveness of introducing MenACWY vaccination strategies in Germany

BACKGROUND

The invasive meningococcal disease (IMD) routine immunization recommendation in Germany is a meningococcal serogroup C (MenC) conjugate vaccine for toddlers aged 12 months with a catch-up for unimmunized up to 17 years. However, there are no recommendations for routine meningococcal serogroups A, C, W, Y (MenACWY) vaccination or for adolescent vaccinations; this differs from other European countries. This analysis aimed to understand the benefits of implementing adolescent MenACWY vaccination in Germany.

METHODS

A static population-cohort model evaluating IMD burden and related health outcomes (e.g., cases, cases with long-term sequelae, deaths) was developed to compare any two meningococcal vaccination strategies. We compared hypothetical vaccination strategies that included different approaches to adolescent vaccination in Germany, such as vaccinating at 13-year olds versus 16-year olds and vaccinating with MenC versus MenACWY. Additional strategies considered the benefit that could be provided by switching the current MenC vaccine recommendation in toddlers to MenACWY.

RESULTS

All strategies that included MenACWY vaccine were effective in decreasing the number of cases, preventing mortality and offered good value for money. The greatest benefit was observed in individuals vaccinated with MenACWY at 12 months and 16 years of age (2,978 IMD cases averted; 563 IMD deaths prevented). Compared with the current strategy of MenC vaccination at 12 months of age, two-dose strategies that included MenACWY reported incremental cost-effectiveness ratios <€13,205 per quality-adjusted life year. Adolescent strategies of MenC or MenACWY vaccine at 16 years old (with no vaccination at 12 months) dominated current vaccination strategies. Adolescent vaccination at 16 years old versus 13 years old offered slightly better value for money.

CONCLUSIONS

With recent increases in IMD cases and outbreaks occurring globally following the COVID-19 pandemic, there is a greater urgency to proactively implement a MenACWY vaccine recommendation to protect adolescents in Germany. This recommendation would provide direct protection to a group at increased risk and offer indirect protection to other population groups. Implementation of a school-based immunization program could increase vaccine uptake and overcome hurdles in adolescent vaccination.

Economic Evaluation of Adolescent Vaccination with Serogroup ACWY and C Meningococcal Vaccines in Germany

INTRODUCTION

Invasive meningococcal disease (IMD) is a rare but serious condition caused by Neisseria meningitidis, with rising cases of serogroups W and Y in Germany. Currently, routine vaccination in Germany includes MenC vaccination in toddlers, and as of early 2024, MenB vaccination has been recommended in infancy. MenACWY vaccination, however, is currently only recommended for high-risk individuals. This study evaluates the potential public health impact and cost-effectiveness of introducing routine adolescent MenACWY or MenC vaccination in Germany.

METHODS

This study presents a health economic evaluation based on a previously published dynamic transmission model, which simulates the introduction of MenACWY vaccination in adolescents in Germany. The evaluation incorporates costs and quality-adjusted life years (QALYs), and is conducted from a societal perspective. Deterministic and probabilistic sensitivity analyses were performed to assess the robustness of the findings and to account for parameter uncertainty.

RESULTS

The introduction of adolescent MenACWY vaccination was estimated to prevent 1467 IMD cases and 156 deaths by 2060, leading to a total gain of 2333 QALYs. The MenACWY vaccination strategy was associated with incremental costs of approximately €306 million, resulting in an incremental cost-effectiveness ratio (ICER) of €131,150 per QALY gained. Scenarios assuming higher levels of carriage protection reduced the ICER to as low as €76,000 per QALY. In contrast, adolescent MenC vaccination had a comparatively minor impact on IMD incidence and mortality, with ICERs exceeding €1 million per QALY. Sensitivity analyses highlighted the significant influence of assumed vaccine carriage protection and duration of protection on the ICER.

CONCLUSIONS

Adolescent MenACWY vaccination in Germany has the potential to reduce the incidence and mortality of IMD, particularly from serogroups W and Y. Although the cost-effectiveness of the strategy depends on several assumptions, particularly the extent of carriage protection, the ICER for MenACWY introduction appears favorable.

Invasive meningococcal disease in South-Eastern European countries: Do we need to revise vaccination strategies?

