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Updated: Jun 27, 2025
A Murine Model of Group B Streptococcus Vaginal Colonization
Published on: November 16, 2016
Association between anti-capsular IgG levels at birth and risk of invasive group B streptococcus disease in Finnish
Annika Saukkoriipi1, Natalie C Silmon de Monerri2, Maija Toropainen3
1Finnish Institute for Health and Welfare, Oulu, Finland.
Insights
High levels of neonatal antibodies against Group B Streptococcus (GBS) correlate with reduced infant GBS disease risk in Finland. A maternal GBS vaccine is predicted to be highly effective in preventing invasive disease.
Area of Science:
- Neonatal immunology
- Infectious disease epidemiology
- Vaccine development
Background:
- Group B Streptococcus (GBS) is a significant cause of neonatal infections.
- Maternally transferred antibodies are linked to protection against infant GBS disease.
- Previous studies lacked infant sera and standardized assays for antibody concentration.
Purpose of the Study:
- To evaluate anti-GBS capsular polysaccharide IgG concentrations associated with protection against invasive GBS disease in Finnish infants.
- To assess the potential efficacy of a GBS vaccine based on antibody levels.
Main Methods:
- Retrospective case-control study using cord sera from the Finnish DIPP study (1995-2017).
- Included infants aged ≤6 months with GBS infection (55 cases) and matched healthy controls (229).
- Measured anti-GBS IgG (serotypes Ia-V) using a standardized immunoassay and analyzed disease risk with a Bayesian model.
Main Results:
- GBS serotype III was most common (58% of cases).
- Higher anti-serotype III IgG concentrations in controls than cases (p<0.001).
- Estimated 75-90% risk reduction for serotype III disease with 0.120-0.266 μg/mL IgG; maternal immunization predicted >80% efficacy for GBS6 vaccine.
Conclusions:
- Elevated neonatal anti-GBS capsular polysaccharide IgG at birth is associated with decreased infant GBS disease risk in Finland.
- A maternal GBS conjugate vaccine in development is predicted to be efficacious for disease prevention.
Background:
Group B streptococcus is a major cause of neonatal disease. Natural history studies have linked maternally transferred anti-group B streptococcus capsular polysaccharide antibodies with protection against infant group B streptococcus disease. Previous studies of capsular polysaccharide antibody concentration in European populations have used maternal (not infant) sera and a non-standardised assay. This study aimed to evaluate anti-capsular polysaccharide IgG concentrations associated with protection against invasive group B streptococcus disease in Finnish infants.
Methods:
In this retrospective case-control study, we used cord sera from the Finnish DIPP study repository, which was obtained between Jan 1, 1995, and Dec 31, 2017. We included infants aged 6 months or younger with group B streptococcus infection (cases) and healthy infants (controls). We enrolled infants with invasive neonatal group B streptococcus (55 cases) and matched controls (229 controls) aged 6 months or younger after identification from Finnish health registers. We measured anti-capsular polysaccharide IgG (serotypes Ia-V) concentration using a standardised immunoassay and we estimated its relationship to disease risk using a Bayesian model. We used the derived risk-concentration curve to predict potential efficacy of six-valent group B streptococcus capsular polysaccharide vaccine (GBS6) based on previously reported immunogenicity data.
Findings:
Most (32 [58%] of 55 cases) group B streptococcus cases were due to serotype III and anti-serotype III streptococcus capsular IgG concentrations were higher in serotype III-matched controls than in cases (p<0·001). 0·120-0·266 μg/mL serotype III-specific IgG was estimated to confer 75-90% risk reduction against serotype III disease. A universal risk-concentration curve, aggregating results across all six serotypes, yielded similar results. Application of this curve to GBS6 immunogenicity data predicted maternal immunisation to be more than 80% efficacious for prevention of infant group B streptococcus disease.
Interpretation:
Higher neonatal anti-capsular polysaccharide serum IgG concentration at birth correlated with reduced risk of infant group B streptococcus disease in Finland. Based on these results, a maternal group B streptococcus capsular conjugate vaccine currently in development is predicted to be efficacious.
Funding:
Pfizer.
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