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

Joint consensus on reducing the burden of invasive meningococcal disease in the Asia-Pacific region

Invasive meningococcal disease (IMD) imposes a heavy burden of mortality and life-long sequelae on infected individuals and has devastating impacts on their family members. International data show that meningococcal vaccination programs have reduced IMD incidence and changed the serogroup distribution of the disease. Furthermore, newer data show that although the public health measures in response to the coronavirus disease 2019 (COVID-19) pandemic temporarily reduced the incidence of IMD, there has been a resurgence in the years since. In the Asia-Pacific (APAC) region, many countries do not include meningococcal vaccines in their routine vaccination programs, and approaches to IMD surveillance are inconsistent. This review summarizes recent data and consensus statements from a group of experts from selected APAC countries on the burden of IMD in the region, evidence for vaccination, and how barriers to IMD vaccination may be addressed.

Genomic characterization of invasive Neisseria meningitidis in Spain (2011/12-2022/23): expansion of clonal complex 213 and the potential threat to 4CMenB vaccine strain coverage

Invasive meningococcal disease (IMD) is associated with significant global morbidity and mortality and is addressed by conjugated polysaccharide and subcapsular vaccines. In Spain, data on 4CMenB vaccine strain coverage and antimicrobial susceptibility are limited. This study aimed to describe the genomic epidemiology, predict 4CMenB vaccine strain coverage, and assess antimicrobial susceptibility of 323 Neisseria meningitidis isolates causing IMD, collected from 57 Clinical Microbiology Laboratories in Spain over 12 years (2011/12-2022/23). Whole genome sequencing was performed to identify serogroup, clonal complex (cc), and antimicrobial resistance determinants. Vaccine strain coverage for serogroup B (MenB) isolates was predicted using the genetic Meningococcal Antigen Typing System approach. The most prevalent serogroups were B (57.9%), W (21.4%), C (10.4%), and Y (8.4%). MenB predominated throughout most seasons, except during the 2019/20 season when serogroup W peaked. Post-COVID-19 pandemic, MenB remained the most frequent (70.2%). Thirteen cc were identified among MenB isolates, with cc213 being the most prevalent (40.1%). Only 28.9% of MenB isolates were predicted to be covered by 4CMenB, with cc213 showing an exceptionally low coverage rate (5.3%) due to antigenic variants poorly targeted by the vaccine. Notably, cc213 was responsible for twice the proportion of MenB cases in 4CMenB-vaccinated versus unvaccinated. All isolates were susceptible to third generation cephalosporins, and 13.5% showed penicillin resistance. This study highlights the alarming prevalence of cc213 among MenB IMD cases in Spain and the limited 4CMenB coverage against this cc. The disproportionate representation of cc213 in vaccinated individuals underscores its potential to compromise vaccine effectiveness.

Sex differences in bacterial meningitis and associations with socioeconomic indicators: a systematic review and meta-analysis with metaregression

INTRODUCTION

We aimed to describe global sex-specific proportions and case fatality ratios of bacterial meningitis and to explore their associations with the Human Development Index (HDI) and Gender Inequality Index (GII).

METHODS

Google Scholar and MEDLINE (via PubMed.gov) were searched in January 2022 using the terms "bacterial meningitis" and "mortality". Studies with a mean observation period after the year 1940 and reporting ≥10 patients with community-acquired bacterial meningitis and their survival status were included, irrespective of the participants' age. Studies that selected participants by specific risk factors, reported specific pathogens only, or had >10% missing outcomes were disregarded. Data were extracted by one researcher and validated by a second researcher. The main outcomes, sex-specific proportions and case fatality ratios, were analysed using random-effects models. Associations with HDI and GII were explored using metaregression.

RESULTS

In this meta-analysis with metaregression, from 371 studies with 157 656 meningitis episodes, 217 (58%) reported the patients' sex and 41 (11%) reported sex-specific outcomes. Proportion of males was 58% (95% CI 57%-59%, prediction interval (PI) 45%-71%). Case fatality ratios were slightly higher in females (male-to-female fatality ratio, 0.89, 95% CI 0.78 to 1.01, PI 0.53-1.49). The size of the male proportion was strongly associated with HDI (per index point, -0.64, 95% CI -0.88 to -0.40; R2 16%; p<0.001) and GII (per index point, 0.61, 95% CI 0.39 to 0.83; R2 19%; p<0.001). Sex-specific case fatality ratios were weakly associated with HDI (per index point, 0.53, 95% CI -0.19 to 1.25; R2 2%; p=0.15) and GII (per index point, -0.58, 95% CI -1.55 to 0.39; R2 7%; p=0.24).

