Reduced schedules of 4CMenB vaccine in infants and catch-up series in children: Immunogenicity and safety results from a randomised open-label phase 3b trial

Lifecycle model-based evaluation of infant 4CMenB vaccination in the UK

OBJECTIVES

Invasive meningococcal disease, an uncommon but severe disease, imposes catastrophic health and economic burdens. Cost-utility analysis (CUA) assumes separability in lifetime health and economic variables and cannot capture the full value of preventing such burdens. We overcome these limitations with a retrospective societal perspective cost-benefit analysis (CBA) of meningococcal serogroup B vaccination (4CMenB) of one infant cohort in the United Kingdom using a health-augmented lifecycle model (HALM) incorporating health's interactions with consumption, earnings, non-market time and financial risk.

METHODS

We used a static Markov model of vaccination's health impact and an HALM to estimate the private willingness to pay (PWTP) for the intrinsic and instrumental value of health under perfect capital markets, financial risk protection in the absence of insurance against permanent disability, parental spillovers, and acute phase disability. We estimated social WTP (SWTP) incorporating social severity preferences. We estimated rates of return that inform health payer reimbursement decisions, finance ministry budgeting decisions, and legislature taxation decisions. An expert Advisory Board investigated the validity of applying the HALM to infant 4CMenB.

RESULTS

The PWTP for a 2 + 1 vaccination schedule is £395, comprising £166 of disability insurance value, £79 of positive parental spillover value, £28 in the value of averting acute phase disability, and £122 in residual intrinsic and instrumental value of health. SWTP is £969.

CONCLUSIONS

HALM-based CBA provides an empirically richer, more utility-theoretically grounded approach to vaccine evaluation than CUA, demonstrating good value for money for legislatures (based on private values) and for all decision-makers (based on social values).

Effectiveness of a Meningococcal Group B Vaccine (4CMenB) in Children

BACKGROUND

In September 2015, the four-component, protein-based meningococcal serogroup B vaccine (4CMenB; Bexsero) became available for private purchase in Spain.

METHODS

We conducted a nationwide matched case-control study to assess the effectiveness of 4CMenB in preventing invasive meningococcal disease in children. The study included all laboratory-confirmed cases of invasive meningococcal disease in children younger than 60 months of age between October 5, 2015, and October 6, 2019, in Spain. Each case patient was matched with four controls according to date of birth and province. 4CMenB vaccination status of the case patients and controls was compared with the use of multivariate conditional logistic regression.

RESULTS

We compared 306 case patients (243 [79.4%] with serogroup B disease) with 1224 controls. A total of 35 case patients (11.4%) and 298 controls (24.3%) had received at least one dose of 4CMenB. The effectiveness of complete vaccination with 4CMenB (defined as receipt of at least 2 doses, administered in accordance with the manufacturer's recommendations) was 76% (95% confidence interval [CI], 57 to 87) against invasive meningococcal disease caused by any serogroup, and partial vaccination was 54% (95% CI, 18 to 74) effective. Complete vaccination resulted in an effectiveness of 71% (95% CI, 45 to 85) against meningococcal serogroup B disease. Vaccine effectiveness with at least one dose of 4CMenB was 64% (95% CI, 41 to 78) against serogroup B disease and 82% (95% CI, 21 to 96) against non-serogroup B disease. With the use of the genetic Meningococcal Antigen Typing System, serogroup B strains that were expected to be covered by 4CMenB were detected in 44 case patients, none of whom had been vaccinated.

CONCLUSIONS

Complete vaccination with 4CMenB was found to be effective in preventing invasive disease by serogroup B and non-serogroup B meningococci in children younger than 5 years of age.

Immunogenicity of a single 4CMenB vaccine booster in adolescents 11 years after childhood immunisation

The clinical development of the meningococcal vaccine, 4CMenB, included 2 doses in vaccine-naïve adolescents, which was considered unlikely to be cost-effective for implementation. Theoretically, priming with 4CMenB in early childhood might drive strong immune responses after only a single booster dose in adolescents and reduce programmatic costs. To address this question, children over 11 years old who took part in previous trials involving the administration of 3-5 doses of 4CMenB at infant/preschool age from 2006 were recruited into a post licensure single-centre trial, and were divided into two groups: those who received their last dose at 12 months old (infant group) and those who received their last dose at 3 years old (infant + preschool group). Naïve age-matched controls were randomised to receive one (adolescent 1 group) or two doses at days 0 and 28 (adolescent 2 group) of 4CMenB. Serum bactericidal antibody (SBA) assays using human complement were performed against three reference strains prior to vaccination, and at 1, 6 and 12 months. Previous vaccination was associated with a higher response to a single booster dose at 11 years of age, one-month post-vaccination, when compared with a single dose in naïve age-matched controls. At day 180, the highest responses were observed in participants in the infant + preschool group against strain 5/99 (GMT 316.1 [CI 158.4 to 630.8]), as compared with naïve adolescents who received two doses (GMTs 84.5 [CI 57.7 to 123.6]). When the last dose was received at 12-months of age, responses to a single adolescent dose were not as robust (GMT 61.1 [CI 14.8 to 252.4] to strain 5/99). This descriptive study indicates that the highest SBA responses after a single dose in adolescence were observed in participants who received a preschool dose, suggesting that B cell memory responses are not sufficiently primed at less than 12 months of age. Trial registration EudraCT 2017-004732-11, ISRCTN16774163.

Meningococcal Disease in Pediatric Age: A Focus on Epidemiology and Prevention

Meningococcal disease is caused by Neisseria meningitidis; 13 serogroups have been identified and differentiated from each other through their capsular polysaccharide. Serotypes A, B, C, W, X, and Y are responsible for nearly all infections worldwide. The most common clinical manifestations are meningitis and invasive meningococcal disease, both characterized by high mortality and long-term sequelae. The infection rate is higher in children younger than 1 year and in adolescents, who are frequently asymptomatic carriers. Vaccination is the most effective method of preventing infection and transmission. Currently, both monovalent meningococcal vaccines (against A, B, and C serotypes) and quadrivalent meningococcal vaccines (against serogroups ACYW) are available and recommended according to local epidemiology. The purpose of this article is to describe the meningococcal vaccines and to identify instruments that are useful for reducing transmission and implementing the vaccination coverage. This aim could be reached by switching from the monovalent to the quadrivalent vaccine in the first year of life, increasing vaccine promotion against ACYW serotypes among adolescents, and extending the free offer of the anti-meningococcal B vaccine to teens, co-administering it with others proposed in the same age group. Greater awareness of the severity of the disease and increased health education through web and social networks could represent the best strategies for promoting adhesion and active participation in the vaccination campaign. Finally, the development of a licensed universal meningococcal vaccine should be another important objective.

