Effectiveness of Meningococcal Vaccines at Reducing Invasive Meningococcal Disease and Pharyngeal Neisseria meningitidis Carriage: A Systematic Review and Meta-analysis.

BACKGROUND: Invasive meningococcal disease (IMD), caused by Neisseria meningitidis, leads to significant morbidity and mortality worldwide. This review aimed to establish the effectiveness of meningococcal vaccines at preventing IMD and N. meningitidis pharyngeal carriage. METHODS: A search within PubMed, Embase, Scopus, and unpublished studies up to 1 February 2020 was conducted. RESULTS: After removal of duplicates, 8565 studies were screened and 27 studies included. Protection was provided by meningococcal C vaccines for group C IMD (odds ratio [OR], 0.13 [95% confidence interval {CI}, .07-.23]), outer membrane vesicle (OMV) vaccines against group B IMD (OR, 0.35 [95% CI, .25-.48]), and meningococcal A, C, W, Y (MenACWY) vaccines against group ACWY IMD (OR, 0.31 [95% CI, .20-.49]). A single time series analysis found a reduction following an infant 4CMenB program (incidence rate ratio, 0.25 [95% CI, .19-.36]). Multivalent MenACWY vaccines did not reduce carriage (relative risk [RR], 0.88 [95% CI, .66-1.18]), unlike monovalent C vaccines (RR, 0.50 [95% CI, .26-.97]). 4CMenB vaccine had no effect on group B carriage (RR, 1.12 [95% CI, .90-1.40]). There was also no reduction in group B carriage following MenB-FHbp vaccination (RR, 0.98 [95% CI, .53-1.79]). CONCLUSIONS: Meningococcal conjugate C, ACWY, and OMV vaccines are effective at reducing IMD. A small number of studies demonstrate that monovalent C conjugate vaccines reduce pharyngeal N. meningitidis carriage. There is no evidence of carriage reduction for multivalent MenACWY, OMV, or recombinant MenB vaccines, which has implications for immunization strategies. CLINICAL TRIALS REGISTRATION: CRD42018082085 (PROSPERO).

Invasive Meningococcal Disease, 2011-2020, and Impact of the COVID-19 Pandemic, England.

Invasive meningococcal disease incidence in England declined from 1.93/100,000 persons (1,016 cases) in 2010-11 to 0.95/100,000 (530 cases) in 2018-19 and 0.74/100,000 in 2019-20 (419 cases). During national lockdown for the coronavirus disease pandemic (April-August 2020), incidence was 75% lower than during April-August 2019.

Meningococcal carriage in Norwegian teenagers: strain characterisation and assessment of risk factors.

Teenagers have a higher risk of invasive meningococcal disease (IMD) than the general population. This cross-sectional study aimed to characterise strains of Neisseria meningitidis circulating among Norwegian teenagers and to assess risk factors for meningococcal carriage. Oropharyngeal swabs were collected from secondary-school students in southeastern Norway in 2018-2019. Meningococcal isolates were characterised using whole genome sequencing. Risk factors for meningococcal carriage were assessed from questionnaire data. Samples were obtained from 2296 12-24-year-olds (majority 13-19-year-olds). N. meningitidis was identified in 167 (7.3%) individuals. The highest carriage rate was found among 18-year-olds (16.4%). Most carriage isolates were capsule null (40.1%) or genogroup Y (33.5%). Clonal complexes cc23 (35.9%) and cc198 (32.3%) dominated and 38.9% of carriage strains were similar to invasive strains currently causing IMD in Norway. Use of Swedish snus (smokeless tobacco) (OR 1.56, 95% CI 1.07-2.27), kissing >two persons/month (OR 2.76, 95% CI 1.49-5.10) and partying >10 times/3months (OR 3.50, 95% CI 1.45-8.48) were associated with carriage, while age, cigarette smoking, sharing of drinking bottles and meningococcal vaccination were not. The high meningococcal carriage rate among 18-year-olds is probably due to risk-related behaviour. Use of Swedish snus is possibly a new risk factor for meningococcal carriage. Almost 40% of circulating carriage strains have invasive potential.

Eliminating Meningococcal Epidemics From the African Meningitis Belt: The Case for Advanced Prevention and Control Using Next-Generation Meningococcal Conjugate Vaccines.

