Rationale for the Development of a Pentavalent Meningococcal Vaccine: A US-Focused Review

Invasive Meningococcal Disease in Children: Outcomes and Risk Factors for Sequelae and Fatal Cases in Greece

Invasive meningococcal disease (IMD) remains a major public health challenge due to its rapid progression, which may lead to severe sequelae or death in children and adolescents. Published data on IMD sequelae are limited in Greece and many EU countries. In the present study, patients under 16 years of age with IMD were retrospectively identified from the files of the Hellenic National Meningitis Reference Laboratory (HNML) from 2010-2020, and their medical records were tracked from the corresponding hospitals. Demographic, clinical, and microbiological data were recorded for each case. A total of 161 patients younger than 16 years of age admitted to nine hospitals across the country were identified. Of those, 91 (56.5%) records were found. The patients' median age was 36 months (range 22 days to 16 years old); 37.4% presented with meningitis, 36.2% with both septicemia and meningitis, and 26.4% only with septicemia. The mortality rate was 5.5% and was significantly associated with septicemia, abnormal platelet count at presentation, ICU admission, and coagulation disorders, while sequelae were detected in 16.9% of patients upon discharge. Neisseria meningitidis serogroup B (MenB) was the most predominant (77%); of these, 269 cc was identified (36.8%). This is the first study on unfavorable sequelae and mortality due to IMD performed in Greece.

Randomized trial showing persistence of hSBA titers elicited by a pentavalent meningococcal MenABCWY vaccine for up to 4 years following a primary series and safety and immunogenicity of a booster dose

BACKGROUND

Vaccination against 5 prominent meningococcal serogroups (A/B/C/W/Y) is necessary for broad disease protection. We report immunopersistence through 4 years after a 2-dose (6-month interval) pentavalent MenABCWY primary vaccine series and safety and immunogenicity of a booster administered 4 years after primary vaccination.

METHODS

This randomized, active-controlled, observer-blinded study was conducted in the United States and Europe. In stage 1, healthy MenACWY vaccine-naive or -experienced 10- to 25-year-olds were randomized 1:2 to receive MenABCWY and placebo or MenB-fHbp and MenACWY-CRM. Eligible participants were randomly selected to participate in stage 2, which was an open-label immunopersistence and booster extension. Immunogenicity was assessed through serum bactericidal antibody using human complement (hSBA) assays with serogroups A/C/W/Y (MenA/C/W/Y) and 4 primary serogroup B (MenB) test strains. Immunogenicity endpoints included hSBA seroprotection rates through 48 months after primary vaccination and 1 month after the booster. Safety endpoints included booster reactogenicity events and adverse events (AEs).

RESULTS

Of 1379 eligible participants, 353 entered stage 2; 242 completed the 48-month blood draw after primary vaccination and 240 completed the booster vaccination phase. MenA/C/W/Y seroprotection rates remained high for 4 years following a 2-dose MenABCWY primary series (MenACWY-naive, 62.0 %-100.0 %; MenACWY-experienced, 98.7 %-100.0 %) and trended higher than those after a single MenACWY-CRM dose (MenACWY-naive, 38.1 %-95.2 %; MenACWY-experienced, 89.7 %-100.0 %). Corresponding seroprotection rates against MenB remained stable and generally higher than baseline (MenABCWY, 18.2 %-36.6 %; MenB-fHbp, 16.2 %-31.9 % across strains). Following a booster, seroprotection rates against all 5 serogroups were ≥ 93.8 % across groups. Most booster dose reactogenicity events were mild or moderate in severity, and AEs were infrequent.

CONCLUSIONS

Immune responses remained high for MenA/C/W/Y and above baseline for MenB through 4 years after the MenABCWY primary series, with robust responses for all 5 serogroups observed following a booster. The MenABCWY booster had an acceptable safety and tolerability profile consistent with the primary series. NCT03135834.

Whole-genome sequencing of Neisseria meningitidis collected in Chile from pediatric patients during 2016-2019 and coverage vaccine prediction

BACKGROUND

Over the past few years, whole-genome sequencing (WGS) has become a valuable tool for global meningococcal surveillance. The objective of this study was to genetically characterize Neisseria meningitidis strains isolated from children in Chile through WGS and predicting potential vaccine coverage using gMATS and MenDeVAR.