Inhibitors of Bacterial Extracellular Vesicles

Both Gram-positive and Gram-negative bacteria can secrete extracellular vesicles (EVs), which contain numerous active substances. EVs mediate bacterial interactions with their hosts or other microbes. Bacterial EVs play a double-edged role in infections through various mechanisms, including the delivery of virulence factors, modulating immune responses, mediating antibiotic resistance, and inhibiting competitive microbes. The spread of antibiotic resistance continues to represent a difficult clinical challenge. Therefore, the investigation of novel therapeutics is a valuable research endeavor for targeting antibiotic-resistant bacterial infections. As a pathogenic substance of bacteria, bacterial EVs have gained increased attention. Thus, EV inhibitors are expected to function as novel antimicrobial agents. The inhibition of EV production, EV activity, and EV-stimulated inflammation are considered potential pathways. This review primarily introduces compounds that effectively inhibit bacterial EVs and evaluates the prospects of their application.

Timing of meningococcal vaccination with 4CMenB (Bexsero®) in children with invasive meningococcal group B (MenB) disease in England

BACKGROUND

Timely vaccination is critical for providing early protection against meningococcal B (MenB) disease because of the high incidence in early childhood. We assessed the timeliness of vaccination in children with confirmed MenB disease after 4CMenB (a recombinant protein-based vaccine) implementation into the national infant immunisation programme in England.

METHODS

Public Health England (PHE) conducts surveillance of invasive meningococcal disease (IMD) in England. Children born since 01 July 2015 who developed MenB disease between 01 September 2015 and 31 August 2019 (four surveillance years) were included in the analysis.

RESULTS

There were 276 children with laboratory-confirmed MenB disease, including 36 infants who were too young for vaccination, 59 who were eligible for one 4CMenB dose, 104 for two doses and 77 for 3 doses before they developed MenB disease. Prior to developing MenB disease, there were 59 opportunities for vaccination with two 4CMenB doses in 48/104 (46.5%) eligible infants and 41 opportunities in 28/77 (36.6%) children aged ≥ 1 year who were under-immunised. A schedule with a shorter interval at 8 and 12 weeks of age, compared to the current schedule at 8 and 16 weeks, had the potential to offer an additional 4CMenB dose to 35/58 infants (58.6%) who developed MenB disease between 10 and 18 weeks of age.

CONCLUSIONS

A high proportion of infants and toddlers with laboratory-confirmed MenB disease had not received their scheduled 4CMenB vaccine prior to developing MenB disease. An infant priming schedule with a shorter interval of 4 weeks has the potential to provide earlier protection against MenB disease.

Modeling the public health impact of different meningococcal vaccination strategies with 4CMenB and MenACWY versus the current toddler MenACWY National Immunization Program in Chile

Invasive meningococcal disease (IMD) is an uncommon yet unpredictable, severe, and life-threatening disease with the highest burden in young children. In Chile, most IMD is caused by meningococcal serogroup B (MenB) and W (MenW) infection. In response to a MenW outbreak in 2012, a toddler vaccination program was implemented using quadrivalent meningococcal conjugate vaccine against serogroups A, C, W and Y (MenACWY). The vaccine program, however, does not protect infants or other unvaccinated age groups and does not protect against MenB IMD. Since 2017, MenB IMD cases are becoming increasingly prevalent. Using a dynamic transmission model adapted for Chile, this analysis assessed the public health impact (reduction in IMD cases, long-term sequelae, deaths, and quality-adjusted life-years) of six alternative vaccination strategies using MenACWY and/or the four-component MenB (4CMenB) vaccine in infants, toddlers, and/or adolescents compared to the National Immunization Program (NIP) implemented in 2014. Strategies that added infant 4CMenB to MenACWY in toddlers or adolescents would prevent more IMD than the current NIP, observed within the first 5 years of the program. Replacing the NIP by an adolescent MenACWY strategy would prevent more IMD in the longer term, once herd immunity is established to protect unvaccinated infants or older age groups. The strategy that maximized reduction of IMD cases and associated sequelae in all age groups with immediate plus long-term benefits included infant 4CMenB and MenACWY in both toddlers and adolescents. This analysis can help policymakers determine the best strategy to control IMD in Chile and improve public health. A set of audio slides linked to this manuscript can be found at https://doi.org/10.6084/m9.figshare.16837543.

What is the context?

Invasive meningococcal disease (IMD) is a severe, sometimes fatal, unpredictable disease with highest rates in infants, young children, and adolescents. It is caused by different serogroups of Neisseria meningitidis bacteria. Most cases in Chile are due to meningococcal serogroups B (MenB) and W (MenW). Following a MenW IMD outbreak in 2012, vaccination was introduced, leading to the current National Immunization Program (NIP) in toddlers with quadrivalent meningococcal conjugate vaccine (MenACWY) (protecting against IMD caused by MenA, C, W, and Y).

What is new?

A disease model to predict the impact of vaccination strategies in the Chilean population compared six alternative strategies, using the multi-component MenB (4CMenB) vaccine for infants (protecting against MenB, with potential cross-protection against MenW and Y IMD) and/or the MenACWY vaccine for toddlers and/or adolescents.

What is the impact?

Results, compared to the NIP, show that: Strategy 1 (a program targeting only infants with 4CMenB) would reduce more MenB cases but fewer MenA, C, W and Y cases resulting in a lower reduction of total IMD cases in the long term; Strategy 3 (a program targeting only adolescents with MenACWY) would have a similar effect to the NIP in the short term but a far greater IMD reduction in the long term (as vaccinating this age group eventually reduces transmission to other age groups, reducing their risk of disease); all the other strategies targeted more than one age group, further reducing numbers of IMD cases compared with the NIP. The greatest benefits were seen with infant 4CMenB vaccination combined with toddler and adolescent MenACWY vaccination. Results can help policymakers determine the best IMD strategy to maximize the benefits of available meningococcal vaccines.

Public Health Impact and Cost-Effectiveness Analysis of Routine Infant 4CMenB Vaccination in Germany to Prevent Serogroup B Invasive Meningococcal Disease

Introduction

Invasive meningococcal disease (IMD) is an uncommon, severe, life-threatening disease primarily affecting infants, with potential lifelong sequelae. Neisseria meningitidis (Nm) serogroup B (MenB) causes most IMD cases in Germany, many of which can be prevented with four-component MenB (4CMenB) vaccination. The potential public health and economic impact of introducing routine 4CMenB infant vaccination in Germany was assessed.