The introduction and rollout of a meningococcal serogroup A conjugate vaccine, MenAfriVac, in the African meningitis belt has eliminated serogroup A meningococcal infections for >300 million Africans. However, serogroup C, W, and X meningococci continue to circulate and have been responsible for focal epidemics in meningitis belt countries. Affordable multivalent meningococcal conjugate vaccines are being developed to prevent these non-A epidemics. This article describes the current epidemiologic situation and status of vaccine development and highlights questions to be addressed to most efficiently use these new vaccines.

University-Based Outbreaks of Meningococcal Disease Caused by Serogroup B, United States, 2013-2018.

We reviewed university-based outbreaks of meningococcal disease caused by serogroup B and vaccination responses in the United States in the years following serogroup B meningococcal (MenB) vaccine availability. Ten university-based outbreaks occurred in 7 states during 2013-2018, causing a total of 39 cases and 2 deaths. Outbreaks occurred at universities with 3,600-35,000 undergraduates. Outbreak case counts ranged from 2 to 9 cases; outbreak duration ranged from 0 to 376 days. All 10 universities implemented MenB vaccination: 3 primarily used MenB-FHbp and 7 used MenB-4C. Estimated first-dose vaccination coverage ranged from 14% to 98%. In 5 outbreaks, additional cases occurred 6-259 days following MenB vaccination initiation. Although it is difficult to predict outbreak trajectories and evaluate the effects of public health response measures, achieving high MenB vaccination coverage is crucial to help protect at-risk persons during outbreaks of meningococcal disease caused by this serogroup.

Comparison of Immune Responses to Two Quadrivalent Meningococcal Conjugate Vaccines (CRM197 and Diphtheria Toxoid) in Healthy Adults.

BACKGROUND: After the introduction of the meningococcal ACWY-CRM197 conjugate vaccine (MenACWY-CRM) in 2012 and the meningococcal ACWY-diphtheria toxoid conjugate vaccine (MenACWY-DT) in 2014, immunization was recommended for certain high-risk groups including new military recruits in Korea. However, comparative immunogenicity studies for these vaccines have not been performed in Korea. Here, we compared the immunogenicity of these two vaccines in healthy adults. METHODS: A total of 64 adults, 20-49 years of age, were randomly divided into two groups (1:1) to receive either of the two vaccines. The sera were obtained before and 1 month after vaccination and tested for serogroup-specific serum bactericidal activity using baby rabbit complement. RESULTS: There were no significant differences post-vaccination in the geometric mean indices and the seropositive rate to all serogroups between the vaccines. The proportion of seropositive subjects after vaccination ranged from 88% to 100%. CONCLUSION: Both meningococcal conjugate vaccines showed good immunogenicity in healthy Korean adults without statistically significant differences. Further investigations for serotype distribution of circulating meningococci and the immune interference between other diphtheria toxin-containing vaccines concomitantly used for military recruits are needed to optimize immunization policies. TRIAL REGISTRATION: Clinical Research Information Service Identifier: KCT0002460.

Genomic Surveillance of 4CMenB Vaccine Antigenic Variants among Disease-Causing Neisseria meningitidis Isolates, United Kingdom, 2010-2016.

In September 2015, 4CMenB meningococcal vaccine was introduced into the United Kingdom infant immunization program without phase 3 trial information. Understanding the effect of this program requires enhanced surveillance of invasive meningococcal disease (IMD) Neisseria meningitidis isolates and comparison with prevaccination isolates. Bexsero Antigen Sequence Types (BASTs) were used to analyze whole-genome sequences of 3,073 prevaccine IMD N. meningitidis isolates obtained during 2010-2016. Isolates exhibited 803 BASTs among 31 clonal complexes. Frequencies of antigen peptide variants were factor H binding protein 1, 13.4%; Neisserial heparin-binding antigen 2, 13.8%; Neisseria adhesin A 8, 0.8%; and Porin A-VR2:P1.4,10.9%. In 2015-16, serogroup B isolates showed the highest proportion (35.7%) of exact matches to >1 Bexsero components. Serogroup W isolates showed the highest proportion (93.9%) of putatively cross-reactive variants of Bexsero antigens. Results highlighted the likely role of cross-reactive antigens. BAST surveillance of meningococcal whole-genome sequence data is rapid, scalable, and portable and enables international comparisons of isolates.

Emergency Meningococcal ACWY Vaccination Program for Teenagers to Control Group W Meningococcal Disease, England, 2015-2016.

