Impact of vaccination on meningococcal epidemiology

Neutrophil extracellular trap-associated protein in cerebrospinal fluid for prognosis evaluation of adult bacterial meningitis: a retrospective case-control study

BACKGROUND AND OBJECTIVES

Central nervous system infections, typified by bacterial meningitis, stand as pivotal emergencies recurrently confronted by neurologists. Timely and precise diagnosis constitutes the cornerstone for efficacious intervention. The present study endeavors to scrutinize the influence of inflammatory protein levels associated with neutrophils in cerebrospinal fluid on the prognosis of central nervous system infectious maladies.

METHODS

This retrospective case series study was undertaken at the Neurology Department of the Second Hospital of Shandong University, encompassing patients diagnosed with infectious encephalitis as confirmed by PCR testing and other diagnostic modalities spanning from January 2018 to January 2024. The quantification of MPO and pertinent inflammatory proteins within patients' cerebrospinal fluid was accomplished through the utilization of ELISA.

RESULTS

We enlisted 25 patients diagnosed with bacterial meningitis, ascertained through PCR testing, and stratified them into two groups: those with favorable prognoses (n = 25) and those with unfavorable prognoses (n = 25). Following assessments for normality and variance, notable disparities in CSF-MPO concentrations emerged between the prognostic categories of bacterial meningitis patients (P < 0.0001). Additionally, scrutiny of demographic data in both favorable and unfavorable prognosis groups unveiled distinctions in CSF-IL-1β, CSF-IL-6, CSF-IL-8, CSF-IL-18, CSF-TNF-α levels, with correlation analyses revealing robust associations with MPO. ROC curve analyses delineated that when CSF-MPO ≥ 16.57 ng/mL, there exists an 83% likelihood of an adverse prognosis for bacterial meningitis. Similarly, when CSF-IL-1β, CSF-IL-6, CSF-IL-8, CSF-IL-18, and CSF-TNF-α levels attain 3.83pg/mL, 123.92pg/mL, 4230.62pg/mL, 35.55pg/mL, and 35.19pg/mL, respectively, there exists an 83% probability of an unfavorable prognosis for bacterial meningitis.

CONCLUSION

The detection of neutrophil extracellular traps MPO and associated inflammatory protein levels in cerebrospinal fluid samples holds promise in prognosticating bacterial meningitis, thereby assuming paramount significance in the prognostic evaluation of patients afflicted with this condition.

Autoimmune/inflammatory syndrome induced by adjuvants (ASIA): past, present, and future implications

Adjuvants, as the name indicates, are adjoined material aimed to assist in functioning as when added to vaccines they are meant to boost the effect and strongly stimulate the immune system. The response of the immune system can be unpredictable, and the autoimmune/inflammatory syndrome induced by adjuvants (ASIA) was developed to address possible adverse reactions of an autoimmune and inflammatory type that may be caused by adjuvants. While ASIA, as a syndrome, was coined and defined in 2011; reports describing patients with vague and nonspecific clinical symptoms following vaccinations appeared much earlier. In other words, ASIA came to define, arrange, and unite the variety of symptoms, related to autoimmunity, caused not by the vaccine itself, rather by the adjuvant part of the vaccine such as aluminum, among others. Accordingly, the introduction of ASIA enabled better understanding, proper diagnosis, and early treatment of the disorder. Furthermore, ASIA was shown to be associated with almost all body systems and various rheumatic and autoimmune diseases such as systemic lupus erythematosus, antiphospholipid syndrome, and systemic sclerosis. In addition, the correlation between COVID-19 and ASIA was noticed during the pandemic. In this review, we summarized the reported effects of adjuvants and medical literature before and after ASIA was defined, the several ways ASIA can manifest and impact different systems of the body, and the incidences of ASIA during the COVID-19 pandemic. It is important to clarify, that vaccines are among, if not the, most effective means of fighting infectious diseases however, we believe that vaccines manufacturing is not above criticism, particularly when it comes to added substances possessing a risk of side effects.