Methods

A dynamic transmission-based cost-effectiveness model adapted for Germany assessed the impact of infant 4CMenB universal mass vaccination (UMV) versus no vaccination. The model included the latest real-world evidence on vaccine effectiveness, the comprehensive burden of disease on patients (sequelae) and their family (quality of life impact), comprehensive German IMD costs, and vaccination uptake assumptions.

Results

The largest public health impact was predicted in children: a rapid decline, 5 years after UMV implementation, of 39.9% (34.7%) for MenB (all IMD) cases aged 0–4 years and 42.4% (36.8%) in infants. Over lifetime (100-year time horizon), 4CMenB could prevent 3154 MenB (3303 all IMD) cases, 291 MenB (304 all IMD) deaths and 1370 MenB (1435 all IMD) long-term sequelae. 4CMenB saved 25,878 quality-adjusted life-years (QALYs), at a cost of €188,762 per QALY gained in the base case (societal perspective including lost productivity). Scenarios including potential Nm carriage protection (enabling herd protection) or societal preferences for the prevention of severe diseases led to more cost-effective results, while a scenario excluding IMD impact beyond the patient with increased discounting of vaccination health benefits produced less cost-effective results.

Conclusions

MenB IMD is a vaccine-preventable disease. This analysis for Germany can inform decision-makers on the potential impact of introducing infant 4CMenB UMV. The program is predicted to rapidly produce health benefits (reduction in child cases, deaths and sequelae) at a cost per QALY to society of around €190,000 (base case), decreasing to around €78,000 when considering societal preferences and IMD underreporting.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40121-021-00573-w.

Invasive meningococcal disease (IMD) is an uncommon but severe infection, usually presenting as meningitis and/or sepsis, caused by the bacteria Neisseria meningitidis. Most cases occur in infants, young children and adolescents. Patients who survive the disease can develop lifelong sequelae, such as physical, neurological and psychological/behavioural problems that impact their quality of life and that of their family/caregivers. This disease can be prevented by vaccination. The use of the four-component meningococcal serogroup B vaccine (4CMenB) in countries like Germany can prevent the most common form of this disease, IMD caused by serogroup B. This study assessed the public health and economic impact of infant vaccination in Germany with 4CMenB. For this, the authors used an economic model that measured the lifetime impact of the disease on patients but also on their families. The model predicted that after 5 years of vaccination, the number of cases and deaths in infants and young children aged 0–4 years would rapidly decrease by almost 40%. Over a long-term horizon of 100 years, this number was predicted to remain stable. Due to the reduced number of cases, vaccination would also result in fewer deaths and patients with sequelae, as well as cost savings for the healthcare system and society due to the reduced loss of productivity. In conclusion, in Germany, IMD caused by serogroup B is preventable through vaccination, and the 4CMenB vaccine in German infants is predicted to rapidly reduce the disease burden, save lives and prevent healthcare costs.

TIPICO XI: report of the first series and podcast on infectious diseases and vaccines (aTIPICO)

TIPiCO is an annual expert meeting and workshop on infectious diseases and vaccination. The edition of 2020 changed its name and format to aTIPiCO, the first series and podcasts on infectious diseases and vaccines. A total of 13 prestigious experts from different countries participated in this edition launched on the 26 November 2020. The state of the art of coronavirus disease-2019 (COVID-19) and the responsible pathogen, the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), and the options to tackle the pandemic situation were discussed in light of the knowledge in November 2020. Despite COVID-19, the status of other infectious diseases, including influenza infections, respiratory syncytial virus disease, human papillomavirus infection, measles, pertussis, tuberculosis, meningococcal disease, and pneumococcal disease, were also addressed. The essential lessons that can be learned from these diseases and their vaccines to use in the COVID-19 pandemic were also commented with the experts.

Translating meningococcal serogroup B vaccines for healthcare professionals

INTRODUCTION

Vaccination is an effective strategy to combat invasive meningococcal disease (IMD). Vaccines against the major disease-causing meningococcal serogroups are available; however, development of vaccines against serogroup B faced particular challenges, including the inability to target traditional meningococcal antigens (i.e. polysaccharide capsule) and limited alternative antigens due to serogroup B strain diversity. Two different recombinant, protein-based, serogroup B (MenB) vaccines that may address these challenges are currently available. These vaccines have been extensively evaluated in pre-licensure safety and immunogenicity trials, and recently in real-world studies on effectiveness, safety, and impact on disease burden.

AREAS COVERED

This review provides healthcare professionals, particularly pediatricians, an overview of currently available MenB vaccines, including development strategies and evaluation of coverage.

EXPERT OPINION

Overall, recombinant MenB vaccines are valuable tools for healthcare professionals to protect patients against IMD. Their development required innovative design approaches that overcame challenging hurdles and identified novel protein antigen targets; however, important distinctions in the approaches used in their development, evaluation, and administration exist and many unanswered questions remain. Healthcare providers frequently prescribing MenB vaccines are challenged to keep abreast of these differences to ensure patient protection against this serious disease.

Microbiota-host communications: Bacterial extracellular vesicles as a common language

Both gram-negative and gram-positive bacteria release extracellular vesicles (EVs) that contain components from their mother cells. Bacterial EVs are similar in size to mammalian-derived EVs and are thought to mediate bacteria–host communications by transporting diverse bioactive molecules including proteins, nucleic acids, lipids, and metabolites. Bacterial EVs have been implicated in bacteria–bacteria and bacteria–host interactions, promoting health or causing various pathologies. Although the science of bacterial EVs is less developed than that of eukaryotic EVs, the number of studies on bacterial EVs is continuously increasing. This review highlights the current state of knowledge in the rapidly evolving field of bacterial EV science, focusing on their discovery, isolation, biogenesis, and more specifically on their role in microbiota–host communications. Knowledge of these mechanisms may be translated into new therapeutics and diagnostics based on bacterial EVs.

Immunogenicity of the UK group B meningococcal vaccine (4CMenB) schedule against groups B and C meningococcal strains (Sched3): outcomes of a multicentre, open-label, randomised controlled trial

BACKGROUND

The use of the multicomponent meningococcal vaccine 4CMenB in the UK schedule at 2, 4, and 12 months of age has been shown to be 59·1% effective at preventing invasive group B meningococcal disease. Here, we report the first data on the immunogenicity of this reduced-dose schedule to help to interpret this effectiveness estimate.