CONCLUSION

Based on worldwide reporting from the last 80 years, we show that indicators of human development and gender inequality are associated with sex-based disparities and case fatality ratios in bacterial meningitis.

Vaccination Coverage of People Living with HIV: Before and after Interventional Action

This is a quasi-experimental study that assessed PLHIV vaccination coverage before and after health professionals participated in a training course on PLHIV immunization. The vaccination coverage of 645 PLHIV was assessed in the pre-intervention phase. The vaccine with the best coverage was diphtheria and tetanus (82.64%) and the one with the lowest rate of adequately vaccinated was measles, mumps, and rubella (38.27%). Individuals aged between 30 and 39 years had a 74.00% (1-0.26) lower chance of having the full vaccination schedule when compared to those aged between 10 and 19 years, and among those over 40 years, the chance was 87.00% (1-0.13) lower. Those who were vaccinated in Specialized Care Services (SCS) were 5.77 times more likely to be adequately vaccinated when compared to those who were vaccinated in other health services. Regarding the entire vaccination schedule evaluated, the number of adequately vaccinated increased from 47 (7.29%) to 76 (11.78%). Interventions targeting health professionals were effective in increasing vaccination coverage among PLHIV; however, the achieved coverage remained below the desired level. It is necessary to act on health professionals' knowledge and other aspects to effectively increase vaccination coverage.

Invasive meningococcal disease in older adults: current perspectives and call for action

PURPOSE

Invasive meningococcal disease (IMD) is a devastating condition. While most attention is directed towards disease in children and adolescents, IMD poses an important cause of morbidity and mortality in adults ≥60 years. While immunization is a critical component of healthy ageing strategies, meningococcal immunization is not routinely offered to older adults. The aim of this review was to summarize clinical and epidemiological aspects of IMD and available immunization strategies, with a particular focus on disease in older individuals, to emphasize the importance of this rather neglected area.

METHODS

An expert working group was established to evaluate clinical and epidemiological data to raise awareness of IMD in older individuals, and develop suggestions to improve the existing burden.

RESULTS

Routine child and adolescent meningococcal immunization has substantially reduced IMD in these targeted populations. Consequently, prevalence and proportion of IMD among those ≥60 years, mostly unvaccinated, is increasing in developed countries (accounting for up to 25% of cases). IMD-related mortality is highest in this age-group, with substantial sequelae in survivors. IMD due to serogroups W and Y is more prevalent among older adults, often with atypical clinical features (pneumonia, gastrointestinal presentations) which may delay timely treatment.

CONCLUSIONS

IMD in older adults remains overlooked and greater awareness is required at clinical and societal levels. We encourage clinicians and immunization policy makers to reconsider IMD, with a call for action to remedy existing inequity in older adult access to protective meningococcal immunization.

Propositive follow-up: Long-term immune responses to the 4CMenB and MenACWY vaccines in people living with HIV

BACKGROUND

People living with HIV have an increased risk of meningococcal disease. The Propositive trial evaluated co-administration of two doses of a four-component recombinant protein-based MenB vaccine (4CMenB) and a quadrivalent conjugate polysaccharide MenACWY vaccine (MenACWY-CRM197) given 1 month apart in people with HIV. The follow-up trial assessed the immunogenicity of these vaccines at 1.5 and 2.5 years after primary vaccination.

METHODS

Participants who completed the parent Propositive trial were invited to the follow-up study. Immunogenicity analysis was performed at 18 and 30 months after primary vaccination. Primary outcome measures were serum bactericidal antibody (SBA) geometric mean titres (GMTs) against three MenB reference strains and the proportion of participants maintaining a protective SBA titre of ≥4 at 18 and 30 months. Secondary outcome measures were SBA GMTs against MenA, C, W, and Y serogroups and the proportion of participants maintaining a protective SBA titre of ≥8 at 18 and 30 months. The trial is registered with Clinicaltrials.gov (NCT042394300).