Invasive meningococcal disease (IMD) is an acute life-threatening infection caused by the gram-negative bacterium, Neisseria meningitidis. Globally, there are approximately half a million cases of IMD each year, with incidence varying across geographical regions. Vaccination has proven to be successful against IMD, as part of controlling outbreaks, and when incorporated into national immunization programs. The South-Eastern Europe Meningococcal Advocacy Group (including representatives from Croatia, the Czech Republic, Greece, Hungary, Poland, Romania, Serbia, Slovenia and Ukraine) was formed in order to discuss the potential challenges of IMD faced in the region. The incidence of IMD across Europe has been relatively low over the past decade; of the countries that came together for the South-Eastern Meningococcal Advocacy Group, the notification rates were lower than the European average for some country. The age distribution of IMD cases was highest in infants and children, and most countries also had a further peak in adolescents and young adults. Across the nine included countries between 2010 and 2020, the largest contributors to IMD were serogroups B and C; however, each individual country had distinct patterns for serogroup distribution. Along with the variations in epidemiology of IMD between the included countries, vaccination policies also differ.

4CMenB journey to the 10-year anniversary and beyond

The 4-component meningococcal serogroup B (MenB) vaccine, 4CMenB, the first broadly protective, protein-based MenB vaccine to be licensed, is now registered in more than 50 countries worldwide. Real-world evidence (RWE) from the last decade confirms its effectiveness and impact, with infant immunization programs showing vaccine effectiveness of 71-95% against invasive MenB disease and cross-protection against non-B serogroups, including a 69% decrease in serogroup W cases in 4CMenB-eligible cohorts in England. RWE from different countries also demonstrates the potential for additional moderate protection against gonorrhea in adolescents. The real-world safety profile of 4CMenB is consistent with prelicensure reports. Use of the endogenous complement human serum bactericidal antibody (enc-hSBA) assay against 110 MenB strains may enable assessment of the immunological effectiveness of multicomponent MenB vaccines in clinical trial settings. Equitable access to 4CMenB vaccination is required to better protect all age groups, including older adults, and vulnerable groups through comprehensive immunization policies.

Immune persistence and booster response of a quadrivalent meningococcal conjugate vaccine (MenACYW-TT) 5 years after primary vaccination of adults at ≥56 years of age

Stage I of this study (NCT04142242) demonstrated the safety and immunogenicity of a booster dose of a licensed quadrivalent meningococcal tetanus toxoid-conjugate vaccine (MenACYW-TT) and immune persistence 3 and 6-7 years after priming in older adults who received either quadrivalent meningococcal polysaccharide vaccine (MPSV4) or MenACYW-TT at ≥56 years of age. Stage II, reported here, assessed the antibody persistence after MenACYW-TT versus MPSV4 priming and the safety and immunogenicity of a booster dose of MenACYW-TT in older adults 5 years after primary vaccination with either MPSV4 or MenACYW-TT. A serum bactericidal assay (hSBA) was used to measure functional antibodies against each serogroup immediately before MenACYW-TT booster vaccination and on day (D) 30 post-booster. Safety was also assessed. Antibody persistence declined 5 years post-primary vaccination, with seroprotection (hSBA titer ≥1:8) rates trending higher in MenACYW-TT- versus MPSV4-primed participants. A robust immune response for all four serogroups was observed on D30 after the MenACYW-TT booster, with higher geometric mean titers and seroprotection rates in MenACYW-TT- versus MPSV4-primed participants. Safety outcomes were similar between the two groups. A single booster dose of MenACYW-TT was well tolerated and immunogenic in older adults, with a higher immune response observed in those primed with MenACYW-TT.

Global Meningococcal Initiative: Insights on antibiotic resistance, control strategies and advocacy efforts in Western Europe

In Western Europe, many countries have robust and well-established surveillance systems and case reporting mechanisms. IMD incidence across Western Europe is low with a predominance of meningococcal serogroup B (MenB). Case confirmation and antimicrobial susceptibility testing is often standardised in this region, with many countries also having robust vaccination programmes in place. Both MenB and MenACWY vaccines form part of National Immunisation Programmes (NIPs) in most European countries, with Sweden only offering vaccination in special circumstances. Despite these established programmes, there remains a critical need for advocacy efforts in affecting change in diagnosis, testing, and treatment. Recent campaigns, such as the World Meningitis Day digital toolkit, have helped raise awareness and draw attention to meningococcal disease. Awareness around antibiotic resistance has also led to the identification of antibiotic-resistant meningococcal strains, with an increase, albeit small, in these strains noted across the region. Countries such as Spain, Portugal, Germany, Switzerland, and France have either reported strains resistant to penicillin, ciprofloxacin and/or isolates with a reduced susceptibility to third-generation cephalosporins.

