Meningococcal ACWYX Conjugate Vaccine in 2-to-29-Year-Olds in Mali and Gambia

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.

Safety and immunogenicity of a pentavalent meningococcal conjugate vaccine versus a quadrivalent meningococcal conjugate vaccine in adults in India: an observer-blind, randomised, active-controlled, phase 2/3 study

BACKGROUND

Meningococcal disease remains an important public health problem globally. We assessed the non-inferiority and the lot-to-lot consistency of a pentavalent meningococcal ACYWX conjugate vaccine (NmCV-5; Serum Institute of India, Pune, India) versus a quadrivalent meningococcal ACWY conjugate vaccine (MenACWY-D) in healthy adults.

METHODS

In this observer-blind, randomised, active-controlled, phase 2/3 study, healthy adults aged 18-85 years were recruited from nine hospitals across seven cities in India. Participants were grouped by age (age 18-29, 30-60, and 61-85 years), and within each age group they were randomly assigned (3:1) to receive either NmCV-5 or MenACWY-D (Sanofi Pasteur). In the age 18-29 years group, participants were additionally randomly assigned (1:1:1:1) to either lot A, lot B, or lot C of NmCV-5 or MenACWY-D. Block randomisation was used (block sizes of 4, 8, and 12). Study participants and study personnel were masked to treatment assignment. Participants received either a 0·5 mL dose of NmCV-5, containing 5 μg each of conjugated A, C, W, Y, and X polysaccharides, or 0·5 mL MenACWY-D, containing 4 μg of each of conjugated A, C, W, and Y polysaccharides. Vaccinations were administered intramuscularly in the deltoid muscle. The primary outcomes were seroresponse (non-inferiority margin of -10%) and geometric mean titres (GMTs; non-inferiority margin of 0·5) in all participants, and lot-to-lot consistency of NmCV-5 (in participants aged 18-29 years; consistency was shown if the geometric mean ratio [GMR] 95% CIs were within the limit interval of 0·5 to 2). For non-inferiority, serogroup X immune response in the NmCV-5 group was compared with the lowest immune response among serogroups A, C, W, and Y in the MenACWY-D group. Immunogenicity was assessed with a serum bactericidal activity assay that used baby rabbit serum as the complement (rSBA) on days 1 and 29 in the modified per-protocol population (including all participants who were randomly assigned, received vaccine, had a post-vaccination rSBA measurement up to 121 days after vaccination, and no major protocol violations). Solicited events were collected for 7 days and serious adverse events were collected for 180 days, and assessed in the safety population (all participants who received vaccination). This study is registered with ClinicalTrials.gov, NCT04358731, and CTRI, CTRI/2019/12/022436, and is now complete.

FINDINGS

Between Dec 27, 2019, and Sept 19, 2020, 1712 individuals were screened, of whom 1640 were randomly assigned and received NmCV-5 (n=1233) or MenACWY-D (n=407; mean age 26·4 years [SD 12·2], 551 [33·6%] of 1640 were female, and 1089 [66·4%] were male). 1441 participants were aged 18-29 years (362 received lot A, 360 received lot B, and 361 received lot C of NmCV-5 and 357 received MenACWY-D, with one participant mis-randomised by age group and excluded from lot-to-lot consistency analysis). Non-inferiority of NmCV-5 against MenACWY-D was met in terms of seroresponse rates and GMT ratios for all five serogroups. The seroresponse rates were 84·3% (97·5% CI 81·7 to 86·7; serogroup A) or higher in the NmCV-5 group and 54·5% (48·5 to 60·3; serogroup A) or higher in the MenACWY-D group, with the difference in the seroresponse rate between vaccine groups ranging from 0·2 (97·5% CI -2·2 to 2·6) for serogroup W to 29·8 (24·4 to 35·2) for serogroup A. GMTs on day 29 were 7016·9 (97·5% CI 6475·7 to 7603·4; serogroup Y) or higher in the NmCV-5 group and 3646·8 (3188·2 to 4171·5; serogroup Y) or higher in the MenACWY-D group, with GMT ratios between vaccine groups for serogroups A, C, Y, and W ranging from 1·9 (97·5% CI 1·5-2·3) for serogroup W to 2·5 (2·2-2·8) for serogroup A. NmCV-5 induced robust immune responses against serogroup X. Lot-to-lot consistency of NmCV-5 was found for all five serogroups, with 95% CIs for the GMT ratio for each pair of lots being between 0·5 and 2: the lowest lower bound and the highest upper bound of the 95% CI for the GMR between NmCV-5 lot A and lot B were 0·6 and 1·4, between lot A and lot C were 0·7 and 1·6, and between lot B and lot C were 0·8 and 1·6, respectively, for any of the five serogroups. At least one solicited adverse event was reported by 527 (42·7%) of 1233 participants in the NmCV-5 group and 142 (34·9%) of 407 in the MenACWY-D group. No serious adverse events occurred that were determined to be causally related to vaccination.