METHODS

WGS of 42 N.meningitidis from pediatric patients were processed and assembled using different software. We analyzed genomes with BIGSdb platform hosted at PubMLST.org, and predicted vaccine coverage using MenDeVAR and gMATS tools.

RESULTS

Among 42 strains, 25 were MenB, 16 MenW, and 1 MenC. The cc11 and cc 41/44 were the most frequents. The main frequent deduced peptide sequence for PorA was P1.5,2 (40 %), peptide P1.4 was present in one MenB strain; NHBA-29 (64 %), none having peptide 2; fHbp-2 (76 %), one strain had peptide-1, and two had peptide 45; NadA was detected in 52 %, peptide-6 was present in 84 %, none had peptide 8. The MenDeVAR index predicted a coverage in MenB strains for 4CMenB 8 % exact matches, 12 % cross-reactivity, 8 % not coverage and 64 % had insufficient data. gMATS predicted 16 % was covered, 8 % not covered and 76 % unpredictable, and overall coverage of 54 %. For rLP2086-fHbp, the MenDeVAR index predicted exact match in 8 %, cross-reactivity in 64 %, and insufficient data in 28 % and an overall coverage of 72 %. In non-MenB strains, the MenDeVAR index predicted for 4CMenB vaccine: cross-reactivity 88 %, 6 % for not covered and insufficient data. For rLP2086-fHbp, predicted cross-reactivity 12 % and insufficient data in 88 %. gMATS predicted an overall coverage of 50 % for Non-MenB.

CONCLUSION

genetic variability of the Chilean strains that its different from other countries, and until now limit the coverage prediction of vaccine with the available tools like gMATS and MenDeVAR.

Global Epidemiology of Meningococcal Disease-Causing Serogroups Before and After the COVID-19 Pandemic: A Narrative Review

Invasive meningococcal disease (IMD) is associated with high morbidity and mortality and predominantly caused by five Neisseria meningitidis serogroups (A/B/C/W/Y). Polysaccharide conjugate vaccines induce T-cell-dependent immune responses, are immunogenic in infants and adults, and reduce carriage, and vaccination of age groups associated with high-carriage can provide indirect protection in the unvaccinated (herd immunity). Successful vaccination programs must be tailored to local epidemiology, which varies geographically, temporally, and by age and serogroup. Serogroup A IMD once predominated globally, but has largely disappeared following mass vaccination programs. Serogroup B was a predominant cause of IMD in many global regions from 2010 to 2018, typically affecting younger age groups. Spread of serogroup C clonal complex-11 IMD in the 1990s prompted implementation of MenC vaccine programs in many countries, resulting in declines in prevalence. Serogroup C still caused > 20% of global IMD through the mid-2010s. Serogroup W became a significant contributor to global IMD after Hajj pilgrimage outbreaks in 2000; subsequent increases of endemic disease and outbreaks were reported pre-pandemic in many regions. Serogroup Y emerged in the 1990s as a significant cause of IMD throughout various regions and prevalence had increased or stabilized from 2010 to 2018. Serogroup X is uncommon outside the African meningitis belt, and its prevalence has declined since before the COVID-19 pandemic. Global IMD declines during the pandemic were followed by resurgences generally caused by serogroups that were prevalent pre-pandemic and affecting mainly unvaccinated age groups (particularly adolescents/young adults). Recent IMD epidemiology underscores the importance of vaccinating at-risk age groups against regionally prevalent serogroups; for example, the anti-serogroup X component of the recently prequalified MenACWXY vaccine is likely to provide limited protection outside the African meningitis belt. In other regions, comprehensive vaccination against MenB and MenACWY, which could be streamlined by the recently approved MenABCWY vaccine, seems more appropriate.

Preferences of US adolescents and parents for vaccination against invasive meningococcal disease

BACKGROUND

Percentage uptake of some meningococcal vaccines is low in the US. Understanding what drives vaccination preferences may help to increase vaccination rates.

OBJECTIVES

To determine how attributes of meningococcal vaccines and the availability of a pentavalent (MenABCWY) vaccine profile drive adolescents' and young people's (AYP's) willingness to be vaccinated and parents' and legal guardians' (PLG') willingness for their child to be vaccinated (WTV). To also explore how preferences for meningococcal vaccines vary by participant characteristics.