High risk and low prevalence diseases: Adult bacterial meningitis

INTRODUCTION

Acute bacterial meningitis in adults is a rare but serious condition that carries a high rate of morbidity.

OBJECTIVE

This review highlights pearls and pitfalls of acute bacterial meningitis in adults, including presentation, diagnosis, and management in the emergency department (ED) based on current evidence.

DISCUSSION

Meningitis encompasses a broad spectrum of disease involving inflammation of the meninges and subarachnoid space. It classically presents with fever, nuchal rigidity, and altered mental status, but this triad is not present in all cases. Up to 95% of patients will have at least two of the following four cardinal symptoms: fever, nuchal rigidity, altered mental status, and headache. The most common bacterial etiologies are S. pneumoniae and N. meningitidis. Cerebrospinal fluid testing obtained by lumbar puncture remains the gold standard in diagnosis. Head computed tomography prior to lumbar puncture may not be necessary in most patients. Empiric treatment consists of vancomycin, ceftriaxone, and dexamethasone. Elevated intracranial pressure should be managed using established neurocritical care strategies.

CONCLUSION

A better understanding of the pearls and pitfalls of acute bacterial meningitis can assist emergency clinicians in pursuing its timely diagnosis and management.

Invasive Meningococcal Disease and Meningococcal Serogroup B Vaccination in Adults and Their Offspring: Knowledge, Attitudes, and Practices in Italy (2019)

Despite its effectiveness in preventing invasive meningococcal disease (IMD), pediatric uptake of recombinant meningococcal vaccination for serogroup B meningitis (MenB) is low in Italy. This study aimed to investigate knowledge, attitudes, and practice (KAP) about IMD and the vaccine uptake for MenB from July to December 2019, in a sample collected from a series of local Facebook discussion groups from the provinces of Parma and Reggio Emilia (North-Eastern Italy; 337,104 registered users). A self-administered anonymous web-based questionnaire was used to collect demographics, knowledge status, perceived risk for contracting meningitis, attitude towards the utility of meningococcal vaccine, and willingness to receive/perform MenB vaccine in their offspring. In total, 541 parents returned a fully completed questionnaire (response rate of 1.6% of potential recipients), with a mean age of 39.2 years ± 6.3 (78.1% females). Meningococcal infection was identified as severe or highly severe by most participants (88.9%), while it was recognized as being frequent/highly frequent in the general population by 18.6% of respondents. The overall knowledge status was unsatisfactory (57.6% ± 33.6 of correct answers to the knowledge test). Even though 63.4% of participants were somewhat favorable to MenB/MenC vaccines, offspring’s vaccination towards MenB was reported by only 38.7% of participants. In a binary logistic regression model, the male gender of respondents (adjusted odds ratio [aOR] 3.184, 95% confidence interval [95%CI] 1.772 to 5.721), living in a municipality >15,000 inhabitants (aOR 1.675, 95%CI 1.051 to 2.668), reporting a favorable attitude on meningococcus B vaccine (aOR 12.472, 95%CI 3.030 to 51.338), having been vaccinated against serogroup B (aOR 5.624, 95%CI 1.936 to 16.337) and/or serogroup C (aOR 2.652, 95%CI 1.442 to 4.872), and having previously vaccinated their offspring against serogroup C meningococcus (aOR 6.585, 95%CI 3.648 to 11.888) were characterized as positive effectors of offspring’s vaccination. On the contrary, having a higher risk perception on vaccines was identified as the only negative effector (aOR 0.429, 95%CI 0.241 to 0.765). Our results hint towards extensive knowledge gaps on IMD and preventive interventions in the general population, suggesting that a positive attitude towards vaccines and vaccinations could be identified as the main effector also for MenB acceptance. Interventions in the general population aimed at improving confidence, compliance, and acknowledgment of the collective responsibility, as well as preventing actual constraints and the sharing of false beliefs on infectious diseases and their preventive measures, could therefore increase vaccination acceptance in both targeted individuals and their offspring.

