Group B streptococcal disease in infants 0–3 months in The Netherlands, 1987–2023: a nationwide genomic and epidemiological surveillance study

Background Group B Streptococcus (GBS) is the leading cause of sepsis and meningitis in infants.The molecular epidemiology and potential vaccine coverage of GBS disease in infants was assessed in the Netherlands over a 37-year period. MethodsThis nationwide observational study identified infants aged 0-89 days with GBS culture-positive sepsis or meningitis between July 1987 and June 2024, through Dutch surveillance.Serotype was determined by latex agglutination.Whole-genome sequencing determined the clonal complex (CC) using multi-locus sequence typing (MLST) and identified virulence factors associated with meningitis.Strain coverage by the maternal vaccines GBS6 and GBS-AlpN were analysed.Findings 2212 episodes were identified; 1307 (59%) early onset disease (0-6 days) and 905 (41%) late onset disease (7-89 days).Mean annual incidence was 033 per 1000 live births and significantly increased from 019 in 1987 to 057 in 2023 due to an increase in sepsis cases (p < 00001).Serotype data was available for 2163 (98%) of 2212 isolates, of which serotype III was most common (1316/2163; 61%), followed by Ia (383/2163; 18%) and II (123/2163; 6%).MLST data was available for 1723 (78%) isolates; CC17 was most common (705/1723; 41%).CC17 increased from 29% (90/308) in 1987-1996 to 49% (262/538) in 2014-2023 (p < 00001).97% (2095/2163) of cases would be covered by the GBS6 vaccine, and 99% (1709/1723) by GBS-AlpN.Interpretation GBS disease is still increasing in the Netherlands.The GBS6 and GBS-AlpN vaccines would potentially prevent >96% of cases.