METHODS

In this multicentre, parallel-group, open-label, randomised clinical trial, infants aged up to 13 weeks due to receive their primary immunisations were recruited via child health database mailouts in Oxfordshire and via general practice surgeries in Gloucestershire and Hertfordshire. Infants were randomly assigned (1:1) with permuted block randomisation to receive a 2 + 1 (2, 4, and 12 months; group 1) or 1 + 1 (3 and 12 months; group 2) schedule of the 13-valent pneumococcal conjugate vaccine (PCV13). All infants also received 4CMenB at 2, 4, and 12 months of age, and had blood samples taken at 5 and 13 months. Participants and clinical trial staff were not masked to treatment allocation. Proportions of participants with human complement serum bactericidal antibody (hSBA) titres of at least 4 were determined for group B meningococcus (MenB) reference strains 5/99 (Neisserial Adhesin A [NadA]), NZ98/254 (porin A), and 44/76-SL (factor H binding protein [fHbp]). Geometric mean titres (GMTs) with 95% CIs were also calculated, and concomitant vaccine responses (group C meningococcus [MenC], Haemophilus influenzae b [Hib], tetanus, diphtheria, and pertussis) were compared between groups. The primary outcome was PCV13 immunogenicity, with 4CMenB immunogenicity and reactogenicity as secondary outcomes. All individuals by randomised group with a laboratory result were included in the analysis. The study is registered on the EudraCT clinical trials database, 2015-000817-32, and ClinicalTrials.gov, NCT02482636, and is complete.

FINDINGS

Between Sept 22, 2015, and Nov 1, 2017, of 376 infants screened, 213 were enrolled (106 in group 1 and 107 in group 2). 204 samples post-primary immunisation and 180 post-boost were available for analysis. The proportion of participants with hSBA of at least 4 was similar in the two study groups. For strain 5/99, all participants developed hSBA titres above 4 in both groups and at both timepoints. For strain 44/76-SL, these proportions were 95·3% (95% CI 88·5-98·7) or above post-priming (82 of 86 participants in group 1), and 92·4% (84·2-97·2) or above post-boost (73 of 79 participants in group 1). For strain NZ98/254, these proportions were 86·5% (78·0-92·6) or above post-priming (83 of 96 participants in group 2) and 88·6% (79·5-94·7) or above post-boost (70 of 79 participants in group 1). The MenC rabbit complement serum bactericidal antibody (rSBA) titre in group 1 was significantly higher than in group 2 (888·3 vs 540·4; p=0·025). There was no significant difference in geometric mean concentrations between groups 1 and 2 for diphtheria, tetanus, Hib, and pertussis post-boost. A very small number of children did not have a protective response against 44/76-SL and NZ98/254. Local and systemic reactions were similar between the two groups, apart from the 3 month timepoint when one group received an extra dose of PCV13 and recorded more systemic reactions.

INTERPRETATION

These data support the recent change to the licensed European schedule for 4CMenB to add an infant 2 + 1 schedule, as used in the routine UK vaccine programme with an effectiveness of 59·1%. When compared with historical data, our data do not suggest that effectiveness would be higher with a 3 + 1 schedule, however a suboptimal boost response for bactericidal antibodies against vaccine antigen fHbp suggests a need for ongoing surveillance for vaccine breakthroughs due to fHbp-matched strains. Changing from a 2 + 1 to a 1 + 1 schedule for PCV13 for the UK is unlikely to affect protection against diphtheria, tetanus, and Hib, however an unexpected reduction in bactericidal antibodies against MenC seen with the new schedule suggests that ongoing surveillance for re-emergent MenC disease is important.

FUNDING

Bill & Melinda Gates Foundation and the National Institute for Health Research.

Understanding the reactogenicity of 4CMenB vaccine: Comparison of a novel and conventional method of assessing post-immunisation fever and correlation with pre-release in vitro pyrogen testing

BACKGROUND

Better understanding of vaccine reactogenicity is crucial given its potential impact upon vaccine safety and acceptance. Here we report a comparison between conventional and novel (continuous) methods of monitoring temperature and evaluate any association between reactogenicity and the monocyte activation test (MAT) employed for testing four-component capsular group B meningococcal vaccine (4CMenB) batches prior to release for clinical use in Europe.

METHODS

Healthy 7-12-week-old infants were randomised in two groups: group PCV13 2 + 1 (received pneumococcal conjugate vaccine 13 valent (PCV13) at 2, 4 and 12 months) and group PCV13 1 + 1 (received reduced schedule at 3 and 12 months). In both, infants received the remaining immunisations as per UK national schedule (including 4CMenB at 2, 4 and 12 months of age). Fever was measured for the first 24 h after immunisations using an axillary thermometer and with a wireless continuous temperature monitoring device (iButton®). To measure the relative pyrogenicity of individual 4CMenB batches, MAT was performed according to Ph. Eu. chapter 2.6.30 method C using PBMCs with IL-6 readout.

RESULTS

Fever rates detected by the iButton® ranged from 28.7% to 76.5% and from 46.6% to 71.1% in group PCV13 2 + 1 and PCV13 1 + 1 respectively, across all study visits. The iButton® recorded a higher number of fever episodes when compared with axillary measurements in both groups (range of axillary temperature fevers; group PCV13 2 + 1: 6.7%-38%; group PCV13 1 + 1: 11.4%-37.1%). An agreement between the two methods was between 0.39 and 0.36 (p < 0.001) at 8 h' time-point post primary immunisations. No correlation was found between MAT scores and fever rates, or other reported adverse events.

CONCLUSIONS

It is likely that conventional, intermittent, fever measurements underestimates fever rates following immunisation. 4CMenB MAT scores didn't predict reactogenicity, providing reassurance that vaccine batches with the highest acceptable pyrogen level are not associated with an increase in adverse events. Clinicaltrials.gov identifier: NCT02482636.

Gene expression profiling reveals insights into infant immunological and febrile responses to group B meningococcal vaccine

Neisseria meningitidis is a major cause of meningitis and septicaemia. A MenB vaccine (4CMenB) was licensed by the European Medicines Agency in January 2013. Here we describe the blood transcriptome and proteome following infant immunisations with or without concomitant 4CMenB, to gain insight into the molecular mechanisms underlying post-vaccination reactogenicity and immunogenicity. Infants were randomised to receive control immunisations (PCV13 and DTaP-IPV-Hib) with or without 4CMenB at 2 and 4 months of age. Blood gene expression and plasma proteins were measured prior to, then 4 h, 24 h, 3 days or 7 days post-vaccination. 4CMenB vaccination was associated with increased expression of ENTPD7 and increased concentrations of 4 plasma proteins: CRP, G-CSF, IL-1RA and IL-6. Post-vaccination fever was associated with increased expression of SELL, involved in neutrophil recruitment. A murine model dissecting the vaccine components found the concomitant regimen to be associated with increased gene perturbation compared with 4CMenB vaccine alone with enhancement of pathways such as interleukin-3, -5 and GM-CSF signalling. Finally, we present transcriptomic profiles predictive of immunological and febrile responses following 4CMenB vaccine.

