Challenges and opportunities for meningococcal vaccination in the developing world

Prediction by genetic MATS of 4CMenB vaccine strain coverage of invasive meningococcal serogroup B isolates circulating in Taiwan between 2003 and 2020

Neisseria meningitidis serogroup B (NmB) strains have diverse antigens, necessitating methods for predicting meningococcal serogroup B (MenB) vaccine strain coverage. The genetic Meningococcal Antigen Typing System (gMATS), a correlate of MATS estimates, predicts strain coverage by the 4-component MenB (4CMenB) vaccine in cultivable and non-cultivable NmB isolates. In Taiwan, 134 invasive, disease-causing NmB isolates were collected in 2003-2020 (23.1%, 4.5%, 5.2%, 29.8%, and 37.3% from individuals aged ≤11 months, 12-23 months, 2-4 years, 5-29 years, and ≥30 years, respectively). NmB isolates were characterized by whole-genome sequencing and vaccine antigen genotyping, and 4CMenB strain coverage was predicted using gMATS. Analysis of phylogenetic relationships with 502 global NmB genomes showed that most isolates belonged to three global hyperinvasive clonal complexes: ST-4821 (27.6%), ST-32 (23.9%), and ST-41/44 (14.9%). Predicted strain coverage by gMATS was 62.7%, with 27.6% isolates covered, 2.2% not covered, and 66.4% unpredictable by gMATS. Age group coverage point estimates ranged from 42.9% (2-4 years) to 66.1% (≤11 months). Antigen coverage estimates and percentages predicted as covered/not covered were highly variable, with higher estimates for isolates with one or more gMATS-positive antigens than for isolates positive for one 4CMenB antigen. In conclusion, this first study on NmB strain coverage by 4CMenB in Taiwan shows 62.7% coverage by gMATS, with predictable coverage for 29.8% of isolates. These could be underestimated since the gMATS calculation does not consider synergistic mechanisms associated with simultaneous antibody binding to multiple targets elicited by multicomponent vaccines or the contributions of minor outer membrane vesicle vaccine components.IMPORTANCEMeningococcal diseases, caused by the bacterium Neisseria meningitidis (meningococcus), include meningitis and septicemia. Although rare, invasive meningococcal disease is often severe and can be fatal. Nearly all cases are caused by six meningococcal serogroups (types), including meningococcal serogroup B. Vaccines are available against meningococcal serogroup B, but the antigens targeted by these vaccines have highly variable genetic features and expression levels, so the effectiveness of vaccination may vary depending on the strains circulating in particular countries. It is therefore important to test meningococcal serogroup B strains isolated from specific populations to estimate the percentage of bacterial strains that a vaccine can protect against (vaccine strain coverage). Meningococcal isolates were collected in Taiwan between 2003 and 2020, of which 134 were identified as serogroup B. We did further investigations on these isolates, including using a method (called gMATS) to predict vaccine strain coverage by the 4-component meningococcal serogroup B vaccine (4CMenB).

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.

Clinical diagnosis in paediatric patients at urban primary health care facilities in southern Malawi: a longitudinal observational study

Background

Despite health centres being the first point of contact of care, there are challenges faced in providing care to patients at this level. In Malawi, service provision barriers reported at this level included long waiting times, high numbers of patients and erratic consultation systems which lead to mis-diagnosis and delayed referrals. Proper case management at this level of care is critical to prevent severe disease and deaths in children. We aimed to adopt Emergency, Triage, Assessment and Treatment algorithm (ETAT) to improve ability to identify severe illness in children at primary health centre (PHC) through comparison with secondary level diagnoses.

Methods

We implemented ETAT mobile Health (mHealth) at eight urban PHCs in Blantyre, Malawi between April 2017 and September 2018. Health workers and support staff were trained in mHealth ETAT. Stabilisation rooms were established and equipped with emergency equipment. All PHCs used an electronic tracking system to triage and track sick children on referral to secondary care, facilitated by a unique barcode. Support staff at PHC triaged sick children using ETAT Emergency (E), Priority (P) and Queue (Q) symptoms and clinician gave clinical diagnosis. The secondary level diagnosis was considered as a gold standard. We used statistical computing software R (v3.5.1) and used exact 95% binomial confidence intervals when estimating diagnosis agreement proportions.