INTERPRETATION

NmCV-5 was non-inferior to MenACWY-D in terms of seroresponse and GMTs, was safe, and demonstrated lot-to-lot consistency. NmCV-5 is prequalified by WHO and was rolled out in the African meningitis belt in April, 2024.

FUNDING

Serum Institute of India.

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.

Refinement and optimisation of Neisseria gonorrhoeae NHBA and MetQ vaccine candidates

Neisseria gonorrhoeae has a significant impact on reproductive health with an estimated 82 million new cases of infection per year worldwide. Due to the ongoing emergence of multidrug-resistant N. gonorrhoeae strains, the high number of asymptomatic cases, and the risk of disease sequelae, the development of a gonococcal vaccine is urgently needed. We have previously described two potential gonococcal vaccine antigens, cNHBA (C-terminal fragment of the Neisseria Heparin Binding Antigen) and MetQ (methionine-binding protein). This study aimed to optimise these antigens for improved immune responses and to facilitate vaccine production, by investigating cNHBA fusions with the full-length MetQ protein or N-terminal and C-terminal MetQ fragments (Met1 and Met2, respectively) adjuvanted with aluminium hydroxide. The cNHBA and MetQ fragments and fusion antigens were all immunogenic in mice, generating a predominantly IgG1 response. Antibodies mediated bacterial killing via both serum bactericidal activity (SBA) and opsonophagocytic activity (OPA), and reduced adherence to cervical and urethral epithelial cells. Among the antigen fusions tested, MetQ-cNHBA and cNHBA-Met2 generated the highest SBA, OPA and adherence blocking titres and are proposed as promising optimised antigens for N. gonorrhoeae vaccine development.

Collecting and reporting adverse events in low-income settings-perspectives from vaccine trials in the Gambia

BACKGROUND

Despite Africa's significant infectious disease burden, it is underrepresented in global vaccine clinical trials. While this trend is slowly reversing, it is important to recognize and mitigate the challenges that arise when conducting vaccine clinical trials in this environment. These challenges stem from a variety of factors peculiar to the population and may negatively impact adverse event collection and reporting if not properly addressed.

METHODS

As a team of clinical researchers working within the MRCG (Medical Research Council Unit The Gambia), we have conducted 12 phase 1 to 3 vaccine trials over the past 10 years. In this article, we discuss the challenges we face and the strategies we have developed to improve the collection and reporting of adverse events in low-income settings.

OUTCOME

Healthcare-seeking behaviors in the Gambia are influenced by spiritual and cultural beliefs as well as barriers to accessing orthodox healthcare; participants in trials may resort to non-orthodox care, reducing the accuracy of reported adverse events. To address this, trial eligibility criteria prohibit self-treatment and herbal product use during trials. Instead, round-the-clock care is provided to trial participants, facilitating safety follow-up. Constraints in the healthcare system in the Gambia such as limitations in diagnostic tools limit the specificity of diagnosis when reporting adverse events. To overcome these challenges, the Medical Research Council Unit maintains a Clinical Services Department, offering medical care and diagnostic services to study participants. Sociocultural factors, including low literacy rates and social influences, impact adverse event collection. Solicited adverse events are collected during home visits on paper-based or electronic report forms. Community engagement meetings are held before each study starts to inform community stakeholders about the study and answer any questions they may have. These meetings ensure that influential members of the community understand the purpose of the study and the risks and benefits of participating in the trial. This understanding makes them more likely to support participation within their communities.

CONCLUSION

Conducting ethical vaccine clinical trials in resource-limited settings requires strategies to accurately collect and report adverse events. Our experiences from the Gambia offer insights into adverse event collection in these settings.

A perspective on the novel pentavalent Men5CV (NmCV-5) meningitis vaccine and Nigeria's pioneering rollout campaign