Vaccines and Autoimmunity-From Side Effects to ASIA Syndrome

Since vaccines are in fact manufactured chemical compounds such as drugs, the appearance of side effects following their use is not surprising. Similarly, as the main goal of vaccines is to stimulate the immune system bringing out the production of protective antibodies, autoimmune-related side effects as a consequence of increased immune activity do not seem irrational. Fortunately, the rate of such side effects is low; however, the importance of reporting adverse events following vaccinations, understanding the mechanisms behind their appearance, making early diagnosis, and appropriate treatment cannot be overemphasized. In fact, autoimmune-related side effects of vaccines, particularly those based on adjuvants, were reported long before the introduction of the autoimmune/inflammatory syndrome induced by adjuvants (ASIA). Nevertheless, ASIA gathered and united the side effects of vaccines under one title, a step which helped organize the research and call for better immune stimulators than adjuvants. New technologies and methods of making vaccines were clearly noticed during the pandemic of COVID-19 after the introduction of mRNA-based vaccines. In our current paper, we introduce the notion of side effects to vaccines, particularly those of autoimmune nature, the mechanisms of ASIA, and the main vaccines linked with the syndrome including the recent COVID-19 vaccines. The transition from side effects to ASIA is the main idea behind our work.

Epidemiology of invasive meningococcal disease and sequelae in the United Kingdom during the period 2008 to 2017 - a secondary database analysis

Background

Invasive meningococcal disease (IMD) causes high fatality in untreated patients alongside long-term sequelae in 20% survivors. For a comprehensive assessment of epidemiology, an analysis of these sequelae is required. This study aims to investigate the epidemiology of disease between 2008 and 2017 including a description of the sequelae, through the analysis of data collected from the UK Clinical Practice Research Datalink (CPRD) linked with data from the Hospital Episode Statistics (HES), and Office for National Statistics (ONS) mortality registry data.

Methods

This was a 10-year retrospective observational cohort study designed to describe the incidence, case-fatality rate (CFR) and occurrence of sequelae due to meningococcal disease, in the UK between 2007 and 2017 using data from the UK CPRD-HES-ONS. Cases were identified and matched on age, gender, date of diagnosis of IMD and followed-up-time with a control group without IMD. Demographics, clinical characteristics, mortality, and IMD-related sequelae were examined for IMD cases and compared with matched controls for a more comprehensive assessment.

Results

The study analysed 640 IMD patients with majority of the cases diagnosed (76.9%) in a hospital setting. Age-group analysis showed a decrease in the incidence rate of IMD in patients aged <1 year (30.4 – 7.5%) and an increase in those >50 years (10.4 – 27.8%). CFR was slightly higher among females, toddlers, and adults >50 years. No significant change in CFR was observed over study period. Case-control study showed a higher number of IMD sequelae among cases compared to age- and gender-matched controls, especially in those ≥ 50 years.

Conclusion

The study showed that, despite a relatively low incidence rate, IMD is responsible for a high CFR, namely in older age groups and by a high number of IMD sequelae. The study showed that leveraging data from existing databases can be used to complement surveillance data in truly assessing the epidemiology of IMD. Despite the availability of routine vaccination programs, IMD still poses a significant burden in the healthcare system of the UK. Optimization of vaccination programs may be required to reduce the disease burden.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12889-022-12933-3.

Did social distancing measures deployed for SARS-CoV-2/COVID-19 control have an impact on invasive meningococcal disease?

We investigated the impact of social distancing measures, used to contain or mitigate SARS-CoV-2 spread, on the transmission of invasive meningococcal disease (IMD) in Italy. To this end, the temporal correlation between the implementation of lockdown measures in 2020 and IMD incidence was evaluated. A dramatic decline of IMD incidence was observed, suggesting that the measures applied to contain SARS-CoV-2 in Italy affected other infectious diseases transmitted through direct contact and droplets, at least in the early phase of the COVID-19 pandemic.

The Most Influential Papers in Infectious Meningitis Research: A Bibliometric Study

Background

Bibliometric analyses allow detecting citation trends within a field, including assessments of the most cited journals, countries, institutions, topics, types of study, and authors.