Results

Eight-five percentage of all cases where assigned to E (9.0%) and P (75.5%) groups. Pneumonia was the most common PHC level diagnosis across all three triage groups (E, P, Q). The PHC level diagnosis of trauma was the most commonly confirmed diagnosis at secondary level facility (85.0%), while a PHC diagnosis of pneumonia was least likely to be confirmed at secondary level (39.6%). The secondary level diagnosis least likely to have been identified at PHC level was bronchiolitis 3 (5.2%). The majority of bronchiolitis cases (n = 50; (86.2%) were classified as pneumonia at the PHC level facility.

Conclusions

Implementing a sustainable and consistent ETAT approach with stabilisation and treatment capacity at PHC level reinforce staff capacity to diagnose and has the potential to reduce other health system costs through fewer, timely and appropriate referrals.

Immunogenicity and safety of a quadrivalent meningococcal tetanus toxoid-conjugate vaccine (MenACYW-TT) vs. a licensed quadrivalent meningococcal tetanus toxoid-conjugate vaccine in meningococcal vaccine-naïve and meningococcal C conjugate vaccine-primed toddlers: a phase III randomised study

Vaccination remains the best strategy to reduce invasive meningococcal disease. This study evaluated an investigational tetanus toxoid-conjugate quadrivalent meningococcal vaccine (MenACYW-TT) vs. a licensed tetanus toxoid-conjugate quadrivalent meningococcal vaccine (MCV4-TT) (NCT02955797). Healthy toddlers aged 12–23 months were included if they were either meningococcal vaccine-naïve or MenC conjugate (MCC) vaccine-primed (≥1 dose of MCC prior to 12 months of age). Vaccine-naïve participants were randomised 1:1 to either MenACYW-TT (n = 306) or MCV4-TT (n = 306). MCC-primed participants were randomised 2:1 to MenACYW-TT (n = 203) or MCV4-TT (n = 103). Antibody titres against each of the four meningococcal serogroups were measured by serum bactericidal antibody assay using the human complement. The co-primary objectives of this study were to demonstrate the non-inferiority of MenACYW-TT to MCV4-TT in terms of seroprotection (titres ≥1:8) at Day 30 in both vaccine-naïve and all participants (vaccine-naïve and MCC-primed groups pooled). The immune response for all four serogroups to MenACYW-TT was non-inferior to MCV4-TT in vaccine-naïve participants (seroprotection: range 83.6–99.3% and 81.4–91.6%, respectively) and all participants (seroprotection: range 83.6–99.3% and 81.4–98.0%, respectively). The safety profiles of both vaccines were comparable. MenACYW-TT was well-tolerated and demonstrated non-inferior immunogenicity when administered to MCC vaccine-primed and vaccine-naïve toddlers.

Study of different routes of immunization using outer membrane vesicles of Neisseria meningitidis B and comparison of two adjuvants

Outer membrane vesicles (OMVs) of Neisseria meningitidis contain important antigens to trigger an immune response against meningococci and have been studied as vaccines compounds. The immune response to a vaccine may be affected by its constitution and route of administration. Therefore, Swiss mice were immunized by different routes with OMVs of N. meningitidis B with dimethyl dioctadecyl ammonium bromide in bilayer fragments (DDA-BF) or aluminum hydroxide (AH) as adjuvants. The adjuvants and different routes were compared regarding the immune responses by ELISA, western blot, delayed type hypersensitivity (DTH) and histopathologic analysis. The antigenic preparation generated humoral and cellular immune responses. In quantitative analyzes, in general, AH was superior to DDA-BF. However, analysis such as IgG avidity index, bactericidal activity and immunoblot, revealed no important differences regarding the adjuvant or route of immunization. Regarding the parameters tested, it was not possible to define a superiority between the adjuvants and routes of immunization proposed by this study.