The burden of meningitis poses great challenges for neurology and global health, manifesting with a range of symptoms from mild fever and headaches, to severe long term complications such as paralysis and cognitive impairment.. Unfortunately, those living in endemic regions, especially survivors, are often confronted with the harsh reality of reduced quality of life as measured by disability-adjusted life years. Meningitis is one of the leading causes of mortality and morbidity, especially in the meningitis belt of sub-Saharan Africa, with a recorded disease burden of over 2.5 million cases globally and children under five disproportionately impacted. This paper examines the global burden of meningitis, exploring its prevalence and impact across different regions. It further analyzes the evolution of vaccination strategies for meningitis prevention, emphasizing the recent development and introduction of the novel Men5CV meningococcal conjugate vaccine. Recurrent meningitis outbreaks across the meningitis belt have resulted in significant mortality over decades. A major turning point in the fight against the serogroup A epidemic was the development of the MenAfriVac vaccine, which resulted in declining cases. However, serogroups C, W, and X continue to pose problems. The novel pentavalent (Men5CV) vaccine has emerged as a remarkable advancement in the fight against meningitis, with its safety and effectiveness against a variety of serogroups, including the elusive serogroup X, demonstrated in clinical trials. Its pre-qualification by the World Health Organization (WHO), and subsequent recommendation for incorporation into routine immunization programs issued a new era with the potential for meningitis eradication. Nigeria now sets a benchmark for other nations in the meningitis zone, becoming the first country in the world to roll out the new Men5CV vaccines. Funding from organizations like Gavi, the Vaccine Alliance, highlights the importance of coordinated international efforts aligned with the WHO's roadmap for meningitis elimination by 2030. Stakeholder involvement, extensive immunization campaigns, and a strong healthcare infrastructure are all practical recommendations for public health integration.

A randomized study to evaluate the safety and immunogenicity of a pentavalent meningococcal vaccine

A randomized, active-controlled, double-blind, first-in-human, phase 1 study was conducted in healthy Korean adults to evaluate the safety, tolerability, and immunogenicity of EuNmCV-5, a new pentavalent meningococcal vaccine targeting serogroups A, C, W, X, and Y. Sixty participants randomly received a single dose of either EuNmCV-5 or MenACWY-CRM, a quadrivalent vaccine containing serogroups A, C, W, and Y. Safety was assessed through monitoring anaphylactic reactions, adverse events for 28 days, and serious adverse events over 180 days. Immunogenicity was assessed via rabbit complement-dependent serum bactericidal antibody (rSBA) assay. EuNmCV-5 was safe, well-tolerated, and elicited a substantial antibody titer increase. The seroprotection rates exceeded 96.7%, and the seroconversion rates were over 85% for all the targeted serogroups. It showed higher seroconversion rates against serogroups A and C (p = 0.0016 and 0.0237, respectively) and elicited a substantial increase in GMT for all targeted serogroups compared to the MenACWY-CRM.ClinicalTrials.gov identifier: NCT05739292.

Facilitating the development of urgently required combination vaccines

The essence of a vaccine lies in its ability to elicit a set of immune responses specifically directed at a particular pathogen. Accordingly, vaccines were historically designed, developed, registered, recommended, procured, and administered as monopathogen formulations. Nonetheless, the control and elimination of an astonishing number of diseases was realised only after several once-separate vaccines were provided as combinations. Unfortunately, the current superabundance of recommended and pipeline vaccines is now at odds with the number of acceptable vaccine administrations and feasible health-care visits for vaccine recipients and health-care providers. Yet, few new combinations are in development because, in addition to the scientific and manufacturing hurdles intrinsic to coformulation, developers face a gauntlet of regulatory, policy, and commercialisation obstacles in a milieu still largely designed for monopathogen vaccines. We argue here that national policy makers and public health agencies should prospectively identify and advocate for the development of new multipathogen combination vaccines, and suggest ways to accelerate the regulatory pathways to licensure of combinations and other concrete, innovative steps to mitigate current obstacles.

WHO Strategic Advisory Group of Experts on Immunization recommendations for use of a novel pentavalent meningococcal ACWXY vaccine: a critical step towards ending meningococcal epidemics in Africa

A new pentavalent meningococcal ACWXY vaccine is poised to have a dramatic impact on the burden of meningococcal disease in the meningitis belt of Africa. Implementation of this vaccine is a critical step towards the first visionary goal of WHO's roadmap to defeat meningitis by 2030: eliminating bacterial meningitis epidemics.

Three novel pentavalent meningococcal vaccines

Invasive meningococcal disease (IMD) is rare in travellers but associated with high mortality and long-term sequelae. Six serogroups (MenABCWXY) account for more than 90% of IMD. Three pentavalent vaccines are on the horizon: two MenABCWY, both with a 0–6 month schedule, highly immunogenic and well tolerated, and one single-dose MenACWXY.

