Medical Academic (MA): How would you describe the current epidemiology of IMD in South Africa, including any recent shifts in incidence, outbreak patterns, and serogroup distribution?

Prof Brian Eley (BE): Invasive meningococcal disease (IMD) is caused by a bacterium called Neisseria meningitidis. There are twelve groups (or serogroups) of Neisseria meningitidis classified according to differences in the bacterial polysaccharide, a component of the bacterial outer structure. Seven of the twelve serogroups (serogroups A, B, C, W, X, Y and Z) are pathogenic and can cause IMD.

During the last few decades, serogroup X has become an important cause of IMD in sub-Saharan Africa but to date has not caused many infections in South Africa. The percentage of IMD caused by the different serogroups fluctuates from year to year.

During the last few years serogroup B has been the main cause of IMD, responsible for 45-50% of IMD cases globally. Currently, serogroup B causes human infection in most provinces of South Africa, including Gauteng, Western Cape, Eastern Cape, and KwaZulu-Natal. In South Africa, IMD is an endemic infection with cases occurring throughout the year, but the number of cases increases during colder months of the year.

Additionally, outbreaks of IMD may occur periodically but the timing of outbreaks is difficult to predict. Settings, in which outbreaks have been documented include army barracks and school hostels.

IMD is a serious infection that mainly manifests clinically with meningitis and / or a more serious form of infection called septicaemia. Despite starting appropriate treatment the overall case fatality rate may be as high as 15% and 10-20% of survivors will experience long-term, disabling sequelae.

Prof Nicolette du Plessis (NdP): Meningococcal disease is a category 1 notifiable medical condition (NMC). All clinically suspected cases must be notified immediately to the local or district health department to facilitate urgent contact tracing. National, active and passive, laboratory-confirmed invasive meningococcal disease surveillance has been ongoing since 2003 through the GERMS-SA surveillance programme of the National Institute for Communicable Diseases. Meningococcal disease is endemic to South Africa, occurring all year round with a peak from June to October. 

In 2024, 150 cases of invasive meningococcal disease (IMD) were reported in South Africa, a 40% increase from 2023 (n=107) and the highest incidence (0.24 per 100 000) seen in recent years, surpassing pre-pandemic levels. The Western Cape had the highest incidence, and over half of cases occurred in children under 15 years of age, with infants <1 year of age (2.4 episodes per 100 000) showing the greatest risk.

In 2025: 148 cases of invasive Neisseria meningitidis (IMD) were reported; the highest incidence still in the Western Cape, followed by Gauteng; and serogroup B dominating. 1 January 2026 – 22 February 2026: A total of 11 confirmed meningococcal disease cases (including 1 death) was reported in the Western Cape. Eight cases were recorded in the Cape Town Metro district, two cases in Cape Winelands, and one case in the Overberg District. The majority of reported cases were below the age of one year. These cases were sporadic and do not constitute an outbreak.  

Prevalent strains (2024–2025): Recent data shows serogroup B remains dominant, particularly in infants. Age profile: Infants (<1 year) have the highest incidence, followed by a secondary peak in the 15–24 year age group. Regional focus: The Western Cape has historically reported higher incidence rates compared to other provinces. 

MA: Given the local serogroup landscape, what makes serogroup B meningococcal disease particularly concerning from a clinical and public health perspective?

NdP: Serogroup B remains a clinical concern because it can cause severe illness in very young children (<1-year of age), progressing extremely rapidly, sometimes within hours, leading to severe illness or even death if not treated promptly. Early symptoms may be mild and non-specific, making early diagnosis difficult and increasing the risk of delayed treatment. From a public health perspective, it can spread unpredictably and is not routinely covered by standard South African EPI vaccines nor is it covered by the meningococcal conjugate vaccine (protecting against serogroups A, C, W, and Y) that has been available in the private sector since 2014.

BE:  Other than becoming the dominant disease-causing serogroup, serogroup B behaves like all other pathogenic meningococcal serogroups causing a similar spectrum and severity of clinical infection, and it has the potential to cause both endemic infection and outbreaks. The first serogroup B vaccine was registered in South Africa by the South African Health Products Regulatory Authority (SAPHRA) in July 2023 and became available in the private sector from 2025 onwards. Before 2025, primary prevention through vaccination against serogroup B was not possible in South Africa, whereas vaccination against serogroups A, C, W and Y has been possible since the 1980s.

MA: Which populations are currently at highest risk in South Africa, and how should clinicians practically stratify risk across age groups such as infants, children, and adolescents?

BE: Infants and young children are particularly as risk of serious infection. Persons at high risk of acquiring IMD include children and adults living with HIV infection, those with immune deficiencies such as splenic dysfunction and complement, deficiencies, travellers to high risk settings such as countries in the African Meningitis Belt, and healthy individuals and health care personnel in contact with patients with IMD. Meningococcal vaccines currently available in South Africa can prevent IMD caused by serogroups A, B, C, W and Y thus reducing the risk of IMD.