Safety and Immunogenicity of a Quadrivalent Meningococcal Conjugate Vaccine in Healthy Meningococcal-Naïve Children 2-9 Years of Age: A Phase III, Randomized Study

BACKGROUND

Invasive meningococcal disease is a major cause of meningitis in children. An investigational meningococcal (serogroups A, C, Y, and W) tetanus toxoid conjugate vaccine (MenACYW-TT) could offer protection against invasive meningococcal disease in this population. This phase III study assessed the immunogenicity and safety of MenACYW-TT in children compared with a licensed quadrivalent meningococcal vaccine conjugated with diphtheria protein CRM197 (MenACWY-CRM).

METHODS

Healthy children 2-9 years of age in the United States, including Puerto Rico, were randomized (1:1) to receive MenACYW-TT (n = 499) or MenACWY-CRM (n = 501) (NCT03077438). Meningococcal antibody titers to the 4 vaccine serogroups were measured using a serum bactericidal antibody assay with human complement (hSBA) before and at day 30 after vaccination. Noninferiority between the vaccine groups was assessed by comparing seroresponse rates (postvaccination titers ≥1:16 when prevaccination titers were <1:8, or ≥4-fold increase if prevaccination titers were ≥1:8) to the 4 serogroups at day 30. Safety was monitored.

RESULTS

The proportion of participants achieving seroresponse at day 30 in the MenACYW-TT group was noninferior to the MenACWY-CRM group (A: 55.4% vs. 47.8%; C: 95.2% vs. 47.8%; W: 78.8% vs. 64.1%; Y: 91.5% vs. 79.3%, respectively). Geometric mean titers for serogroups C, W, and Y were higher with MenACYW-TT than for MenACWY-CRM. Both vaccines were well-tolerated and had similar safety profiles.

CONCLUSIONS

MenACYW-TT was well-tolerated in children and achieved noninferior immune responses to MenACWY-CRM against each of the 4 vaccine serogroups.

Influenza or Meningococcal Immunization During Pregnancy and Mortality in Women and Infants: A Pooled Analysis of Randomized Controlled Trials

This analysis includes pooled data from 2 placebo-controlled maternal influenza immunization trials, with a separate analysis on a meningococcal conjugate vaccine-controlled maternal influenza immunization trial. Maternal influenza immunization was not associated with infant or maternal all-cause mortality in placebo-controlled trials. In the meningococcal conjugate vaccine-controlled trial, there were fewer deaths during low or any influenza circulation weeks among infants whose mothers received meningococcal conjugate vaccine. ClinicalTrials.gov identifiers: NCT01430689, NCT01034254 and NCT02465190.

Characteristics of Neisseria Species Colonized in the Human’s Nasopharynx

Context: Neisseria meningitidis is the causative agent of a life-threatening infection with high mortality and morbidity worldwide. The most common types of this bacterium are serogroups A, B, C, W135, X, and Y. Although in some countries, such as Iran, the meningococcal meningitis has been well monitored and controlled by the use of divalent and quadrivalent vaccines, other fatal infections caused by these bacteria are still an important threat. For the above reason, this review focused on the differences of Neisseria characteristics, particularly in capsular composition, pathogenic and commensal stages to a better understanding of how to manage Neisseria infections. Evidence Acquisition: In this review, PubMed, EMBASE, ScienceDirect, Scopus, and Google Scholar were searched for English-language publications on pathogenic or commensal strains of Neisseria, meningococcal disease, Neisseria biology, genetic diversity, molecular typing, serogroups, diagnostic, and epidemiology around the world up to July 2019. All articles and academic reports in the defined area of this research were considered too. The data were extracted and descriptively discussed. Results: We included 85 studies in the survey. The data analysis revealed that the distribution of meningococcal serogroups was different regionally. For example, the serogroups C and W-135 accounted for Africa and Latin America regions, serogroup B in the European countries, and rarely in the Western Pacific, and serogroups A and C were dominant in Asian countries. Although data set for laboratory-based diagnosis of N. meningitidis are available for all countries, only 30% of the countries rely on reference laboratories for serogroup determination, and more than half of the countries lack the ability of surveillance system. Nevertheless, molecular detection procedure is also available for all countries. The use of the meningococcal vaccine is a variable country by country, but most countries have applied the meningococcal vaccine, either divalent or quadrivalent, for the protection of high-risk groups. Conclusions: Owing to the geographical distribution of N. meningitidis serogroups in circulating, each country has to monitor for changes in serogroups diversity and its control management. Furthermore, laboratories should scale up the epidemiology and disease burden. It should be mentioned that quadrivalent meningococcal vaccines reduce the meningococcal disease burden sharply.