Objective

The aim of this study was to perform a bibliometric analysis of the 100 most cited papers within infectious meningitis research.

Materials and Methods

The 100 most cited publications and their data were retrieved from Scopus and Web of Science during 2019.

Results

The New England Journal of Medicine had the greatest number of articles (27) and citations (12,266) in the top 100. Articles were mainly published after the late 1980s. Bacteria were the most discussed agents (72 articles and 26,362 citations), but Cryptococcus sp represented the most-discussed single agent (16 articles and 6,617 citations). Primary research represented 70 articles and 25,754 citations. Among them, the most discussed topic was Clinical Features and Diagnosis/Outcomes (22 articles and 8,325 citations). Among the 27 secondary research articles, the most common type of study was Narrative Review (18 articles and 5,685 citations). The United States was the country with the greatest number of articles (56) and citations (21,388). Centers for Disease Control and Prevention (CDC) and Yale University had the greatest number of articles (six each), being CDC the most cited (3,559).

Conclusions

The most cited articles within meningitis research are primary research studies, more frequently published in high IF journals and by North American institutions. Bacterial meningitis comprises the majority of publications. The articles were mainly published after the AIDS pandemic and after the implementation of the main vaccines for meningitis.

Neuroinfectious Disease Emergencies

Neuroinfectious diseases can affect immunocompetent and immunosuppressed individuals and cause a variety of emergencies including meningitis, encephalitis, and abscess. Neurologic infections are frequently complicated by secondary injuries that also present emergently such as cerebrovascular disease, acute obstructive hydrocephalus, and seizure. In most cases, timely recognition and early treatment of infection can improve the morbidity and mortality of infectious neurologic emergencies.

Systematic literature review of the impact and effectiveness of monovalent meningococcal C conjugated vaccines when used in routine immunization programs

BACKGROUND

Monovalent meningococcal C conjugate vaccine (MCCV) was introduced into the routine immunization program in many countries in Europe and worldwide following the emergence of meningococcal serogroup C (MenC) in the late 1990s. This systematic literature review summarizes the immediate and long-term impact and effectiveness of the different MCCV vaccination schedules and strategies employed.

METHODS

We conducted a systematic literature search for peer-reviewed, scientific publications in the databases of MEDLINE (via PubMed), LILACS, and SCIELO. We included studies from countries where MCCV have been introduced in routine vaccination programs and studies providing the impact and effectiveness of MCCV published between 1st January 2001 and 31st October 2017.

RESULTS

Forty studies were included in the review; 30 studies reporting impact and 17 reporting effectiveness covering 9 countries (UK, Spain, Italy, Canada, Brazil, Australia, Belgium, Germany and the Netherlands). Following MCCV introduction, significant and immediate reduction of MenC incidence was consistently observed in vaccine eligible ages in all countries with high vaccine uptake. The reduction in non-vaccine eligible ages (especially population > 65 years) through herd protection was generally observed 3-4 years following introduction. Vaccine effectiveness (VE) was mostly assessed through screening methods and ranged from 38 to 100%. The VE was generally highest during the first year after vaccination and waned over time. The VE was better maintained in countries employing catch-up campaigns in older children and adolescents, compared to routine infant only schedules.

CONCLUSIONS

MCCV were highly effective, showing a substantial and sustained decrease in MenC invasive meningococcal disease. The epidemiology of meningococcal disease is in constant transition, and some vaccination programs now include adolescents and higher valent vaccines due to the recent increase in cases caused by serogroups not covered by MCCV. Continuous monitoring of meningococcal disease is essential to understand disease evolution in the setting of different vaccination programs.