During the first 12 months of an emergency meningococcal ACWY vaccination program for teenagers in England, coverage among persons who left school in 2015, the first cohort to be vaccinated, was 36.6%. There were 69% fewer group W meningococcal cases than predicted by trend analysis and no cases in vaccinated teenagers.

Serogroup B Meningococcal Disease Vaccine Recommendations at a University, New Jersey, USA, 2016.

In response to a university-based serogroup B meningococcal disease outbreak, the serogroup B meningococcal vaccine Trumenba was recommended for students, a rare instance in which a specific vaccine brand was recommended. This outbreak highlights the challenges of using molecular and immunologic data to inform real-time response.

Impact and effectiveness of meningococcal vaccines: a review.

OBJECTIVES: To summarize and critically evaluate the evidence on the impact and effectiveness of meningococcal vaccination programs around the world in order to inform decisionmaking in Latin America and the Caribbean. METHODS: A review of the literature was conducted following several components of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. PubMed Central® was searched for papers published in any language from January 1999 - March 2017. RESULTS: In all, 32 studies were included, most of which evaluated the meningococcal C conjugate vaccine. Fourteen studies measured effectiveness and 30 measured impact. The effectiveness of polysaccharide vaccines was 65% - 83.7% (different age groups), while the effectiveness of the conjugate vaccines was 66% - 100%. Incidence decline of laboratory-confirmed meningococcal disease for the conjugate vaccine ranged from 77% - 100% among different ages groups. The only study that evaluated the protein subunit vaccine reported a vaccine effectiveness of 82.9%. CONCLUSIONS: The studies reviewed show impact and effectiveness of both polysaccharide vaccines and conjugate vaccines on vaccine-serogroup meningococcal disease. The conjugate vaccines, however, show higher impact and effectiveness with longer-lasting protection over the polysaccharide vaccines. Given the variance in potential use of a meningococcal vaccine, epidemiological surveillance systems should be strengthened to inform national decisions.

Population-Level Persistence of Immunity 2 Years After the PsA-TT Mass-Vaccination Campaign in Mali.

BACKGROUND: In 2010, Africa's first preventive meningococcal mass vaccination campaign was launched using a newly developed Neisseria meningitidis group A (NmA) polysaccharide-tetanus toxoid conjugate vaccine, PsA-TT (MenAfriVac), designed specifically for the meningitis belt. Given PsA-TT's recent introduction, the duration of protection against meningococcal group A is unknown. METHODS: We conducted a household-based, age-stratified seroprevalence survey in Bamako, Mali, in 2012, 2 years after the vaccination campaign targeted all 1- to 29-year-olds. Randomly selected participants who had been eligible for PsA-TT provided a blood sample and responded to a questionnaire. Sera were analyzed to assess NmA-specific serum bactericidal antibody titers using rabbit complement (rSBA) and NmA-specific immunoglobulin G (IgG) by enzyme-linked immunosorbent assay. The proportion of participants putatively protected and the age group- and sex-specific rSBA geometric mean titers (GMTs) and IgG geometric mean concentrations (GMCs) were determined. RESULTS: Two years postvaccination, nearly all of the 800 participants (99.0%; 95% confidence interval [CI], 98.3%-99.7%) maintained NmA-specific rSBA titers ≥8, the accepted threshold for protection; 98.6% (95% CI, 97.8%-99.4%) had titers ≥128, and 89.5% (95% CI, 87.4%-91.6%) had titers ≥1024. The rSBA GMTs were significantly higher in females than in males aged <18 years at vaccination (P < .0001). NmA-specific IgG levels ≥2 µg/mL were found in 88.5% (95% CI, 86.3%-90.7%) of participants. CONCLUSIONS: Two years after PsA-TT introduction, a very high proportion of the population targeted for vaccination maintains high antibody titers against NmA. Assessing the duration of protection provided by PsA-TT is a priority for implementing evidence-based vaccination strategies. Representative, population-based seroprevalence studies complement clinical trials and provide this key evidence.

Higher Tetanus Toxoid Immunity 2 Years After PsA-TT Introduction in Mali.

