Oral Presentation Lancefield International Symposium for Streptococci and Streptococcal Diseases 2025

Protection against invasive group B streptococcus disease in young infants: a multi-country analysis of five serocorrelate studies (118581)

Liberty Cantrell 1 2 , Natasha Thorn 3 , Kostas Karampatsas 3 , Mary Kyohere 3 4 , Madeleine Cochet 3 , Tom Hall 3 , Simon Beach 3 , Emily Bentley 3 , Olwenn Daniel 3 , Cemal Cagil Kocana 3 , Alane Izu 5 , Shabir Madhi 5 , Merijn W Bijlsma 6 , Alberto Berardi 7 , Robert Mboizi 4 8 , Paul T Heath 3 , Kirsty Le Doare 3 , Merryn Voysey 1 2
  1. Oxford Vaccine Group, Department of Paediatrics, University of Oxford, Oxford, UK
  2. NIHR Oxford Biomedical Research Centre, Oxford, UK
  3. Centre for Neonatal and Paediatric Infection & Vaccine Institute, City St George’s, University of London, London, UK
  4. Makerere University-Johns Hopkins University Research Collaboration, Kampala, Uganda
  5. WITS-VIDA, Johannesburg, South Africa
  6. Amsterdam UMC, location University of Amsterdam, Amsterdam, The Netherlands
  7. Azienda Ospedaliero-Universitaria di Modena, Modena, Italy
  8. Faculty of Medicine and Health Sciences, University of Antwerp, Antwerp, Belgium

Background:

Group B streptococcus (GBS) is a leading cause of neonatal infection and meningitis. This study aims to quantify the relationship between risk of invasive GBS (iGBS) and serotype-specific antibody levels in infants across African and European settings.

Methods:

Data from cases and controls were combined for analysis from studies in South Africa (N=77 cases/N=250 controls), Uganda (N=19/69), UK (N= 167/274), Italy (N= 41/293), and the Netherlands (N=102/42). Cases were infants <90 days of age with iGBS and controls were healthy infants born to mothers colonised with GBS in pregnancy. Serotype-specific anti-capsular polysaccharide IgG antibody at birth (cord) or at the time of disease (acute sample) was quantified via a standardised multiplex immunoassay. Risk curves were generated using logit models adjusted for country.

Results:

Preliminary data from 406 cases and 928 controls were included. 231 (57%) cases were early onset disease (EO: 0-7 days), 165 (41%) were late onset disease (LO: 8-89 days). Serotype III cases were most prevalent (N=225). Serotype III antibody concentrations of 0.117 µg/mL (95% CI 0.06, 0.24) was associated with an 80% reduction in disease risk in the first three months of life. For serotype Ia an 80% risk reduction was demonstrated with antibody concentrations of 1.97 (95% CI 0.65, 5.9) µg/mL. Higher antibody concentrations were seen in EO disease compared with LO. No clear differences in antibody concentrations were observed between high and low-income settings.

Conclusions:

Antibody concentrations at birth are similar across diverse geographies and findings are consistent with those seen in other studies.