METHODS

Vaccine preferences were elicited in a discrete choice experiment (DCE) with AYP aged 16-23 years and PLG of adolescents aged 11-17 years. Participants chose between two hypothetical vaccine profiles that differed in level of protection, dosing, and risks of mild-to-moderate and severe side effects, and a no vaccination profile. Main outcome measures were relative attribute importance (RAI) and WTV. RAI measured the maximum contribution of an attribute to vaccination choice relative to other attributes. WTV compared predicted choice probabilities for the three vaccine profiles.

RESULTS

407 AYP and 394 PLG participated (50.9% male, 78.4% White/Caucasian). Irrespective of vaccine attributes, 59.5% always opted into vaccination and 3.6% always opted out of vaccination. The most important attributes were level of protection (RAI: 33.7%) and risk of mild-to-moderate side effects (RAI: 32.3%). Dosing was more important to PLG (RAI: 5.9%) than AYP (RAI: 2.0%; p < .01). Adding a pentavalent vaccine alternative increased WTV by 3.7 percentage points (PP) for PLG, 2.4 PP for AYP, 16.4 PP for vaccine-hesitant participants, 13.4 PP for participants without health insurance, and 9.6 PP for adults.

CONCLUSION

Level of protection and risk of mild-to-moderate side effects were the most important vaccine attributes. Adding a pentavalent vaccine alternative increased WTV particularly among adults, individuals who were vaccine-hesitant, and individuals without health insurance.

Analytical Challenges in Novel Pentavalent Meningococcal Conjugate Vaccine (A, C, Y, W, X)

Multivalent meningococcal conjugate vaccines are a significant focus for the scientific community in light of the WHO's mission to defeat meningitidis by 2030. Well-known meningococcal vaccines such as MenAfriVac, Nimenrix, Menveo, and MenQuadfi are licensed in various parts of the world and have been successful. Recently, the World Health Organization (WHO) qualified MenFive (meningococcal A, C, Y, W, and X) conjugate vaccine, further enhancing the battery of vaccines against meningitis. The antigenic nature of the current and new serogroups, the selection of carrier proteins, and the optimal formulation of these biomolecules are pivotal parameters for determining whether a biological preparation qualifies as a vaccine candidate. Creating appropriate quality control analytical tools for a complex biological formulation is challenging. A scoping review aims to identify the main challenges and gaps in analyzing multivalent vaccines, especially in the case of novel serogroups, such as X, as the limited literature addresses these analytical challenges. In summary, the similarities in polysaccharide backbones between meningococcal serogroups (C, Y, W sharing a sialic acid backbone and A, X sharing a phosphorous backbone) along with various conjugation chemistries (such as CNBr activation, reductive amination, CDAP, CPIP, thioether bond formation, N-hydroxy succinimide activation, and carbodiimide-mediated coupling) resulting into a wide variety of polysaccharide -protein conjugates. The challenge in analyzing carrier proteins used in conjugation (such as diphtheria toxoid, tetanus toxoid, CRM diphtheria protein, and recombinant CRM) is assessing their purity (whether they are monomeric or polymeric in nature as well as their polydispersity). Additional analytical challenges include the impact of excipients, potential interference from serogroups, selection and establishment of standards, age-dependent behavior of biomolecules indicated by molecular size distributions, and process-driven variations. This article explains the analytical insights gained (polysaccharide content, free saccharide, free proteins, MSD) during the development of the MenFive vaccine and highlights the crucial gaps and challenges in testing.

Meningococcal Vaccination of Adolescents in the United States: Past Successes and Future Considerations

Invasive meningococcal disease (IMD) is a rare but serious illness, and adolescents and young adults in the United States are at increased risk. Here, we discuss US IMD history and how successful disease prevention through routine vaccination against the most common disease-causing serogroups (A, B, C, W, and Y) can inform future recommendations. Before the introduction of quadrivalent meningococcal conjugate (MenACWY) vaccines, most US cases of IMD were caused by serogroups B, C, and Y. After recommendation by the Advisory Committee on Immunization Practices for routine MenACWY vaccination of 11-12-year-olds in 2005, followed by a 2010 booster recommendation, MenCWY disease incidence declined dramatically, and vaccine coverage remains high. Two serogroup B (MenB) vaccines are licensed in the United States, but uptake is low compared with MenACWY vaccines, likely because Advisory Committee on Immunization Practices recommends MenB vaccination subject to shared clinical decision-making rather than routinely for all adolescents. The proportion of adolescent IMD caused by MenB has now increased. Pentavalent vaccines that protect against serogroups A, B, C, W, and Y may provide an optimal strategy for improving vaccination rates to ultimately reduce MenB incidence while maintaining the historically low rates of IMD caused by serogroups A, C, W, and Y.