BACKGROUND: In 2010, mass vaccination with a then-new meningococcal A polysaccharide-tetanus toxoid protein conjugate vaccine (PsA-TT, or MenAfriVac) was undertaken in 1- to 29-year-olds in Bamako, Mali. Whether vaccination with PsA-TT effectively boosts tetanus immunity in a population with heterogeneous baseline tetanus immunity is not known. We assessed the impact of PsA-TT on tetanus toxoid (TT) immunity by quantifying age- and sex-specific immunity prior to and 2 years after introduction. METHODS: Using a household-based, age-stratified design, we randomly selected participants for a prevaccination serological survey in 2010 and a postvaccination survey in 2012. TT immunoglobulin G (IgG) antibodies were quantified and geometric mean concentrations (GMCs) pre- and postvaccination among all age groups targeted for vaccination were compared. The probability of TT IgG levels ≥0.1 IU/mL (indicating short-term protection) and ≥1.0 IU/mL (indicating long-term protection) by age and sex was determined using logistic regression models. RESULTS: Analysis of 793 prevaccination and 800 postvaccination sera indicated that while GMCs were low pre-PsA-TT, significantly higher GMCs in all age-sex strata were observed 2 years after PsA-TT introduction. The percentage with short-term immunity increased from 57.1% to 88.4% (31.3-point increase; 95% confidence interval [CI], 26.6-36.0;, P < .0001) and with long-term immunity increased from 20.0% to 58.5% (38.5-point increase; 95% CI, 33.7-43.3; P < .0001) pre- and postvaccination. CONCLUSIONS: Significantly higher TT immunity was observed among vaccine-targeted age groups up to 2 years after Mali's PsA-TT mass vaccination campaign. Our results, combined with evidence from clinical trials, strongly suggest that conjugate vaccines containing TT such as PsA-TT should be considered bivalent vaccines because of their ability to boost tetanus immunity.

Carriage rate and effects of vaccination after outbreaks of serogroup C meningococcal disease, Brazil, 2010.

During 2010, outbreaks of serogroup C meningococcal (MenC) disease occurred in 2 oil refineries in São Paulo State, Brazil, leading to mass vaccination of employees at 1 refinery with a meningococcal polysaccharide A/C vaccine. A cross-sectional study was conducted to assess the prevalence of meningococci carriage among workers at both refineries and to investigate the effect of vaccination on and the risk factors for pharyngeal carriage of meningococci. Among the vaccinated and nonvaccinated workers, rates of overall meningococci carriage (21.4% and 21.6%, respectively) and of MenC carriage (6.3% and 4.9%, respectively) were similar. However, a MenC strain belonging to the sequence type103 complex predominated and was responsible for the increased incidence of meningococcal disease in Brazil. A low education level was associated with higher risk of meningococci carriage. Polysaccharide vaccination did not affect carriage or interrupt transmission of the epidemic strain. These findings will help inform future vaccination strategies.

The important lessons lurking in the history of meningococcal epidemiology.

INTRODUCTION: The epidemiology of invasive meningococcal disease (IMD), a rare but potentially fatal illness, is typically described as unpredictable and subject to sporadic outbreaks. AREAS COVERED: Meningococcal epidemiology and vaccine use during the last ~ 200 years are examined within the context of meningococcal characterization and classification to guide future IMD prevention efforts. EXPERT OPINION: Historical and contemporary data highlight the dynamic nature of meningococcal epidemiology, with continued emergence of hyperinvasive clones and affected regions. Recent shifts include global increases in serogroup W disease, meningococcal antimicrobial resistance (AMR), and meningococcal urethritis; additionally, unvaccinated populations have experienced disease resurgences following lifting of COVID-19 restrictions. Despite these changes, a close analysis of meningococcal epidemiology indicates consistent dominance of serogroups A, B, C, W, and Y and elevated IMD rates among infants and young children, adolescents/young adults, and older adults. Demonstrably effective vaccines against all 5 major disease-causing serogroups are available, and their prophylactic use represents a powerful weapon against IMD, including AMR. The World Health Organization's goal of defeating meningitis by the year 2030 demands broad protection against IMD, which in turn indicates an urgent need to expand meningococcal vaccination programs across major disease-causing serogroups and age-related risk groups.

Exploring meningococcal serogroup B vaccination conversations under shared clinical decision-making in the US.