Human Gut Commensal Membrane Vesicles Modulate Inflammation by Generating M2-like Macrophages and Myeloid-Derived Suppressor Cells

Immunomodulatory commensal bacteria modify host immunity through delivery of regulatory microbial-derived products to host cells. Extracellular membrane vesicles (MVs) secreted from symbiont commensals represent one such transport mechanism. How MVs exert their anti-inflammatory effects or whether their tolerance-inducing potential can be used for therapeutic purposes remains poorly defined. In this study, we show that MVs isolated from the human lactic acid commensal bacteria Pediococcus pentosaceus suppressed Ag-specific humoral and cellular responses. MV treatment of bone marrow-derived macrophages and bone marrow progenitors promoted M2-like macrophage polarization and myeloid-derived suppressor cell differentiation, respectively, most likely in a TLR2-dependent manner. Consistent with their immunomodulatory activity, MV-differentiated cells upregulated expression of IL-10, arginase-1, and PD-L1 and suppressed the proliferation of activated T cells. MVs' anti-inflammatory effects were further tested in acute inflammation models in mice. In carbon tetrachloride-induced fibrosis and zymosan-induced peritonitis models, MVs ameliorated inflammation. In the dextran sodium sulfate-induced acute colitis model, systemic treatment with MVs prevented colon shortening and loss of crypt architecture. In an excisional wound healing model, i.p. MV administration accelerated wound closure through recruitment of PD-L1-expressing myeloid cells to the wound site. Collectively, these results indicate that P. pentosaceus-derived MVs hold promise as therapeutic agents in management/treatment of inflammatory conditions.

Immunogenicity and Reactogenicity of a Reduced Schedule of a 4-component Capsular Group B Meningococcal Vaccine: A Randomized Controlled Trial in Infants

Background

The 4-component capsular group B meningococcal vaccine (4CMenB) was licensed as a 4-dose infant schedule but introduced into the United Kingdom as 3 doses at 2, 4, and 12 months of age. We describe the immunogenicity and reactogenicity of the 2 + 1 schedule in infants.

Methods

Infants were randomized to receive 4CMenB with routine immunizations (test group) at 2, 4, and 12 months or 4CMenB alone at 6, 8, and 13 months of age (control group). Serum bactericidal antibody (SBA) assay against a serogroup B meningococcal reference strain (44/76-SL), memory B-cell responses to factor H binding protein, Neisseria adhesion protein A, Neisseria heparin binding antigen, Porin A (PorA), and reactogenicity was measured.

Results

One hundred eighty-seven infants were randomized (test group: 94; control group: 93). In the test group, 4CMenB induced SBA titers above the putative protective threshold (1:4) after primary and booster doses in 97% of participants. Postbooster, the SBA GMT (72.1; 95% confidence interval [CI], 51.7-100.4) was numerically higher than the serum bactericidal antibody geometric mean titre (SBA GMT) determined post-primary vaccination (48.6; 95% CI, 37.2-63.4). After primary immunizations, memory B-cell responses did not change when compared with baseline controls, but frequencies significantly increased after booster. Higher frequency of local and systemic adverse reactions was associated with 4CMenB.

Conclusions

A reduced schedule of 4CMenB was immunogenic and established immunological memory after booster.

Isolation and Functions of Extracellular Vesicles Derived from Parasites: The Promise of a New Era in Immunotherapy, Vaccination, and Diagnosis

Experimental and epidemiological evidence shows that parasites, particularly helminths, play a central role in balancing the host immunity. It was demonstrated that parasites can modulate immune responses via their excretory/secretory (ES) and some specific proteins. Extracellular vesicles (EVs) are nano-scale particles that are released from eukaryotic and prokaryotic cells. EVs in parasitological studies have been mostly employed for immunotherapy of autoimmune diseases, vaccination, and diagnosis. EVs can carry virulence factors and play a central role in the development of parasites in host cells. These molecules can manipulate the immune responses through transcriptional changes. Moreover, EVs derived from helminths modulate the immune system via provoking anti-inflammatory cytokines. On the other hand, EVs from parasite protozoa can induce efficient immunity, that makes them useful for probable next-generation vaccines. In addition, it seems that EVs from parasites may provide new diagnostic approaches for parasitic infections. In the current study, we reviewed isolation methods, functions, and applications of parasite's EVs in immunotherapy, vaccination, and diagnosis.

Vaccination of Infants with Meningococcal Group B Vaccine (4CMenB) in England

BACKGROUND

In September 2015, the United Kingdom introduced the multicomponent meningococcal group B vaccine (4CMenB, Bexsero) into its publicly funded national immunization program at a reduced two-dose priming schedule for infants, with a 12-month booster.

METHODS

Using data from enhanced national surveillance of invasive meningococcal disease in England, we evaluated the effect of vaccination on the incidence of meningococcal group B disease during the first 3 years of the program. The effect of vaccination was assessed by comparing the observed incidence of disease with the expected incidence based on the incidence during the 4-year prevaccination period in equivalent cohorts and with the use of disease trends in cohorts of children younger than 5 years of age who were not eligible to receive the vaccine. Vaccine effectiveness was estimated with the use of the indirect screening method.

RESULTS

4CMenB uptake in England remained consistently high; data from the first 3 months of 2018 showed that 92.5% of children had completed the primary immunizations by their first birthday and 87.9% had received all three doses by 2 years. From September 2015 through August 2018, the incidence of meningococcal group B disease in England (average annual birth cohort, approximately 650,000 infants) was significantly lower in vaccine-eligible cohorts than the expected incidence (63 observed cases as compared with 253 expected cases; incidence rate ratio, 0.25; 95% confidence interval [CI], 0.19 to 0.36), with a 75% reduction in age groups that were fully eligible for vaccination. The adjusted vaccine effectiveness against meningococcal group B disease was 52.7% (95% CI, -33.5 to 83.2) with a two-dose priming schedule for infants and 59.1% (95% CI, -31.1 to 87.2) with a two-dose priming schedule plus a booster at 1 year). Over the 3-year period, there were 169 cases of meningococcal group B disease in the vaccine-eligible cohorts, and an estimated 277 cases (95% CI, 236 to 323) were prevented.

CONCLUSIONS

The 4CMenB program was associated with continued positive effect against meningococcal group B disease in children in England, and protection after three doses of the vaccine was sustained for at least 2 years. (Funded by Public Health England.).