Molecular size distribution in pentavalent (A, C, Y, W, X) meningococcal polysaccharide conjugate vaccine by HPSEC-UV-MALS-RI method- a conceivable stability indicating parameter

Molecular size distribution (MSD) of polysaccharides serves as a key parameter that directly correlates to the immunogenicity of vaccine. MSD at meningococcal polysaccharide (A, C, Y and W) or conjugate bulk level is well established under detailed pharmacopeial and WHO guidelines. We report here, a newly developed method for determination of molecular size distribution of pentavalent Meningococcal conjugate vaccine comprising of A, C, Y, W and X (MenFive). Although serogroup specific molecular size could not be estimated here; lot to lot consistency monitoring, molecular aggregates distribution in final lot, are key takeaways of this method. Determination of MSD in pentavalent fill finished product was quite challenging. Various columns/detectors combination, buffers, physico-chemical conditions (temperature, 2-8 °C, 25 °C, 40 °C and 60 °C; flow rate, 0.3 mL to 0.8 mL), liquid/lyophilized formulations, were explored. Polymer-based packed columns were explored for estimation for MSD by aqueous size exclusion chromatography, using combinations of- Shodex OHPAK SB 807 HQ, Shodex OHPAK SB 806 HQ, G6000 PWXL, coupled with guard Shodex OHPAK SB-G-6B. MenFive showed heterogenous distribution of molecules ranging from 200 to 19000 kDa, indicating its complex nature. However, 1000-8000 kDa was dominant range, comprising of ≥ 50 % distribution of molecules, in both liquid as well as lyophilized formulations, with average molecular weight around 6000-6500 kDa. The molar mass distribution after slicing would provide an insight to the conformation of molecules through its presentation as HMW, LMW, aggregates and subsequently, the presence of dominant population of molecules of a particular molecular weight and its total contribution in the sample.

The Diverse Spectrum of Invasive Meningococcal Disease in Pediatric and Adolescent Patients: Narrative Review of Cases and Case Series

INTRODUCTION

Invasive meningococcal disease (IMD) is a potentially life-threatening disease caused by Neisseria meningitidis infection. We reviewed case reports of IMD from newborns, infants, children, and adolescents, and described the real-life clinical presentations, diagnoses, treatment paradigms, and clinical outcomes.

METHODS

PubMed and Embase were searched for IMD case reports on patients aged ≤ 19 years published from January 2011 to March 2023 (search terms "Neisseria meningitidis" or "invasive meningococcal disease", and "infant", "children", "paediatric", pediatric", or "adolescent").

RESULTS

We identified 97 publications reporting 184 cases of IMD, including 25 cases with a fatal outcome. Most cases were in adolescents aged 13-19 years (34.2%), followed by children aged 1-5 years (27.6%), children aged 6-12 years (17.1%), infants aged 1-12 months (17.1%), and neonates (3.9%). The most common disease-causing serogroups were W (40.2%), B (31.7%), and C (10.4%). Serogroup W was the most common serogroup in adolescents (17.2%), and serogroup B was the most common in the other age groups, including children aged 1-5 years (11.5%). The most common clinical presentations were meningitis (46.6%) and sepsis (36.8%).

CONCLUSIONS

IMD continues to pose a threat to the health of children and adolescents. While this review was limited to case reports and is not reflective of global epidemiology, adolescents represented the largest group with IMD. Additionally, nearly half of the patients who died were adolescents, emphasizing the importance of monitoring and vaccination in this age group. Different infecting serogroups were predominant in different age groups, highlighting the usefulness of multivalent vaccines to provide the broadest possible protection against IMD. Overall, this review provides useful insights into real-life clinical presentations, treatment paradigms, diagnoses, and clinical outcomes to help clinicians diagnose, treat, and, ultimately, protect patients from this devastating disease.

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.

Antibody persistence and revaccination recommendations of MenACWY-TT: a review of clinical studies assessing antibody persistence up to 10 years after vaccination

INTRODUCTION

Invasive meningococcal disease (IMD) is potentially fatal and associated with severe sequelae among survivors. It is preventable by several vaccines, including meningococcal vaccines targeting the most common disease-causing serogroups (A, B, C, W, Y). The meningococcal ACWY tetanus toxoid conjugate vaccine (MenACWY-TT [Nimenrix]) is indicated from 6 weeks of age in the European Union and >50 additional countries.

