Meningococcal B Vaccination (4CMenB) in Infants and Toddlers

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.

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.

YraP Contributes to Cell Envelope Integrity and Virulence of Salmonella enterica Serovar Typhimurium

Mutations in σ^E-regulated lipoproteins have previously been shown to impact bacterial viability under conditions of stress and during in vivo infection. YraP is conserved across a number of Gram-negative pathogens, including Neisseria meningitidis, where the homolog is a component of the Bexsero meningococcal group B vaccine. Investigations using laboratory-adapted Escherichia coli K-12 have shown that yraP mutants have elevated sensitivity to a range of compounds, including detergents and normally ineffective antibiotics. In this study, we investigate the role of the outer membrane lipoprotein YraP in the pathogenesis of Salmonella enterica serovar Typhimurium. We show that mutations in S Typhimurium yraP result in a defective outer membrane barrier with elevated sensitivity to a range of compounds. This defect is associated with attenuated virulence in an oral infection model and during the early stages of systemic infection. We show that this attenuation is not a result of defects in lipopolysaccharide and O-antigen synthesis, changes in outer membrane protein levels, or the ability to adhere to and invade eukaryotic cell lines in vitro.

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.

Strategies to develop vaccines of pediatric interest

INTRODUCTION

The success of the vaccines available on the market has significantly increased interest in vaccine development. Areas covered: The main aim of this paper is to discuss the most important vaccines of pediatric interest that are currently being developed. New pneumococcal vaccines and vaccines against group B Streptococcus, Staphylococcus aureus and respiratory syncytial virus are analyzed in detail. Expert commentary: Advances in understanding human immunology, including human monoclonal antibody identification, sequencing technology, and the ability to solve atomic level structures of vaccine targets have provided tools to guide the rational design of future vaccines. It is likely that some of these vaccines will reach the market in the future and will thus partially contribute to the prevention of very severe diseases that significantly affect the morbidity and mortality of children. However, further studies in animals and several clinical trials in children must be performed before new vaccines become licensed.