Meningococcal Group B Vaccine For The Prevention Of Invasive Meningococcal Disease Caused By Neisseria meningitidis Serogroup B

Invasive meningococcal disease (IMD) is a major public health concern because of its high case fatality, long-term morbidity, and potential to course with outbreaks. IMD caused by Nesseira meningitidis serogroup B has been predominant in different regions of the world like Europe and only recently broadly protective vaccines against B serogroup have become available. Two protein-based vaccines, namely 4CMenB (Bexsero^®) and rLP2086 (Trumenba^®) are currently licensed for use in different countries against MenB disease. These vaccines came from a novel technology on vaccine design (or antigen selection) using highly specific antigen targets identified through whole-genome sequence analysis. Moreover, it has the potential to confer protection against non-B meningococcus and against other Neisserial species such as gonococcus. Real-world data on the vaccine-use are rapidly accumulating from the UK and other countries which used the vaccine for control of outbreak or as part of routine immunization program, reiterating its safety and efficacy. Additional data on real-life effectiveness, long-term immunity, and eventual herd effects, including estimates on vaccine impact for cost-effectiveness assessment are further needed. Given the predominance of MenB in Europe and other parts of the world, these new vaccines are crucial for the prevention and public health control of the disease, and should be considered.

Immunogenicity of the pneumococcal non-typeable Haemophilus influenzae protein D conjugate vaccine (PHiD-CV) administered concomitantly with the meningococcal serogroup B (4CMenB) vaccine in infants: A post-hoc analysis in a phase 3b, randomised, controlled trial

BACKGROUND

No data are currently available on immunogenicity of higher-valent pneumococcal conjugate vaccines when co-administered with a 4-component meningococcal serogroup B vaccine (4CMenB).

METHODS

Post-hoc analysis of pneumococcal non-typeable Haemophilus influenzae protein D conjugate vaccine (PHiD-CV) immunogenicity when co-administered with 4CMenB (2 + 1 schedule) and/or a CRM-conjugated meningococcal serogroup C vaccine (MenC-CRM) in a trial assessing 4CMenB reduced schedules and co-administration with MenC-CRM (NCT01339923). Infants were randomized to receive 4CMenB and MenC-CRM (Group 1) or MenC-CRM (Group 2) at 3, 5, and 12 months (M) of age. Both groups received PHiD-CV (3 + 1 schedule) as part of the Brazilian national immunisation programme at 3 M, 5 M, 7 M, and 12 M of age. Antibody responses were assessed pre-vaccination, 1 M post-dose 2, pre-booster, and 1 M post-booster.

RESULTS

Anti-pneumococcal antibody responses were in similar ranges in the two study groups.

CONCLUSIONS

4CMenB co-administration did not seem to impact antibody responses to PHiD-CV in infants.

Nephrotic syndrome following four-component meningococcal B vaccination: Epidemiologic investigation of a surveillance signal

BACKGROUND

In May 2014, a mass vaccination campaign with four-component meningococcal serogroup B (4CMenB) vaccine was launched in a localized region of Quebec, Canada experiencing high invasive meningococcal B disease endemicity. Active post-marketing surveillance identified several cases of nephrotic syndrome (NS) among ∼49,000 vaccinated individuals aged 2 months to 20 years. We report the epidemiologic investigation of this potential vaccine safety signal.

METHODS

Active vaccine safety surveillance was conducted electronically, with participants completing an online questionnaire prompted at 7 days after each dose and 6 months following the last dose. Additional NS cases were sought from provincial hospitalization and emergency room databases.

RESULTS

In the year following the first dose of 4CMenB vaccination, four confirmed NS cases (three hospitalized) were identified among vaccinated children 2-5-years-old with onset several months post-vaccination. None had renal biopsy but given their age, and positive response to steroids, idiopathic NS was presumptively diagnosed. Among vaccinated children 1-9-years-old, the NS incidence in the year post-vaccination was 17.7 per 100,000 (1 per 5650 vaccinees) with an NS hospitalization rate (i.e. excluding the outpatient case) that was 3.6-fold higher (95%CI = 0.7-11.8; p = 0.12) than the rest of the province for the same period, and 8.3-fold greater (95%CI = 1.1-62.0; p = 0.039) than during the eight years preceding the immunization campaign in the affected region.

CONCLUSION

Active safety surveillance identified an unexpected increase in NS incidence following 4CMenB vaccination. Further epidemiological investigation identified four vaccinated cases in total over a 12 month period of follow up. The greater risk in vaccinees had wide confidence intervals with he lower limit including or just above the nul value, an observation with no or marginal statistical significance. The temporal association with vaccination may be explained by other causes and/or chance clustering of a rare event unrelated to vaccination. To confirm or refute a potential link to vaccination, surveillance in other jurisdictions administering 4CMenB to children 1-9-years-old is needed.

Potential benefits of using a multicomponent vaccine for prevention of serogroup B meningococcal disease

Meningococcal serogroup B (MenB) has become the main cause of invasive meningococcal disease in industrialized countries in recent years. The diversity of MenB strains and poor immunogenicity of the MenB capsular polysaccharide have made vaccine development challenging. Two MenB vaccines, including factor H binding protein (fHbp) as a major antigenic component, are now licensed for use. In addition to fHbp variant 1, the multicomponent vaccine 4CMenB contains neisserial heparin binding antigen, Neisseria adhesin A, and outer membrane vesicles containing porin A. The vast majority of circulating MenB strains contain genes encoding at least one 4CMenB component and many express genes for more than one vaccine antigen. Recent studies have suggested that serum bactericidal activity is enhanced against strains that express two or more vaccine antigens. Bacterial killing may also occur when antibodies to vaccine components are collectively present at levels that would individually be sub-lethal. The evaluation of immune responses to separate vaccine components does not take cooperative activity into account and may underestimate the overall protection. Available data on 4CMenB effectiveness indicate that this multicomponent vaccine affords broad coverage and protection against MenB disease. 4CMenB also has the potential to protect against disease caused by non-MenB meningococci and Neisseria gonorrhoeae.

Antibody persistence and booster response in adolescents and young adults 4 and 7.5 years after immunization with 4CMenB vaccine

BACKGROUND

Data on duration of protection against invasive meningococcal disease post-vaccination with the recombinant, 4-component, meningococcal serogroup B vaccine (4CMenB) are limited. We evaluated bactericidal activity persistence in adolescents/young adults up to 7.5 years post-primary vaccination with 4CMenB, and response to a booster dose compared with vaccine-naïve controls.