Recommended Vaccinations During Adolescence: Parents' Knowledge and Behaviors

BACKGROUND

This study aims to evaluate parents' knowledge about vaccination targeted for adolescents.

METHODS

The cross-sectional survey was conducted between February and April 2024 in a sample of parents of adolescents attending middle and high schools in Southern Italy.

RESULTS

Only 10.9% of parents correctly answered all the questions related to the knowledge of vaccinations during adolescence. The results of the multivariate logistic regression model showed that male parents, those who were married/cohabitants, those who had a university degree/masters/PhD, those who were unemployed, those who had a higher number of cohabitants, those who had more than one son/daughter, and parents of older adolescents were significantly more likely to have correct knowledge regarding the vaccinations during adolescence. Overall, more than half of the parents reported that their sons/daughters received the vaccinations indicated during adolescence. Moreover, regarding the vaccinations recommended during adolescence, only 37.2% of parents reported having vaccinated their sons/daughtesr with HPV and tetravalent meningococcal vaccinations. The results of the multivariate logistic regression model showed that those who had correct knowledge regarding vaccination during adolescence, those who had only one son/daughter, parents of older adolescents, those who had a daughter, those who had at least one chronic disease, and those who had a higher number of cohabitants were significantly more likely to have vaccinated their sosn/daughters with HPV and tetravalent meningococcal vaccinations.

CONCLUSIONS

These findings underlined the need to plan immunization campaigns for adolescents and their parents, with the implementation of educational programs specifically targeted to these groups.

Effectiveness and duration of protection of primary and booster immunisation against meningococcal serogroup C disease with meningococcal conjugate C and ACWY vaccines: Systematic review

OBJECTIVES

To estimate vaccine effectiveness (VE) and duration of protection of single primary and booster immunisation with meningococcal C (MenC) and ACWY (MenACWY) conjugate vaccines in preventing MenC invasive meningococcal disease (IMD).

METHODS

We performed a systematic review on studies of VE and immunogenicity (rSBA/hSBA titers) of participants aged 12-23 months for primary and 6-18 years for booster immunisation (last search: 18 August 2023). Risk of bias and certainty of evidence were evaluated (PROSPERO: CRD42020178773).

RESULTS

We identified 10 studies. Two studies reported VE of primary immunisation with MenC vaccines ranging between 90% (74.9 - 96.1) and 84.1% (41.5 - 95.7) for periods of 2 and 7 years, respectively. Eight studies reported immunogenicity of primary immunisation with MenC and/or MenACWY vaccines, of which two reported -in addition- on booster immunisation. The percentage of participants with protective rSBA titers was high after primary immunisation but waned over the following 6 years. A single booster at the age of 7 years or older seems to prolong protection for several years.

CONCLUSIONS

A single dose of MenC or MenACWY vaccine at 12-23 months of age provides robust protection against MenC IMD. Data on booster immunisation are sparse, but indicate prolonged protection for three years at least.

Modelling the Public Health Impact of MenACWY and MenC Adolescent Vaccination Strategies in Germany

INTRODUCTION

Invasive meningococcal disease (IMD) causes significant mortality and long-term sequelae. This study assesses the potential public health impact of adolescent vaccination strategies employing MenACWY and MenC vaccines in Germany, where the existing meningococcal immunisation programme predominantly involves MenC administration in toddlers.

METHODS

A dynamic transmission model was developed to simulate the carriage of five meningococcal serogroup compartments (AY/B/C/W/Other) from 2019 until 2060 within 1-year age groups from 0 to 99 years of age. IMD cases were estimated based on case-carrier ratios. The model considered vaccine effectiveness against carriage acquisition and IMD.

RESULTS

The model predicts that introducing MenACWY adolescent vaccination could lead to a considerable reduction in IMD incidence, with the potential to prevent up to 65 cases per year and a cumulative total of 1467 cases by 2060. This decrease, mainly driven by herd effects, would result in a reduction of IMD incidence across all age groups, regardless of vaccination age. Furthermore, implementing MenACWY vaccination in adolescents is projected to decrease annual MenACWY-related IMD mortality by up to 64%, equating to an overall prevention of 156 IMD deaths by 2060. These protective outcomes are expected to culminate in approximately 2250 life years gained (LYG) throughout the model's projected time horizon. In contrast, the adoption of MenC vaccination in adolescents is predicted to have minimal influence on both IMD incidence and mortality, as well as on LYG.

