Immunological protection against invasive infant group B streptococcal disease (iGBS): preliminary data from a UK case control study — ASN Events
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  2. Plenary 10 - Invasive Disease
  3. Immunological protection against invasive infant group B streptococcal disease (iGBS): preliminary data from a UK case control study

Immunological protection against invasive infant group B streptococcal disease (iGBS): preliminary data from a UK case control study (117991)

Natasha Thorn 1 , Kostas Karampatsas 1 , Liberty Cantrell 2 , Mary Kyohere 1 , Madeleine Cochet 1 , Tom Hall 1 , Olwenn Daniel 1 , Simon Beach 1 , Emily Bentley 1 , Cemal Ҫağil Koҫana 1 , Kate Walker 3 , Asma Khalil 1 , Jane P Daniels 3 , Jane Plumb 4 , Nick Andrews 5 , the iGBS3 Study Group 6 , Merryn Voysey 2 , Kirsty Le Doare 1 , Paul T Heath 1
  1. Centre for Neonatal and Paediatric Infection & Vaccine Institute, City St George’s, University of London, London, United Kingdom
  2. Oxford Vaccine Group, Oxford, United Kingdom
  3. Nottingham Clinical Trials Unit, School of Medicine, University of Nottingham, Nottingham, United Kingdom
  4. Group B Strep Support (GBSS), Haywards Heath, United Kingdom
  5. Immunisation and Vaccine Preventable Diseases Division, UK Health Security Agency, London, United Kingdom
  6. the iGBS3 Study Group, UK Wide Investigators

Background:

Group B streptococcus (GBS) is a leading cause of neonatal infection and meningitis. Defining an immunological endpoint would enable licensure of vaccine candidates. This study aims to delineate the relationship between serotype-specific antibody and infant invasive GBS (iGBS) risk.

Methods:

A multicentre, unmatched, case-control study stratified by serotype. Cases were infants <90 days of age with iGBS (sterile site isolate), controls were infants without iGBS, born to those GBS swab-positive in pregnancy. Cord sera (where available), GBS isolates, clinical data and acute sera (cases) were collected. Evaluable participants required dataset, isolate and serum. Isolates were serotyped via whole genome sequencing and/or polymerase-chain-reaction. Serotype-specific anti-capsular polysaccharide IgG antibody was quantified via standardised multiplex immunoassay. Quantification and functional assay of AlpN protein IgG is planned. Initial analysis compared concentrations between cases and controls by serotype. Further analysis will assess relationship of antibody concentration with being a case using logistic regression, and concentrations associated with 80% risk reduction via scaled logit model.

Results:

57 sites across England recruited 219 cases and 398 controls (168 and 286 currently evaluable, respectively). Cases were 60% EO (median onset 0 days), 40% LO (median onset 30 days). 79 (48%) cases were serotype III, 23 (14%) Ia, with the remainder similarly distributed between serotypes. Preliminary data shows lower antibody concentrations in cases than controls for 4/6 tested serotypes (Ia, II, III, IV).

Conclusions:

This study provides initial UK data on antibody and relative disease risk for infant iGBS, supporting a potential immunological approach to vaccine licensure.

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