METHODS

This open-label, multicenter study (NCT02446743) enrolled 15-24 year-old-previously vaccinated participants from Canada, Australia (group Primed_4y) 4 years post-priming with 4CMenB (2 doses; 0,1-month schedule), and Chile (Primed_7.5y) 7.5 years after priming with 4CMenB (2 doses; 0,1/0,2/0,6-month schedule) and vaccine-naïve participants of similar age (Naïve_4y and Naïve_7.5y groups). Primed participants received a booster dose; vaccine-naïve participants received 2 catch-up doses of 4CMenB, 1 month apart. We evaluated antibody persistence and immune responses using hSBA in terms of geometric mean titers and percentages of participants with hSBA titers ≥4, the kinetics of bactericidal activity post-booster (previously vaccinated) or post-2 doses (vaccine-naïve), and safety.

RESULTS

Antibody levels declined at 4 (Primed_4y) and 7.5 (Primed_7.5y) years post-primary vaccination, but remained higher than in vaccine-naïve participants at baseline (≤44% vs ≤ 13% [fHbp]; ≤84% vs ≤ 24% [NadA]; ≤29% vs ≤ 14% [PorA]) for all vaccine antigens except NHBA (≤81% vs ≤ 79%). One month post-booster and post-second dose, 93-100% of primed and 79-100% of vaccine-naïve participants had hSBA titers ≥4 for all antigens. Kinetics of the antibody response were similar across groups with an early robust response observed 7 days post-booster/second dose. No vaccine-related serious adverse event was reported.

CONCLUSION

For all antigens except NHBA, a higher proportion of primed participants had hSBA titers ≥4, at 4 and 7.5 years post-vaccination, compared with vaccine-naïve participants. A more robust immune response after booster compared to a first dose in vaccine-naïve individuals, showed effective priming in an adolescent/young adult population. No safety or new reactogenicity issues were identified.

Evaluation of strain coverage of the multicomponent meningococcal serogroup B vaccine (4CMenB) administered in infants according to different immunisation schedules

The 4-component vaccine 4CMenB, developed against invasive disease caused by meningococcal serogroup B, is approved for use in infants in several countries worldwide. 4CMenB is mostly used as 3 + 1 schedule, except for the UK, where a 2 + 1 schedule is used, and where the vaccine showed an effectiveness of 82.9%. Here we compared the coverage of two 4CMenB vaccination schedules (3 + 1 [2.5, 3.5, 5, 11 months] versus 2 + 1 [3.5, 5, 11 months of age]) against 40 serogroup B strains, representative of epidemiologically-relevant isolates circulating in England and Wales in 2007–2008, using sera from a previous phase 3b clinical trial. The strains were tested using hSBA on pooled sera of infants, collected at one month post-primary and booster vaccination. 4CMenB coverage was defined as the percentage of strains with positive killing (hSBA titres ≥ 4 after immunisation and negative baseline hSBA titres < 2). Coverage of 4CMenB was 40.0% (95% confidence interval [CI]: 24.9–56.7) and 87.5% (95%CI: 73.2–95.8) at one month post-primary and booster vaccination, respectively, regardless of immunisation schedule. Using a more conservative threshold (post-immunisation hSBA titres ≥ 8; baseline ≤ 2), at one month post-booster dose, strain coverages were 80% (3 + 1) and 70% (2 + 1). We used a linear regression model to assess correlation between post-immunisation hSBA data for each strain in the two groups; Pearson’s correlation coefficients were 0.93 and 0.99 at one month post-primary and booster vaccination. Overall, there is no evidence for a difference in strain coverage when 4CMenB is administered according to a 3 + 1 or 2 + 1 infant vaccination schedule.

Global epidemiology of serogroup B meningococcal disease and opportunities for prevention with novel recombinant protein vaccines

BACKGROUND

Meningococcal disease (MD) is a major cause of meningitis and sepsis worldwide, with a high case fatality rate and frequent sequelae. Neisseria meningitidis serogroups A, B, C, W, X and Y are responsible for most of these life-threatening infections, and its unpredictable epidemiology can cause outbreaks in communities, with significant health, social and economic impact. Currently, serogroup B is the main cause of MD in Europe and North America and one of the most prevalent serogroups in Latin America. Mass vaccination strategies using polysaccharide vaccines have been deployed since the 1970s and the use of conjugate vaccines has controlled endemic and epidemic disease caused by serogroups A, C, W and Y and more recently serogroup B using geographically-specific outer membrane vesicle based vaccines. Two novel protein-based vaccines are a significant addition to our armamentarium against N. meningitidis as they provide broad coverage against highly diverse strains in serogroup B and other groups. Early safety, effectiveness and impact data of these vaccines are encouraging. These novel serogroup B vaccines should be actively considered for individuals at increased risk of disease and to control serogroup B outbreaks occurring in institutions or specific regions, as they are likely to save lives and prevent severe sequelae. Incorporation into national programs will require thorough country-specific analysis.

Immunogenicity and safety of the multicomponent meningococcal B vaccine (4CMenB) in children and adolescents: a systematic review and meta-analysis

BACKGROUND

The multicomponent meningococcal serogroup B vaccine (4CMenB) has been licensed in more than 35 countries. However, uncertainties remain about the lowest number of doses required to induce satisfactory, persistent immune responses. We did a systematic review and meta-analysis to provide quantitative estimates for the immunogenicity, persistence of immunogenicity, and safety of 4CMenB vaccine in children and adolescents.

METHODS

For this systematic review and meta-analyses (proportion, head to head, and network), we searched MEDLINE, Scopus, Embase, and ClinicalTrials.gov from database inception to June 30, 2017, for randomised trials that compared the immunogenicity or safety of the 4CMenB vaccine with its originator meningococcal B recombinant vaccine or routine vaccines in children or adolescents. For proportion meta-analyses, we also included single arm trials and follow-up studies of randomised controlled trials. Trials that assessed immunogenicity against at least one of four Neisseria meningitidis serogroup B reference strains (44-76/SL, 5/99, NZ98/254, and M10713) and included participants younger than 18 years who had received two or more doses of the 4CMenB vaccine were eligible for inclusion. We requested individual patient-level data from study authors and extracted data from published reports and online trial registries. We did meta-analyses to assess 4CMenB safety and immunogenicity against the four reference strains 30 days after a primary immunisation course (three doses for children, two doses for adolescents), 30 days after the primary course plus one booster dose (children only), 6 months or more after primary course, and 6 months or more after the booster dose.