Culture-Confirmed Invasive Meningococcal Disease in Canada, 2010 to 2014: Characterization of Serogroup B Neisseria meningitidis Strains and Their Predicted Coverage by the 4CMenB Vaccine

Laboratory surveillance of invasive meningococcal disease (IMD) is important to our understanding of the evolving nature of the Neisseria meningitidis strain types causing the disease and the potential coverage of disease strains by the newly developed vaccines. This study examined the molecular epidemiology of culture-confirmed IMD cases in Canada by examining the strain types and the potential coverage of a newly licensed 4CMenB vaccine on Canadian serogroup B N. meningitidis strains. The strain types identified in different parts of Canada appeared to be unique as well as their predicted coverage by the 4CMenB vaccine. These data were compared to data obtained from previous studies done in Canada and elsewhere globally. For effective control of IMD, laboratory surveillance of this type was found to be essential and useful to understand the dynamic nature of this disease.

The molecular epidemiology of culture-confirmed invasive meningococcal disease (IMD) in Canada from 2010 to 2014 was studied with an emphasis on serogroup B Neisseria meningitidis (MenB) isolates, including their predicted coverage by the 4CMenB vaccine. The mean annual incidence rates of culture confirmed IMD varied from 0.19/100,000 in Ontario to 0.50/100,000 in New Brunswick and 0.59/100,000 in Quebec. In both Quebec and Atlantic region, MenB was significantly more common than other serogroups, while in other provinces, both MenB and serogroup Y (MenY) were almost equally common. The majority of MenB cases (67.0%) were in those aged ≤24 years, while most MenC (75.0%) and MenY (69.6%) cases were in adults more than 24 years old. The 349 MenB isolates were grouped into 103 sequence types (STs), 90 of which belonged to 13 clonal complexes (CCs). A large number of 4CMenB antigen genes were found among the Canadian MenB, which is predicted to encode 50 factor H binding protein (fHbp) types, 40 NHBA types, and 55 PorA genotypes. Provinces and regions were found to have their own unique MenB STs. A meningococcal antigen typing system assay predicted an overall MenB coverage by 4CMenB to be 73.6%, with higher coverage predicted for the two most common STs: 100% for ST154 and 95.9% for ST269, leading to higher coverage in both the Atlantic region and Quebec. Higher coverage (81.4%) was also found for MenB recovered from persons aged 15 to 24 years, followed by strains from infants and children ≤4 years old (75.2%) and those aged 5 to 14 years (75.0%).

IMPORTANCE Laboratory surveillance of invasive meningococcal disease (IMD) is important to our understanding of the evolving nature of the Neisseria meningitidis strain types causing the disease and the potential coverage of disease strains by the newly developed vaccines. This study examined the molecular epidemiology of culture-confirmed IMD cases in Canada by examining the strain types and the potential coverage of a newly licensed 4CMenB vaccine on Canadian serogroup B N. meningitidis strains. The strain types identified in different parts of Canada appeared to be unique as well as their predicted coverage by the 4CMenB vaccine. These data were compared to data obtained from previous studies done in Canada and elsewhere globally. For effective control of IMD, laboratory surveillance of this type was found to be essential and useful to understand the dynamic nature of this disease.

Structural basis for recognition and repair of the 3'-phosphate by NExo, a base excision DNA repair nuclease from Neisseria meningitidis

NExo is an enzyme from Neisseria meningitidis that is specialized in the removal of the 3'-phosphate and other 3'-lesions, which are potential blocks for DNA repair. NExo is a highly active DNA 3'-phosphatase, and although it is from the class II AP family it lacks AP endonuclease activity. In contrast, the NExo homologue NApe, lacks 3'-phosphatase activity but is an efficient AP endonuclease. These enzymes act together to protect the meningococcus from DNA damage arising mainly from oxidative stress and spontaneous base loss. In this work, we present crystal structures of the specialized 3'-phosphatase NExo bound to DNA in the presence and absence of a 3'-phosphate lesion. We have outlined the reaction mechanism of NExo, and using point mutations we bring mechanistic insights into the specificity of the 3'-phosphatase activity of NExo. Our data provide further insight into the molecular origins of plasticity in substrate recognition for this class of enzymes. From this we hypothesize that these specialized enzymes lead to enhanced efficiency and accuracy of DNA repair and that this is important for the biological niche occupied by this bacterium.