Public health trends in neurologically relevant infections: a global perspective

Neuroinfectious diseases represent a growing threat to public health globally. Infections of the central nervous system remain challenging to diagnose and treat, partially driven by the fact that a high proportion of emerging pathogens are capable of causing neurological disease. Many of the trends driving the emergence of novel pathogens, including climate change, ecological degradation, urbanization, and global travel, have accelerated in recent years. These circumstances raise concern for the potential emergence of additional pathogens of pandemic potential in the coming years, necessitating a stronger understanding of the forces that give rise to the emergence and spread of neuroinvasive pathogens and a commitment to public health infrastructure to identify and treat these diseases. In this review, we discuss the clinical and epidemiological features of three types of emerging neuroinvasive pathogens of significant public health consequences that are emblematic of key ongoing trends in global health. We first discuss dengue viruses in the context of climate change, considering the environmental factors that allow for the expansion of the geographic range and seasonal population of the viruses' vector. We then review the rising prevalence of fungal meningitis secondary to medical tourism, a trend representative of the highly globalized nature of modern healthcare. Lastly, we discuss the increasing prevalence of antibiotic-resistant neurological infections driven by the intersection of antibiotic overuse in medical and agricultural settings. Taken together, the rising prevalence of these conditions necessitates a recommitment to investment in public health infrastructure focused on local and global infectious disease surveillance coupled with ongoing development of novel therapeutics and vaccines for emerging pathogens. Such emerging threats also obviate the need to address the root causes driving the emergence of novel infectious diseases, including a sustained effort to address anthropogenic climate change and environmental degradation.

Meningitis in Niger Republic amidst COVID-19: current issues and novel recommendations

Amidst coronavirus disease 2019 (COVID-19), there has been a misplaced priority on meningitis in the Niger Republic, thus refocusing resources and attention away from the continuing meningitis campaign in the Niger Republic. The over-strained state of public health resources and staff has also led to decreased surveillance, postponed diagnoses, and constrained immunization efforts in Niger Republic. This review aims to bridge the gaps regarding meningitis amid COVID-19 in Niger Republic and offer recommendations to government to mitigate meningitis in the country, with the hope of finding a permanent solution to this debilitating disease. The authors reviewed 45 past and present pieces of literature on meningitis and COVID-19 from 2013 to 2023 in well-renowned scientific databases such as PubMed, ResearchGate, Google Scholar, African Journals Online, Medline, and Embase. Since 2015, Niger Republic has experienced multiple meningitis epidemics that have resulted in 20, 789 cases and 1, 369 deaths [a case fatality rate (CFR) of 6.6%]. A total of 231 cases of meningitis were reported from 1 November 2021 to 31 January 2022. And recently, 559 cases of meningitis (of which 111 are laboratory confirmed), including 18 deaths (overall CFR 3.2%), occurred in the Zinder region, southeast of Niger Republic, from 1 November 2022 to 27 January 2023. Meningitis remains a public health concern in the world, especially in Niger Republic, which could lead to serious long-term complications. Therefore, adequate and novel measures and therapeutic actions should be implemented by the Niger Government to lessen the burden of the disease in the country.

A Perspective on the Strategy for Advancing ETVAX®, An Anti-ETEC Diarrheal Disease Vaccine, into a Field Efficacy Trial in Gambian Children: Rationale, Challenges, Lessons Learned, and Future Directions

For the first time in over 20 years, an Enterotoxigenic Escherichia coli (ETEC) vaccine candidate, ETVAX®, has advanced into a phase 2b field efficacy trial for children 6-18 months of age in a low-income country. ETVAX® is an inactivated whole cell vaccine that has gone through a series of clinical trials to provide a rationale for the design elements of the Phase 2b trial. This trial is now underway in The Gambia and will be a precursor to an upcoming pivotal phase 3 trial. To reach this point, numerous findings were brought together to define factors such as safe and immunogenic doses for children, and the possible benefit of a mucosal adjuvant, double mutant labile toxin (dmLT). Considering the promising but still underexplored potential of inactivated whole cells in oral vaccination, we present a perspective compiling key observations from past ETVAX® trials that informed The Gambian trial design. This report will update the trial's status and explore future directions for ETEC vaccine trials. Our aim is to provide not only an update on the most advanced ETEC vaccine candidate but also to offer insights beneficial for the development of other much-needed oral whole-cell vaccines against enteric and other pathogens.

Microevolution and Its Impact on Hypervirulence, Antimicrobial Resistance, and Vaccine Escape in Neisseria meningitidis

Neisseria meningitidis is commensal of the human pharynx and occasionally invades the host, causing the life-threatening illness invasive meningococcal disease. The meningococcus is a highly diverse and adaptable organism thanks to natural competence, a propensity for recombination, and a highly repetitive genome. These mechanisms together result in a high level of antigenic variation to invade diverse human hosts and evade their innate and adaptive immune responses. This review explores the ways in which this diversity contributes to the evolutionary history and population structure of the meningococcus, with a particular focus on microevolution. It examines studies on meningococcal microevolution in the context of within-host evolution and persistent carriage; microevolution in the context of meningococcal outbreaks and epidemics; and the potential of microevolution to contribute to antimicrobial resistance and vaccine escape. A persistent theme is the idea that the process of microevolution contributes to the development of new hyperinvasive meningococcal variants. As such, microevolution in this species has significant potential to drive future public health threats in the form of hypervirulent, antibiotic-resistant, vaccine-escape variants. The implications of this on current vaccination strategies are explored.