CONCLUSION

The results of this study demonstrate that implementing MenACWY vaccination for adolescents in Germany is likely to notably reduce IMD incidence and mortality across age groups. However, the introduction of MenC adolescent vaccination shows only limited impact. Considering the extensive healthcare resources typically required for IMD management, these findings suggest the potential for economic benefits associated with the adoption of MenACWY adolescent vaccination, warranting further cost-effectiveness analysis.

Monophosphoryl Lipid A-based Adjuvant to Promote the Immunogenicity of Multivalent Meningococcal Polysaccharide Conjugate Vaccines

Activation of the adaptive immune system requires the engagement of costimulatory pathways in addition to B and T cell Ag receptor signaling, and adjuvants play a central role in this process. Many Gram-negative bacterial polysaccharide vaccines, including the tetravalent meningococcal conjugate vaccines (MCV4) and typhoid Vi polysaccharide vaccines, do not incorporate adjuvants. The immunogenicity of typhoid vaccines is due to the presence of associated TLR4 ligands in these vaccines. Because the immunogenicity of MCV4 is poor and requires boosters, I hypothesized that TLR4 ligands are absent in MCV4 and that incorporation of a TLR4 ligand-based adjuvant would improve their immunogenicity. Consistent with this hypothesis, two Food and Drug Administration-approved MCV4 vaccines, MENVEO and MenQuadfi, lack TLR4 ligands. Admixing monophosphoryl lipid A, a TLR4 ligand-based adjuvant formulation named "Turbo" with MCV4 induced significantly improved IgM and IgG responses to all four meningococcal serogroup polysaccharides in adult and aged mice after a single immunization. Furthermore, in infant mice, a single booster was sufficient to promote a robust IgG response and 100% seroconversion when MCV4 was adjuvanted with Turbo. Turbo upregulated the expression of the costimulatory molecules CD40 and CD86 on B cells, and Turbo-driven adjuvanticity is lost in mice deficient in CD40 and CD86. These data suggest that Turbo induces the required costimulatory molecules for its adjuvant activity and that incorporation of Turbo could make bacterial polysaccharide vaccines more immunogenic, minimize booster requirements, and be cost-effective, particularly for those individuals in low- and middle-income and disease-endemic countries.

Past, present, and future policy considerations regarding meningococcal vaccination in the United States

INTRODUCTION

In 2005, the United States Advisory Committee on Immunization Practices (ACIP) recommended routine vaccination against invasive meningococcal disease (IMD) caused by serogroups A, C, W, and Y (MenACWY) for all 11-12-year-olds, as well as 2-10-year-olds at high risk. In 2010, a booster dose was recommended for all 16-year-olds, as well as for high-risk patients every 3-5 years. In 2015, optional (as opposed to routine) vaccination against meningococcal serogroup B (MenB) at the preferred age of 16-18 years was recommended (Category B, later changed to shared clinical decision-making). In 2023, a vaccine (MenABCWY) against the five serogroups primarily responsible for IMD in the U.S. became available.

AREAS COVERED

This review summarizes the evolution of public policy that led to each milestone vaccine recommendation, reviews epidemiologic data published following the recommendations, and discusses the current state of meningococcal immunization policy.

EXPERT OPINION

The use of MenABCWY has the potential to consolidate policy, improve coverage rates for the five serogroups, address disparities in vaccination coverage, and simplify vaccine delivery.

Distributed genotyping and clustering of Neisseria strains reveal continual emergence of epidemic meningococcus over a century

Core genome multilocus sequence typing (cgMLST) is commonly used to classify bacterial strains into different types, for taxonomical and epidemiological applications. However, cgMLST schemes require central databases for the nomenclature of new alleles and sequence types, which must be synchronized worldwide and involve increasingly intensive calculation and storage demands. Here, we describe a distributed cgMLST (dcgMLST) scheme that does not require a central database of allelic sequences and apply it to study evolutionary patterns of epidemic and endemic strains of the genus Neisseria. We classify 69,994 worldwide Neisseria strains into multi-level clusters that assign species, lineages, and local disease outbreaks. We divide Neisseria meningitidis into 168 endemic lineages and three epidemic lineages responsible for at least 9 epidemics in the past century. According to our analyses, the epidemic and endemic lineages experienced very different population dynamics in the past 100 years. Epidemic lineages repetitively emerged from endemic lineages, disseminated worldwide, and apparently disappeared rapidly afterward. We propose a stepwise model for the evolutionary trajectory of epidemic lineages in Neisseria, and expect that the development of similar dcgMLST schemes will facilitate epidemiological studies of other bacterial pathogens.