Do HCWs adequately know about meningitis and 4CMenB vaccine and recommend its use to parents? A cross sectional analysis in Campania Region, Italy

Invasive meningococcal disease (IMD) is a severe disease caused by various Neisseria meningitidis serogroups that represents a serious public health problem worldwide. In Italy, serogroups B and C are the major causes of IMD. On 14 January 2013, the European Medicines Agency authorized the use of the first vaccine available to protect against meningococcal serogroup B (4CMenB). The aim of this study was to assess the IMD epidemiology knowledge and 4CMenB vaccine attitudes of healthcare workers (HCWs) with regard to recommending this vaccine for use, vaccine practices and infectious disease control in the Campania region in Italy. A cross-sectional study was conducted among 293 HCWs (49.5% physicians and 46.4% nurses)interviewed using a self-administered questionnaire. The majority of the HCWs had sufficient knowledge about the disease incidence and lethality, but they were less informed about the higher risk age categories and the serogroups most frequently involved. Additionally, their knowledge about the vaccine was poor with regard to the targeted categories and side effects. Approximately30.0% of the HCWs reported incidences of fever and pain and swelling at the injection site. Moreover,32.8% of the HCWs knew that the risk of developing adverse reactions increases when the 4CMenB vaccine is co-administered with other vaccines. Overall, all of the HCWs were convinced that vaccinations are an important instrument for preventing infectious diseases, and they were aware of their central role in promoting the 4CmenB vaccination and their need to be better informed.

Increase in ST-11 serogroup W Neisseria meningitidis invasive meningococcal disease in Canada, 2016-2018

BACKGROUND

Many countries have experienced increases in invasive meningococcal disease (IMD) due to a serogroup W Neisseria meningitidis (MenW) strain of the multilocus sequence type (ST)-11 clonal complex (CC). MenW ST-11 was first reported in Ontario, Canada, in 2014. By 2016, this strain caused IMD in five provinces and was responsible for 18.8% of the IMD cases in Canada.

OBJECTIVE

To provide an update on invasive MenW disease in Canada including the strain characteristics, specimen source of isolates, age, sex and geographic distribution of cases.

METHODS

N. meningitidis from culture-positive IMD cases are routinely submitted to the National Microbiology Laboratory (NML) for serogroup, serotype, serosubtype and sequence type analysis. The data from January 1, 2016 to December 31, 2018 were analyzed by calculating the proportion of IMD cases caused by MenW compared with other serogroups. In addition, trends based on age, sex and geographic distribution of cases and specimen source of isolates were analyzed based on information on specimen requisition forms.

RESULTS

Over the 3-year period, 292 individual IMD case isolates were analyzed. The percentage of IMD case isolates typed as MenW more than doubled from 19% (n=15) to 44% (n=51) in 2018 when MenW became the most common serogroup, exceeded the number of MenB, MenC or MenY. In total, 93 MenW case isolates were identified, 91% (n=85) belonged to the ST-11 CC. The increase in MenW affected all age groups (but was most common in those older than 60) and both sexes, and occurred across the country but most prevalent in western Canada. The most common specimen source was blood.

CONCLUSION

In 2018, MenW was the most common serogroup for isolates received by the NML from culture-positive IMD cases in Canada. Over 90% of the MenW serogroup isolates belonged to the ST-11 CC. The quadrivalent ACWY meningococcal conjugate vaccine protects against IMD caused by strains in the A, C, W or Y serogroups and therefore may protect against IMD caused by the new MenW ST-11 strain; however, more research is needed. The emergence of variant strains highlight the importance of strain characterization in IMD surveillance and research.