OBJECTIVE: In 2019, the United States Advisory Committee on Immunization Practices (ACIP) updated their meningococcal serogroup B (MenB) vaccination recommendation for 16-|23-year-olds from individual to shared clinical decision-making (SCDM). SCDM recommendations are individually based and informed by a decision process between patients and healthcare providers (HCPs). MenB vaccination among 16-23-year-olds remains low. We examined recorded conversations in which MenB vaccine-related discussions between HCPs and patients/caregivers took place, and how these interactions changed following the updated SCDM recommendation. METHODS: An analysis of recordings where MenB vaccination was discussed between HCPs and patients (16-|23 years old)/caregivers was conducted using retrospective anonymized dialogue data (January 2015-October 2022). Shared decision-making strength was measured using a modified OPTION5 framework. RESULTS: Of 97 included recorded conversations, the average duration was 11.3 min. Within these conversations, MenB disease was discussed for 0.25 min (38.9% of words in total vaccine-preventable diseases discussion) and MenB vaccination was discussed for 1.36 min (60.9% of words in total vaccine discussion), on average. HCPs spoke 78.8% of MenB vaccine-related words and most (99.0%) initiated the MenB vaccination discussion. In 40.2% of recordings, HCPs acknowledged the MenB vaccine without providing a clear recommendation. HCP recommendations often favored MenB vaccination (87.0%) and recommendations were 21.4% stronger post-recommendation change to SCDM. As measured by the modified OPTION5 framework, most recordings did not reflect a high degree of shared decision-making between HCPs and patients/caregivers. CONCLUSIONS: MenB vaccination discussions were brief, and the degree of shared decision-making was low. Targeted education of HCPs and patients/caregivers may improve MenB vaccination awareness, SCDM implementation, and vaccine uptake.

Meningitis is a serious and sometimes deadly disease. In the United States (US), the Centers for Disease Control and Prevention (CDC) recommends that 16­23-year-olds get vaccinated against meningococcal serogroup B (MenB), which causes a specific type of meningitis called invasive meningococcal disease. As of 2019, the CDC recommends that healthcare providers and patients or their caregivers have a shared decision-making discussion about deciding to get vaccinated against MenB. Despite these recommendations, vaccination against MenB among 16­23-year-olds is very low. Only about 3 in 10 17-year-olds had received the MenB vaccine in 2022. We studied conversations between healthcare providers and patients or their caregivers that included discussions of MenB vaccination. These discussions were largely brief and led by the healthcare providers. We found that healthcare providers most often made recommendations that were in favor of their patients getting vaccinated against MenB. However, we also found that healthcare providers missed many opportunities to have these shared decision-making discussions about MenB vaccination with patients or their caregivers. Providing education and resources for patients, caregivers, and healthcare providers focused on increasing awareness about MenB vaccination and the role they can play in having shared decision-making discussions may lead to more adolescents and young adults getting vaccinated against MenB. More research is needed to find out how we can improve MenB vaccination coverage in the US.

Cost-effectiveness analysis of vaccination strategies against meningococcal disease for children under nine years of age in China.

Meningococcal vaccination strategies in China are intricate, including multiple vaccines targeting different serogroups. The current National Immunization Program (NIP) includes two polysaccharide vaccines for serogroups A and C (MPV-A and MPV-AC), covering limited serogroups and requiring adaptation. This study aims to evaluate the cost-effectiveness of replacing the current strategy with alternative strategies utilizing non-NIP vaccines to inform policy decisions. From a societal perspective, a decision tree-Markov model was constructed to simulate the economic and health consequences of meningococcal disease in a 2019 birth cohort with four vaccination strategies. Epidemiology, vaccine efficacy, cost, and other parameters were derived from previous studies. We conducted sensitivity analyses to assess the robustness of the findings and explored prices for non-NIP vaccines that enable cost-effective strategies. Compared to the current strategy, alternative strategies using quadrivalent polysaccharide vaccine (MPV-4), bivalent conjugate vaccine (MCV-AC), and quadrivalent conjugate vaccine (MCV-4) could avoid 91, 286, and 455 more meningococcal cases. The ICERs were estimated at approximately $250 thousand/QALY, $450 thousand/QALY, and $1.5 million/QALY, all exceeding the threshold of three times GDP per capita. The alternative strategies were not cost-effective. However, if vaccine prices were reduced to $3.9 for MPV-4, $9.9 for MCV-AC, and $12 for MCV-4, the corresponding strategy would be cost-effective. The current meningococcal vaccination strategy in China could effectively prevent the disease at a low cost, but with limited serogroup coverage. Strategies using MPV-4, MCV-AC, or MCV-4 could increase health benefits at a substantial cost, and might become cost-effective if vaccine prices decrease.