NdP: Infants are at highest risk of severe illness, while teenagers are key drivers of spread (play an important role in transmission) —making early recognition and rapid treatment essential across all age groups. Infants under 1-year of age (highest risk): This is the most affected group nationally. Their immune systems are still developing, and they are more likely to develop severe, rapidly progressing disease. Young children (1–5 years): Risk remains elevated compared to older children, particularly in those: Attending crèches or early childcare settings; and underlying conditions (e.g. HIV, immunodeficiency). Adolescents and young adults: This group carries and transmits the bacteria more frequently, even when well. Risk increases in: Boarding schools, universities, or crowded living environments. Social settings with close contact (eg shared accommodation).

MA: How should clinicians approach prevention in the context of available vaccines — particularly balancing coverage of A, C, W, and Y serogroups versus targeted protection against serogroup B?

NdP: There is no single vaccine that covers all meningococcal strains—clinicians must combine broad protection (A, C, W, Y) with targeted decisions about serogroup B, particularly for infants and high-risk individuals. Meningococcal vaccination is one of the most important travel vaccines—especially for high-risk destinations and mass gatherings—with MenACWY forming the backbone of protection.

BE: Routine vaccination against serogroups A, B, C, W and Y is not part of the Expanded Programme on Immunisation in South Africa (EPI-SA) and therefore unavailable in the public sector. In contrast, routine vaccination schedules have been developed for infants and young children receiving care the private sector and are widely used in this setting. There are currently no recommendations for catch-up meningococcal vaccination for children more than two years of age in South Africa. For older children and adults who are at high risk of IMD and serviced by the private sector vaccination is recommended   Whereas, within the public sector vaccination against serogroup A, C, W and Y infection is possible using the first generation meningococcal polysaccharide vaccines but only for patients with selective immune deficiencies such as splenic dysfunction and complement deficiencies.

MA: Looking ahead, how do you anticipate serogroup distribution evolving, and what would an ideal national prevention strategy look like?

BE: Serogroup distribution has never been static and will undoubtedly continue to evolve over time. Serogroup B has consistently been the dominant IDM-causing serogroup in the Western Cape and Eastern Cape. In contrast, serogroup distribution varies in other provinces.

For example, in Gauteng, serogroup W was dominant from 2006 until 2016, serogroup B in 2017 and 2018, serogroup W in 2019, serogroup B in 2020 and 2021, serogroup Y in 2022 and serogroup B in 2023 and 2024. These general patterns are likely to continue for the foreseeable future.

Prevention is not limited to vaccination. Secondary prevention for persons in close contact with a case of IMD using specific antibiotic interventions is routinely practiced in both public and private sectors of South Africa and globally, as it controls the spread of IMD to disease-free child and adult contacts.

Ideally routine vaccination (a primary prevention strategy) should be administered to all South African infants and persons at high risk for IMD. This is not possible within the public sector because IMD is a relatively uncommon infection which may result in a relatively high cost-benefit ratio, meningococcal vaccines are very expensive requiring large annual budgets, and there are many health priorities in South Africa are deemed to be more important than IMD and to which limited public sector resources are directed. 

NdP: South Africa’s meningococcal future is likely to remain mixed, with serogroup B staying prominent but not replacing the others completely. The ideal response is not one vaccine or one policy, but a smarter national package: better surveillance, more strategic use of MenACWY and MenB vaccines, targeted protection for high-risk groups, and ongoing clinician education so that healthcare workers recognise and treat the disease earlier. The WHO ‘Defeating Meningitis by 2030’ roadmap emphasises vaccines, better diagnosis and treatment, and stronger education and training for health workers.

Prof Brian Eley is a paediatric infectious diseases sub-specialist based in Cape Town. He has served as Head of Infectious Diseases at Red Cross War Memorial Children’s Hospital and Head of Clinical Immunology until March 2025 when he retired from his clinical position. His research interests include paediatric HIV treatment outcomes, novel tuberculosis diagnostics, bloodstream infections, vaccine safety, and inborn errors of immunity. He has held multiple advisory and leadership roles in WHO and African and global paediatric infectious diseases organisations, contributing to policy development, training, and clinical service advancement. He is the current President of the World Society for Pediatric Infectious Diseases.

Prof Nicolette du Plessis, a registered Paediatric Infectious Diseases Specialist, is an Associate Professor and Head of the Paediatric Infectious Diseases Division of the Department of Paediatrics at the University of Pretoria and Kalafong Hospital. Her interests and research in the field of Paediatric Infectious Diseases lead to her PhD, which focused on early HIV diagnosis and treatment. Other interests include immunology, allergology, travel medicine, tuberculosis, immunisation and vaccine-preventable diseases, outbreak investigation, and antibiotic stewardship. Her recent research projects focus on paediatric Covid-19 and HIV. She is currently the president of Federation of Infectious Diseases Societies of Southern Africa, and she serves on numerous advisory boards both locally and nationally.

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