Oral Presentation 25th International Pathogenic Neisseria Conference 2026

Genomic Epidemiology of Neisseria meningitidis in New Zealand Following 4CMenB Vaccination Implementation    (139989)

Sarah Hannah 1 2 , Una Ren 2 , Nigel French 1 3 , Alex Gavryushkin 4 , Hannah Cooper 2
  1. Tāwharau Ora | School of Veterinary Science, Massey University, Palmerston North, New Zealand
  2. Health security, New Zealand Institute for Public Health and Forensic Science, Wellington, New Zealand
  3. Te Niwha, the Infectious Diseases Research Platform, Otago, New Zealand
  4. Fold AI, UNSW RNA Institute, Sydney, NSW, Australia

New Zealand experiences higher rates of meningococcal disease than other high-income nations and group B (MenB) meningococcal disease has the highest incidence1. To address this, Bexsero® (4CMenB) was added to the national immunisation schedule in March 2023, with doses administered at 3 months, 5 months, and a booster at 12 months2, alongside a catch-up programme for all children under five years of age The vaccine is also funded for individuals aged 13–25 years entering close‑living situations3.

This study describes the genomic epidemiology of Neisseria meningitidis in New Zealand following the introduction of Bexsero, to understand changes in response to vaccination. As Bexsero targets outer membrane proteins and other surface-exposed proteins that are not exclusive to MenB, all meningococcal groups were included in analyses. Whole-genome sequencing data from 98 invasive meningococcal isolates collected between 2023 and 2025 in New Zealand were analysed to assess genetic relatedness and potential shifts in circulating lineages following vaccine introduction.

Genetic relatedness among isolates was examined using a single nucleotide polymorphism-based maximum likelihood phylogeny, annotated with variants of outer membrane vesicle components and surface-exposed proteins included in the Bexsero vaccine. Year-to-Year comparisons of the protein variants were used to identify temporal change in frequency of vaccine relevant proteins. Predicted vaccine antigen reactivity was assessed using the MenDeVAR (Meningococcal Deduced Vaccine Antigen Reactivity) Index4-5. 63.54% of isolates had insufficient data to categorise Bexsero® reactivity; however, only 6.25% showed no predicted reactivity, while 73% were predicted to be reactive to Trumenba®, and no isolates showed complete non-reactivity. To contextualise genomic findings, national vaccination coverage data were analysed by age group. By the end of 2023, 87% of infants (<1yrs) had received a first dose and 55% a second dose. Coverage increased in infants from 2024 and 2025. Uptake amongst children aged 1–4 years was lower. Age-specific vaccination uptake was examined alongside genomic data to investigate changes in meningococcal epidemiology following the introduction of Bexsero in New Zealand.

This study provides insight into how N. meningitidis populations in New Zealand are responding to the introduction of Bexsero and will inform future meningococcal disease control and public health strategies.

  1. Burton, C., et al., Pediatric Invasive Meningococcal Disease, Auckland, New Zealand (Aotearoa), 2004–2020. Emerging Infectious Diseases, 2023. 29(4): p. 686-695.
  2. Pharmac, Decision to widen access to the meningococcal B multicomponent vaccine for children under 5 years of age. 2025, PHARMAC: Wellington, New Zealand.
  3. Immunisation Advisory Center, Meningococcal B (Bexsero) quick facts, Immunisation Advisory Center, Editor. 2024.
  4. Rodrigues, C.M.C., et al., Meningococcal Deduced Vaccine Antigen Reactivity (MenDeVAR) Index: a Rapid and Accessible Tool That Exploits Genomic Data in Public Health and Clinical Microbiology Applications. J Clin Microbiol, 2020. 59(1).
  5. Jolley, K.A., J.E. Bray, and M.C.J. Maiden, Open-access bacterial population genomics: BIGSdb software, the PubMLST.org website and their applications. Wellcome Open Res, 2018. 3: p. 124.