Carriage meningococcal isolates with capsule null locus dominate among high school students in a non-endemic period, Italy, 2012-2013

Meningococcal disease incidence in Italy remains quite low in the overall population except for infants. Within a study on carriage isolates among high school students we aimed to define: i) the prevalence of carriage isolates, ii) the phenotypic and iii) the molecular features of meningococci by Whole Genome Sequencing (WGS). A total of 1697 pharyngeal samples from undergraduate students (age range 14-19 years) were collected from 2012 to 2013 from six larger cities in Italy. One hundred and twenty culture positive meningococci (7%) were analyzed. Carriage isolates were sent to the National Reference Laboratory for invasive meningococcal disease (IMD) for PCR-based serogroup identification, Multilocus Sequence Typing, PorA and FetA typing. Moreover, factor H binding protein (fHbp), Neisseria Heparin Binding Antigen (NHBA) and Neisserial adhesin A (NadA) were typed. Core genome MLST (cgMLST) was performed on a subsample of 75 carriage isolates. Capsule null locus (cnl) predominated (47%), followed by serogroup B (27%). The antimicrobial susceptibility profile revealed an high prevalence of reduced susceptibility to penicillin G (54%) and a full susceptibility to ceftriaxone, ciprofloxacin and rifampicin. Carriage isolates presented a high genetic diversity: the clonal complexes (cc_s) cc1136, cc198 and cc41/44, were the predominant. An high heterogeneity was also observed for PorA and FetA types. The fhbp and nhba genes were identified in all the carriage isolates; only 5% of the carriage isolates presented the nadA gene. The core genome MLST analysis revealed that the majority of the cnl isolates clustered in a distinct group. The evidence gathered during this study provides the estimate of carriage isolates in high school students in a non-epidemic period in Italy that was lower than expected. Moreover, the highest proportion of carriage isolates were cnl and, overall, they were molecular heterogeneous.

Safety and immunogenicity of a pentavalent meningococcal conjugate vaccine containing serogroups A, C, Y, W, and X in healthy adults: a phase 1, single-centre, double-blind, randomised, controlled study

BACKGROUND

Invasive meningococcal disease is an important public health problem, especially in sub-Saharan Africa. After introduction of MenAfriVac in 2010, Neisseria meningitidis serogroup A disease has been almost eliminated from the region. However, serogroups C, W, Y, and X continue to cause disease outbreaks. We assessed the NmCV-5 pentavalent meningococcal conjugate vaccine targeting A, C, Y, W, and X serogroups in a first-in-man, phase 1 study.

METHODS

We did a single-centre, double-blind, randomised controlled trial at a research clinic in Baltimore (MD, USA). Participants were healthy adults aged 18-45 years with no history of meningococcal vaccination or previous meningococcal infection. We randomly assigned participants (1:1:1) by an SAS-generated random schedule to a single, 0·5 mL, intramuscular injection of aluminium-phosphate adjuvanted NmCV-5, non-adjuvanted NmCV-5, or control (the quadrivalent meningococcal conjugate vaccine Menactra). The randomisation sequence used a permuted block design with randomly chosen block sizes of three and six. The vaccines were prepared, labelled, and administered with procedures to ensure participants and study personnel remained masked to treatment. After vaccination, participants were observed in the clinic for 60 min for adverse reactions. Participants recorded daily temperature and injection site or systemic reactions at home and returned to the clinic for follow-up visits on days 7, 28, and 84 for safety assessments; blood samples were also collected on day 7 for safety laboratory assessment. A phone call contact was made 6 months after vaccination. Serum was collected before vaccination and 28 days after vaccination for immunological assessment with a rabbit complement-dependent serum bactericidal antibody (rSBA) assay. The primary objective was an intention-to-treat assessment of safety, measuring local and systemic reactogenicity over 7 days, unsolicited adverse events through 28 days, and serious adverse events over 6 months. The secondary objective for the assessment of immunogenicity, was a per-protocol analysis of rSBA before and 28 days after vaccination. This trial is registered with ClinicalTrials.gov, number NCT02810340.

