Colonization of the human nasopharyngeal tract by the bacterium Neisseria meningitidis is usually asymptomatic, but life-threatening meningococcal disease with a clinical presentation of meningitis, septicemia, or more rarely, gastrointestinal symptoms, can develop. Invasive meningococcal disease (IMD) can be fatal within 24 hours, but IMD is vaccine-preventable. Vaccines used to protect against IMD caused by 5 of the 6 most common serogroups (A, B, C, W, and Y) may also influence carriage prevalence in vaccinated individuals. Lower carriage among vaccinated people may reduce transmission to nonvaccinated individuals to provide herd protection against IMD. This article reviews observational and clinical studies examining effects of vaccination on N. meningitidis carriage prevalence in the context of mass vaccination campaigns and routine immunization programs. Challenges associated with carriage studies are presented alongside considerations for design of future studies to assess the impact of vaccination on carriage.

Recombinant surface protein meningococcal serogroup B (MenB) vaccines are available but with different antigen compositions, leading to differences between vaccines in their immunogenicity and like...

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.

Invasive meningococcal disease (IMD) is a global health threat with an unpredictable epidemiology that varies regionally and over time. During the COVID-19 pandemic, the Invasive Respiratory Infection Surveillance Consortium reported widespread reductions in bacterial diseases transmitted via the respiratory route, including IMD, that were associated with the stringency of COVID-19 measures implemented in each country. Here, we report the epidemiology of IMD from the United States, England, France, Australia, and Chile during and after the COVID-19 pandemic. There was a consistent trend in which IMD incidence declined throughout 2020 and into 2021 but began to increase in 2021 (England and Chile) or 2022 (United States, France, and Australia). Case numbers of IMD in France and the United States surpassed pre-pandemic levels by December 2022 and 2023, respectively, whereas in other countries examined, overall cases in 2021/2022 or 2023 approached but did not exceed pre-pandemic levels. Except for the United States, meningococcal serogroup B was the prominent serogroup of post-pandemic re-emergence, although substantial increases in serogroup Y and W disease in France in 2022 and serogroup W disease in Chile in 2023 were also observed. In the United States, where meningococcal vaccination coverage did not decline during the pandemic, the rebound in cases was predominantly due to serogroups C, Y, and nongroupable serogroups. The data indicate that surveillance of IMD cases, associated serogroups, and vaccination uptake is essential for monitoring the effectiveness of disease prevention strategies and guiding future public health policy.