FINDINGS

736 non-duplicate records were screened, and ten randomised trials and eight follow-on extension trials on 4CMenB met the inclusion criteria. In intention-to-treat analyses, the overall proportion of children and adolescents who achieved seroconversion 30 days after the primary course of 4CMenB was 92% (95% CI 89-95 [I²=95%, p<0·0001]) for the 44/76-SL strain, 91% (87-95 [I²=95%, p<0·0001]) for the 5/99 strain, 84% (77-90 [I²=97%, p<0·0001]) for the NZ98-254 strain, and 87% (68-99 [I²=97%, p<0·0001]) for the M10713 strain. 6 months after the primary course, the immunogenicity remained adequate to high against all three tested strains (5/99, 44/76-SL, and NZ98/254) in adolescents (≥77%), and against two of four strains (5/99 and 44/76-SL) in children (≥67%): the proportion of patients who achieved seroconversion substantially declined for M10713 (<50%) and NZ98/254 (<35%). A booster dose re-enhanced the proportion of patients who achieved seroconversion (≥93% for all strains). However, immunogenicity remained high 6 months after the booster dose for strains 5/99 (95%) and M10713 (75%) only, whereas the proportion of patients who achieved seroconversion against strains 44/76-SL and NZ98/254 returned to similar proportions recorded 6 months after the primary course (62% for 44/76-SL, 35% for NZ98/254). The incidence of potentially vaccine-related, acute serious adverse events in individuals receiving 4CMenB was low (5·4 per 1000 individuals), but was significantly higher than routine vaccines (1·2 per 1000 individuals).

INTERPRETATION

4CMenB has an acceptable short-term safety profile. The primary course is sufficient to achieve a satisfactory immune response within 30 days of vaccination. A booster dose is required for children to prolong the protection against strain M10713, and the long-term immunogenicity against strain NZ98/254 remains suboptimal.

FUNDING

None.

[Immunisation schedule of the Spanish Association of Paediatrics: 2018 recommendations]

The Advisory Committee on Vaccines of the Spanish Association of Paediatrics annually publishes the immunisation schedule considered optimal for children resident in Spain, according to available evidence on current vaccines. Regarding funded immunisations, 2+1 strategy (2, 4, 11-12 months) with hexavalent (DTPa-IPV-Hib-HB) and 13-valent pneumococcal vaccines are recommended. Administration of the 6-year booster dose with DTPa is recommended, and a poliomyelitis dose for children who had received the 2+1 scheme, as well as Tdap vaccine for adolescents and pregnant women in every pregnancy between 27 and 32 weeks' gestation. The two-dose scheme should be used for MMR (12 months and 2-4 years) and varicella (15 months and 2-4 years). MMRV vaccine could be applied as the second dose if available. Coverage of human papillomavirus vaccination in girls aged 12 with a two dose scheme (0, 6 months) should be improved. Information and recommendation for male adolescents about potential beneficial effects of this immunisation should be provided as well. The new 9 genotypes vaccine is now available, expanding the coverage for both gender. Regarding non-funded immunisations, Committee on Vaccines of the Spanish Association of Paediatrics recommends meningococcal B vaccination, with a 3+1 schedule, and requests to be included in the National Immunisation Program. Tetravalent meningococcal vaccine (MenACWY) is recommended to adolescents (14-18 years) who are going to live in countries with systematic vaccination against ACWY serogroups, and people >6 weeks of age with risk factors or travellers to countries with very high incidence. Vaccination against rotavirus is recommended in all infants.

Antibody persistence and booster responses 24-36 months after different 4CMenB vaccination schedules in infants and children: A randomised trial

OBJECTIVES

This phase IIIb, open-label, multicentre, extension study (NCT01894919) evaluated long-term antibody persistence and booster responses in participants who received a reduced 2 + 1 or licensed 3 + 1 meningococcal serogroup B vaccine (4CMenB)-schedule (infants), or 2-dose catch-up schedule (2-10-year-olds) in parent study NCT01339923.

MATERIALS AND METHODS

Children aged 35 months to 12 years (N = 851) were enrolled. Follow-on participants (N = 646) were randomised 2:1 to vaccination and non-vaccination subsets; vaccination subsets received an additional 4CMenB dose. Newly enrolled vaccine-naïve participants (N = 205) received 2 catch-up doses, 1 month apart (accelerated schedule). Antibody levels were determined using human serum bactericidal assay (hSBA) against MenB indicator strains for fHbp, NadA, PorA and NHBA. Safety was also evaluated.

RESULTS

Antibody levels declined across follow-on groups at 24-36 months versus 1 month post-vaccination. Antibody persistence and booster responses were similar between infants receiving the reduced or licensed 4CMenB-schedule. An additional dose in follow-on participants induced higher hSBA titres than a first dose in vaccine-naïve children. Two catch-up doses in vaccine-naïve participants induced robust antibody responses. No safety concerns were identified.

CONCLUSION

Antibody persistence, booster responses, and safety profiles were similar with either 2 + 1 or 3 + 1 vaccination schedules. The accelerated schedule in vaccine-naïve children induced robust antibody responses.

Emerging clinical experience with vaccines against group B meningococcal disease

The prevention of paediatric bacterial meningitis and septicaemia has recently entered a new era with the availability of two vaccines against capsular group B meningococcus (MenB). Both of these vaccines are based on sub-capsular proteins of the meningococcus, an approach that overcomes the challenges set by the poorly immunogenic MenB polysaccharide capsule but adds complexity to predicting and measuring the impact of their use. This review describes the development and use of MenB vaccines to date, from the use of outer membrane vesicle (OMV) vaccines in MenB outbreaks around the world, to emerging evidence on the effectiveness of the newly available vaccines. While recent data from the United Kingdom supports the potential for protein-based vaccines to provide direct protection against MenB disease in immunised children, further research is required to understand the breadth and duration of this protection. A more detailed understanding of the impact of immunisation with these vaccines on nasopharyngeal carriage of the meningococcus is also required, to inform both their potential to induce herd immunity and to preferentially select for carriage of strains not susceptible to vaccine-induced antibodies. Although a full understanding of the potential impact of these vaccines will only be possible with this additional information, the availability of new tools to prevent the devastating effect of invasive MenB disease is a significant breakthrough in the fight against childhood sepsis and meningitis.

The Therapeutic Benefit of Bacterial Membrane Vesicles

The therapeutic potential of extracellular vesicles from eukaryotes has gained strong interest in recent years. However, research into the therapeutic application of their bacterial counterparts, known as bacterial membrane vesicles, is only just beginning to be appreciated. Membrane vesicles (MVs) from both Gram-positive and Gram-negative bacteria offer significant advantages in therapeutic development, including large-scale, cost effective production and ease of molecular manipulation to display foreign antigens. The nanoparticle size of MVs enables their dissemination through numerous tissue types, and their natural immunogenicity and self-adjuvanting capability can be harnessed to induce both cell-mediated and humoral immunity in vaccine design. Moreover, the ability to target MVs to specific tissues through the display of surface receptors raises their potential use as targeted MV-based anti-cancer therapy. This review discusses recent advances in MV research with particular emphasis on exciting new possibilities for the application of MVs in therapeutic design.