Neisseria meningitidis: analysis of pili and LPS in emerging Brazilian strains

BACKGROUND

Neisseria meningitidis is the main cause of bacterial meningitis in Brazil, where the main serogroups isolated are B and C; however, the serogroup W has recently emerged. LPS and type IV pili are important virulence factors that increase meningococci pathogenicity.

METHODS

The characterization of Lipopolysaccharide (LPS) and type IV pili in 19 meningococci strains of serogroup B, 21 of serogroup C, 45 of serogroup W and 28 of serogroup Y, isolated in Brazil between 2011 and 2017, was conducted using the Enzyme-linked Immunosorbent Assay (Dot- ELISA) technique and monoclonal antibodies.

RESULTS

We would like to emphasize the importance of characterizing relevant antigens, such as pili and LPS, the use of monoclonal antibodies to support it, and how such studies improve vaccine development and monitoring. Most of the strains studied presented L3,7,9 LPS and type IV pili; both antigens are associated with the capacity to cause invasive disease.

CONCLUSION

Due to the impact of meningococcal disease, it is important to maintain and improve vaccine studies. Epitopes characterization provides data about the virulence of circulating strains. The use of monoclonal antibodies and serological techniques are relevant and support vaccine development.

Novel technology for storage and distribution of live vaccines and other biological medicines at ambient temperature

A novel, thin-film platform that preserves live viruses, bacteria, antibodies, and enzymes without refrigeration for extended periods of time is described. Studies with recombinant adenovirus in an optimized formulation that supports recovery of live virus through 16 freeze-thaw cycles revealed that production of an amorphous solid with a glass transition above room temperature and nitrogen-hydrogen bonding between virus and film components are critical determinants of stability. Administration of live influenza virus in the optimized film by the sublingual and buccal routes induced antibody-mediated immune responses as good as or better than those achieved by intramuscular injection. This work introduces the possibility of improving global access to a variety of medicines by offering a technology capable of reducing costs of production, distribution, and supply chain maintenance.

Costs of Invasive Meningococcal Disease: A Global Systematic Review

BACKGROUND

Invasive meningococcal disease remains a public health concern because of its rapid onset and significant risk of death and long-term disability. New meningococcal serogroup B and combination serogroup ACWY vaccines are being considered for publicly funded immunization programs in many countries. Contemporary costing data associated with invasive meningococcal disease are required to inform cost-effectiveness analyses.

OBJECTIVE

The objective of this study was to estimate costs and resource utilization associated with acute infection and the long-term care of invasive meningococcal disease.

DATA SOURCES AND METHODS

PubMed, EMBASE, The Cochrane Library, health economic databases, and electronically available conference abstracts were searched. Studies reporting any costs associated with acute infection and long-term sequelae of invasive meningococcal disease in English were included. All costs were converted into purchasing power parity-adjusted estimates [international dollars (I$)] using the Campbell and Cochrane Economics Methods Group and the Evidence for Policy and Practice Information and Coordinating Centre cost converter.

RESULTS

Fourteen studies met our eligibility criteria and were included. The mean costs of acute admission ranged from I$1629 to I$50,796, with an incremental cost of I$16,378. The mean length of hospital stay was reported to be 6-18 days in multiple studies. The average costs reported for readmissions ranged from I$7905 to I$15,908. Key variables such as the presence of sequelae were associated with higher hospitalization costs and longer inpatient stay. No studies estimated direct non-healthcare costs and productivity loss. Ten studies reported only unadjusted mean values without using appropriate statistical methods for adjustment.

CONCLUSIONS

Invasive meningococcal disease can result in substantial costs to healthcare systems. However, costing data on long-term follow-up and indirect costs used to populate health economic models are lacking.