Association between anti-capsular IgG levels at birth and risk of invasive group B streptococcus disease in Finnish newborns: a retrospective case–control study
Annika Saukkoriipi PhD , Natalie C Silmon de Monerri PhD , Maija Toropainen PhD , Laura Lindholm MSc , Riitta Veijola MD PhD , Jorma Toppari MD PhD , Mikael Knip MD PhD , David Radley MSc , Emily Gomme PhD , Babalwa Jongihlati MD , Annaliesa S Anderson PhD , Arto A Palmu MD PhD , Raphael Simon PhD
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引用次数: 0
Abstract
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.
期刊介绍:
The Lancet Microbe is a gold open access journal committed to publishing content relevant to clinical microbiologists worldwide, with a focus on studies that advance clinical understanding, challenge the status quo, and advocate change in health policy.