AREAS COVERED

Using PubMed, Google Scholar, ClinicalTrials.gov and ad hoc searches for publications to June 2023, we review evidence of antibody persistence for up to 10 years after primary vaccination and up to 6 years after MenACWY-TT revaccination. We also review global MenACWY revaccination recommendations and real-world impact of vaccination policies, focusing on how these data can be considered alongside antibody persistence data to inform future IMD prevention strategies.

EXPERT OPINION

Based on clear evidence that immunogenicity data (demonstrated antibody titers above established correlates of protection) are correlated with real-world effectiveness, long-term persistence of antibodies after MenACWY-TT vaccination suggests continuing protection against IMD. Optimal timing of primary and subsequent vaccinations is critical to maximize direct and indirect protection. Recommending bodies should carefully consider factors such as age at vaccination and long-term immune responses associated with the specific vaccine being used.

The important lessons lurking in the history of meningococcal epidemiology

INTRODUCTION

The epidemiology of invasive meningococcal disease (IMD), a rare but potentially fatal illness, is typically described as unpredictable and subject to sporadic outbreaks.

AREAS COVERED

Meningococcal epidemiology and vaccine use during the last ~ 200 years are examined within the context of meningococcal characterization and classification to guide future IMD prevention efforts.

EXPERT OPINION

Historical and contemporary data highlight the dynamic nature of meningococcal epidemiology, with continued emergence of hyperinvasive clones and affected regions. Recent shifts include global increases in serogroup W disease, meningococcal antimicrobial resistance (AMR), and meningococcal urethritis; additionally, unvaccinated populations have experienced disease resurgences following lifting of COVID-19 restrictions. Despite these changes, a close analysis of meningococcal epidemiology indicates consistent dominance of serogroups A, B, C, W, and Y and elevated IMD rates among infants and young children, adolescents/young adults, and older adults. Demonstrably effective vaccines against all 5 major disease-causing serogroups are available, and their prophylactic use represents a powerful weapon against IMD, including AMR. The World Health Organization's goal of defeating meningitis by the year 2030 demands broad protection against IMD, which in turn indicates an urgent need to expand meningococcal vaccination programs across major disease-causing serogroups and age-related risk groups.

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.

Determinants of Meningococcal Vaccination Coverage and Adherence: A Targeted Literature Review Supporting a 16-year-old Healthcare Visit

We conducted a targeted literature review to understand the determinants of meningococcal serogroups A, C, W, and Y (MenACWY) and meningococcal serogroup B (MenB) vaccination coverage and adherence to vaccination schedules in the USA, and to identify evidence to support improvement of MenACWY and MenB vaccination coverage and adherence in older adolescents. Sources published since 2011 were considered, with sources published since 2015 given preference. Out of 2355 citations screened, 47 (46 studies) were selected for inclusion. Determinants of coverage and adherence ranging from patient-level sociodemographic factors to policy-level factors were identified. Four determinants identified were associated with improved coverage and adherence: (1) well-child, preventive, or vaccination-only appointments (particularly for older adolescents); (2) provider-initiated, provider-driven vaccine recommendations; (3) provider education about meningococcal disease and vaccine recommendations; and (4) state-level school-entry immunization policies. This robust review of the literature sheds light on the continued low MenACWY and MenB vaccination coverage and adherence among older adolescents (16-23 years of age) compared with that of younger adolescents (11-15 years of age) in the USA. The evidence supports a renewed call to action by local and national health authorities and medical organizations urging healthcare professionals to implement a healthcare visit for 16-year-olds and focus on vaccination as a key component of the visit.

Immunization of Solid Organ Transplant Candidates and Recipients: A 2022 Update

Immunizations are a relatively safe and cost-effective intervention to prevent morbidity and mortality associated with vaccine preventable infection (VPIs). As such, immunizations are a critical part of the care of pre and posttransplant patients and should be prioritized. New tools are needed to continue to disseminate and implement the most up-to-date vaccine recommendations for the SOT population. These tools will help both primary care providers and multi-disciplinary transplant team members taking care of transplant patients to stay abreast of evidence-based best practices regarding the immunization of the SOT patient.