RESULTS

A total of 40 participants aged 22-47 years were enrolled. Geometric mean titres waned by 18 and 30 months but remained higher than pre-vaccination for all MenB strains and MenA, C, W, and Y. In total, 75%-85% of participants retained protective SBA titres by 30 months against individual MenB strains, whereas 68.8% of patients retained protective antibody titres against all three MenB strains. Antibodies against MenC waned more rapidly than did those against MenA, W, and Y. The proportion of participants with protective titres against MenC at 30 months was also lower (46.9%) than that with protective titres against MenA (87.5%), W (78.1%), and Y (87.5%).

CONCLUSIONS

Immune responses against MenB in our cohort of people living with HIV at 2.5 years of follow-up were reassuring, with 68.8% of participants retaining protection against all three reference strains. However, responses against MenC were lower than those against MenA, W, and Y serogroups.

Geographical distribution of invasive meningococcal disease and carriage: A spatial analysis

Little information exists concerning the spatial relationship between invasive meningococcal disease (IMD) cases and Neisseria meningitidis (N. meningitidis) carriage. The aim of this study was to examine whether there is a relationship between IMD and asymptomatic oropharyngeal carriage of meningococci by spatial analysis to identify the distribution and patterns of cases and carriage in South Australia (SA). Carriage data geocoded to participants' residential addresses and meningococcal case notifications using Postal Area (POA) centroids were used to analyse spatial distribution by disease- and non-disease-associated genogroups, as well as overall from 2017 to 2020. The majority of IMD cases were genogroup B with the overall highest incidence of cases reported in infants, young children, and adolescents. We found no clear spatial association between N. meningitidis carriage and IMD cases. However, analyses using carriage and case genogroups showed differences in the spatial distribution between metropolitan and regional areas. Regional areas had a higher rate of IMD cases and carriage prevalence. While no clear relationship between cases and carriage was evident in the spatial analysis, the higher rates of both carriage and disease in regional areas highlight the need to maintain high vaccine coverage outside of the well-resourced metropolitan area.

Meningococcal Septic Oligoarthritis: An Unusual Presentation Revealing Concurrent Multiple Myeloma

Meningococcal invasive disease is rare in immunocompetent hosts but may occur in patients with risk factors. Septic arthritis is an uncommon form of presentation and is usually due to surgical colonization or hematogenous dissemination. We present a case of a 73-year-old woman, who recently underwent knee replacement surgery, presenting with right knee and left shoulder pain, swelling, and reduced range of motion. Antibiotic therapy was promptly initiated, and the identification of invasive meningococcal disease with septic arthritis was possible through blood cultures and synovial fluid analysis.

Meningococcal B Immunisation in Adults and Potential Broader Immunisation Strategies: A Narrative Review

Recombinant vaccines against invasive meningococcal disease due to Neisseria meningitidis serogroup B (MenB) have shown substantial impact in reducing MenB disease in targeted populations. 4CMenB targets four key N. meningitidis protein antigens; human factor H binding protein (fHbp), Neisserial heparin binding antigen (NHBA), Neisseria adhesin A (NadA) and the porin A protein (PorA P1.4), with one or more of these expressed by most pathogenic MenB strains, while MenB-FHbp targets two distinct fHbp variants. While many countries recommend MenB immunisation in adults considered at high risk due to underlying medical conditions or immunosuppression, there are no recommendations for routine use in the general adult population. We reviewed the burden of MenB in adults, where, while incidence rates remain low (and far lower than in young children < 5 years of age at greatest risk), a substantial proportion of MenB cases (20% or more) is now observed in the adult population; evident in Europe, Australia, and in the United States. We also reviewed immunogenicity data in adults from clinical studies conducted during MenB vaccine development and subsequent post-licensure studies. A 2-dose schedule of 4CMenB generates hSBA titres ≥ 1:4 towards all four key vaccine target antigens in up to 98-100% of subjects. For MenB-FHbp, a ≥ fourfold rise in hSBA titres against the four primary representative test strains was observed in 70-95% of recipients following a 3-dose schedule. While this suggests potential benefits for MenB immunisation if used in adult populations, data are limited (especially for adults > 50 years) and key aspects relating to duration of protection remain unclear. Although a broader adult MenB immunisation policy could provide greater protection of the adult population, additional data are required to support policy decision-making.