United States Physicians' Knowledge, Attitudes, and Practices Regarding Meningococcal Vaccination for Healthy Adolescents and Young Adults.

PURPOSE: The United States Advisory Committee on Immunization Practices (ACIP) recommends vaccination against meningococcal serogroups A, C, W, and Y (MenACWY) for all 11-12-year-olds, with a booster dose for 16-year-olds, and against meningococcal serogroup B (MenB) for 16-23-year-olds under shared clinical decision-making (SCDM). However, uptake of the MenB vaccine and the MenACWY booster dose is low. This study investigated United States physicians' knowledge, attitudes, and practices regarding recommending MenB and MenACWY vaccines to non-high-risk older adolescents and young adults. METHODS: An online survey was conducted in April-May 2022 among pediatricians, family physicians (FPs), general practitioners (GPs), and internists who had recommended the MenB and/or the MenACWY vaccine(s) to at least one 16-23-year-old in the past year. RESULTS: Among 407 participants, 50% correctly identified MenB as the leading cause of meningococcal disease among adolescents and young adults. Furthermore, 46% of physicians (47% of pediatricians, 40% of FPs and GPs, 53% of internists) answered correctly that MenB vaccination is recommended under SCDM, and 82% of physicians (96% of pediatricians, 70% of FPs and GPs, 65% of internists) answered correctly that MenACWY vaccination is routinely recommended. Among MenB-vaccinators, 78% reported having received some training or other information on implementing SCDM, and 65% rated recommending MenB vaccination as very important. DISCUSSION: Knowledge gaps, which varied by specialty, were identified regarding meningococcal disease and vaccine recommendations, particularly regarding MenB. Targeted education of physicians may facilitate discussions about MenB vaccination.

Analyzing the dynamics of meningococcal vaccinations initiatives by local government units in Poland (2017-2021) - Scope, challenges and recommendations.

INTRODUCTION: Meningococcal vaccinations are recommended by Polish public health authorities but lack coverage under health insurance, prompting Local Government Units (LGUs) to implement local health policy programs. This study examines the effectiveness and impact of LGU-driven meningococcal vaccination initiatives in Poland between 2017 and 2021. MATERIAL AND METHODS: A retrospective analysis utilized data from reports on local public health interventions submitted annually to the Ministry of Health in Poland. The study focused on the number of meningococcal vaccination programs, their scope, the vaccinated population, and associated program costs. Additionally, nationwide data on meningococcal disease incidence and vaccine uptake were analyzed. RESULTS: Within LGUs programs, 48,617 individuals received meningococcal vaccinations, constituting approximately 10% of all vaccinations in Poland during the study period. Notably, cities with poviat rights spearheaded programs covering 54% of the total participants. The total cost incurred by these initiatives amounted to EUR 2,553,661. CONCLUSIONS: While LGUs activities positively contributed to increased meningococcal vaccination rates, the overall engagement of local governments remains limited. The findings underscore the importance of expanding local government involvement in meningococcal vaccination programs to address public health needs effectively. Improved collaboration and increased funding may enhance the reach and impact of these initiatives.

Invasive meningococcal disease in South-Eastern European countries: Do we need to revise vaccination strategies?

Invasive meningococcal disease (IMD) is an acute life-threatening infection caused by the gram-negative bacterium, Neisseria meningitidis. Globally, there are approximately half a million cases of IMD each year, with incidence varying across geographical regions. Vaccination has proven to be successful against IMD, as part of controlling outbreaks, and when incorporated into national immunization programs. The South-Eastern Europe Meningococcal Advocacy Group (including representatives from Croatia, the Czech Republic, Greece, Hungary, Poland, Romania, Serbia, Slovenia and Ukraine) was formed in order to discuss the potential challenges of IMD faced in the region. The incidence of IMD across Europe has been relatively low over the past decade; of the countries that came together for the South-Eastern Meningococcal Advocacy Group, the notification rates were lower than the European average for some country. The age distribution of IMD cases was highest in infants and children, and most countries also had a further peak in adolescents and young adults. Across the nine included countries between 2010 and 2020, the largest contributors to IMD were serogroups B and C; however, each individual country had distinct patterns for serogroup distribution. Along with the variations in epidemiology of IMD between the included countries, vaccination policies also differ.