FINDINGS

Between Aug 17, 2016, and Feb 16, 2017, we assigned 20 participants to each vaccine. All vaccines were well-tolerated. Pain was the most common local reaction, occurring in 12 (60%), ten (50%), and seven (35%) participants in the adjuvanted NmCV-5, non-adjuvanted NmCV-5, and control groups, respectively. Headache was the most common systemic reaction, occurring in five (25%), three (15%), and three (15%), respectively. Most solicited reactogenicity adverse reactions were mild (60 [74%] of 81) and all were self-limiting. None of the differences in proportions of individuals with each solicited reaction was significant (p>0·300 for all comparisons) between the three vaccination groups. There were no serious adverse events and 19 unsolicited non-serious adverse events in 14 (23%) participants. Both adjuvanted and non-adjuvanted NmCV-5 elicited high rSBA titres against all five meningococcal serogroups. The pre-vaccination geometric mean titres (GMTs) ranged from 3·36 to 53·80 for the control, from 6·28 to 187·00 for the adjuvanted vaccine, and from 4·29 to 350·00 for the non-adjuvanted vaccine, and the post-vaccination GMT ranged from 3·14 to 3214 for the control, from 1351 to 8192 for the adjuvanted vaccine, and from 1607 to 11 191 for the non-adjuvanted vaccine. Predicted seroprotective responses (ie, an increase in rSBA titres of eight times or more) for the adjuvanted and non-adjuvanted NmCV-5 were similar to control responses for all five serogroups.

INTERPRETATION

The adjuvanted and non-adjuvanted NmCV-5 vaccines were well tolerated and did not produce concerning adverse effects and resulted in immune responses that are predicted to confer protection against all five targeted serogroups of invasive meningococcal disease. Further clinical testing of NmCV-5 is ongoing, and additional clinical trials are necessary to confirm the safety and immunogenicity of NmCV-5 in target populations.

FUNDING

UK Department for International Development.

Discordant Effects of Licensed Meningococcal Serogroup B Vaccination on Invasive Disease and Nasal Colonization in a Humanized Mouse Model

Background

The multicomponent meningococcal serogroup B vaccine (4CMenB) is an outer membrane vesicle and recombinant protein-based vaccine licensed to protect against serogroup B meningococcal disease. It remains unknown whether this vaccine will prevent carriage or transmission, key aspects in long-term vaccine success and disease eradication.

Methods

Using a "humanized" transgenic mouse model of nasal colonization, we took a systematic approach to estimate the potential for carriage prevention against antigenically diverse Neisseria meningitidis strains and to compare this protection to an invasive meningococcal disease challenge model.

Results

The 4CMenB vaccine prevented morbidity and mortality after lethal invasive doses of all meningococcal strains tested. Immunization effectively prevented carriage with only 1 of 4 single antigen-matched strains but reduced or prevented nasal colonization by all 4 isolates with multiple cross-reacting antigens. Each immunized mouse had substantial immunoglobulin G targeting the challenge strains, indicating that antibody correlates with protection against sepsis but not nasal carriage.

Conclusions

Immunization with the 4CMenB vaccine elicits a robust humoral response that correlates with protection against invasive challenge but not with prevention of asymptomatic colonization. This suggests that widespread use of this vaccine will reduce morbidity and mortality rates in immunized individuals, with the potential to contribute to herd protection against a subset of strains.

The Global Meningococcal Initiative: global epidemiology, the impact of vaccines on meningococcal disease and the importance of herd protection

INTRODUCTION

The 2015 Global Meningococcal Initiative (GMI) meeting discussed the global importance of meningococcal disease (MD) and its continually changing epidemiology. Areas covered: Although recent vaccination programs have been successful in reducing incidence in many countries (e.g. Neisseria meningitidis serogroup [Men]C in Brazil, MenA in the African meningitis belt), new clones have emerged, causing outbreaks (e.g. MenW in South America, MenC in Nigeria and Niger). The importance of herd protection was highlighted, emphasizing the need for high vaccination uptake among those with the highest carriage rates, as was the need for boosters to maintain individual and herd protection following decline of immune response after primary immunization. Expert commentary: The GMI Global Recommendations for Meningococcal Disease were updated to include a recommendation to enable access to whole-genome sequencing as for surveillance, guidance on strain typing to guide use of subcapsular vaccines, and recognition of the importance of advocacy and awareness campaigns.