Expert Perspectives on the Vaccination of Individuals Who Are at Increased Risk of Meningococcal Disease Due to Medical Conditions: A Podcast

Patients with functional or anatomic asplenia, including sickle cell anemia; complement component deficiency; or human immunodeficiency virus (HIV) infection have a significantly increased risk of developing meningococcal disease. The Advisory Committee on Immunization Practices (ACIP) of the Centers for Disease Control and Prevention (CDC) recommends vaccination with a quadrivalent meningococcal conjugate vaccine against serogroups A, C, W, and Y (MenACWY) for individuals 2 months of age or older who are diagnosed with functional or anatomic asplenia, complement component deficiency, or HIV infection. Vaccination with a meningococcal vaccine against serogroup B (MenB) is also recommended for individuals 10 years of age or older who are diagnosed with functional or anatomic asplenia or complement component deficiency. Despite these recommendations, recent studies have shown that vaccination coverage in these populations is low. In this podcast, the authors discuss the challenges for implementing vaccine recommendations for individuals with medical conditions at increased risk of developing meningococcal disease and discuss strategies to increase coverage. Suboptimal vaccination rates could be addressed by better educating healthcare providers about recommendations for MenACWY and MenB vaccines in individuals at increased risk, increasing awareness of low vaccination coverage, and tailoring the education to the needs of particular healthcare providers and their respective patient populations. Barriers to vaccination could also be removed by administering vaccines at alternative sites of care, bundling preventative services, and implementing vaccination reminder systems that are tied to immunization information systems.

The Impact of Social Determinants of Health on Meningococcal Vaccination Awareness, Delivery, and Coverage in Adolescents and Young Adults in the United States: A Systematic Review

Vaccines remain a fundamental intervention for preventing illness and death. In the United States, suboptimal vaccine uptake in adolescents and young adults has been observed for meningococcal conjugate (MenACWY) and serogroup B meningococcal (MenB) vaccines, particularly among marginalized communities, despite current recommendations by the Advisory Committee on Immunization Practices. A systematic literature search was conducted in the MEDLINE and MEDLINE In-Process, Embase, Cochrane, PsychInfo, and CINAHL databases to identify both drivers of, and barriers to, MenACWY and MenB vaccine uptake in adolescents and young adults. A total of 34 of 46 eligible studies that presented outcomes stratified by race/ethnicity, geography, and socioeconomic status were selected for review. Results showed MenACWY and MenB vaccination coverage in adolescents and young adults is impacted by racial/ethnic, socioeconomic, and geographic disparities. Gaps also exist in insurance for, or access to, these vaccines in adolescents and young adults. Moreover, there was variability in the understanding and implementation of the shared decision-making recommendations for the MenB vaccine. Disease awareness campaigns, increased clarity in accessing all meningococcal vaccines, and further research on the relationships between measures of marginalization and its impact on vaccine coverage in adolescents and young adults are needed to reduce the incidence of severe infections.

Use of expanded Neisseria meningitidis serogroup B panels with the serum bactericidal antibody assay for the evaluation of meningococcal B vaccine effectiveness

INTRODUCTION

Neisseria meningitidis serogroup B (NmB) antigens are inherently diverse with variable expression among strains. Prediction of meningococcal B (MenB) vaccine effectiveness therefore requires an assay suitable for use against large panels of epidemiologically representative disease-causing NmB strains. Traditional serum bactericidal antibody assay using exogenous human complement (hSBA) is limited to the quantification of MenB vaccine immunogenicity on a small number of indicator strains.

AREAS COVERED

Additional and complementary methods for assessing strain coverage developed previously include the Meningococcal Antigen Typing System (MATS), Meningococcal Antigen Surface Expression (MEASURE) assay, and genotyping approaches, but these do not estimate vaccine effectiveness. We provide a narrative review of these methods, highlighting a more recent approach involving the hSBA assay in conjunction with expanded NmB strain panels: hSBA assay using endogenous complement in each vaccinated person's serum (enc-hSBA) against a 110-strain NmB panel and the traditional hSBA assay against 14 (4 + 10) NmB strains.

EXPERT OPINION

The enc-hSBA is a highly standardized, robust method that can be used in clinical trials to measure the immunological effectiveness of MenB vaccines under conditions that mimic real-world settings as closely as possible, through the use of endogenous complement and a diverse, epidemiologically representative panel of NmB strains.