PREPARE Work Package 3 -Development of a Serocorrelate of Protection Against GBS - Protocol Harmonisation.

Group B Streptococcus (GBS) causes severe infections in young infants across the world. In 2015 it was estimated that there were at least 319,000 infants under three months of age with GBS disease worldwide, resulting in 90,000 deaths and at least 10,000 children with long term disabilities. Around 20% of all pregnant women carry GBS in their vagina and bowel, and babies are exposed to GBS bacteria around the time of birth. The options for prevention are currently limited to offering antibiotics during labour.

A vaccine that could be given to pregnant women has the greatest potential to benefit mothers and babies worldwide. There are vaccines currently being tested in clinical trials, including in pregnant women. Given the complexity, size and costs associated with a phase III trial, it is generally agreed that indirect evidence (correlates) of protection (CoP), based on immunologic data from vaccine and seroepidemiological studies, opsonophagocytic assays and supported by animal models, could be pivotal for vaccine licensure, with effectiveness subsequently confirmed in post-licensure evaluations.

This study aims to develop a biobank of sera from 150 cases of serotype III GBS disease and associated clinical information from seven countries (Malawi, Uganda, UK, the Netherlands, Italy and France) with 3:1 (450) serotype matched healthy controls.

GBS cases will be identified through active surveillance of GBS disease in infants, as part of ongoing epidemiological studies in Uganda, the UK, Italy, France, the Netherlands and Malawi. Upon identification of cases, consent will be requested to obtain a serum sample (1-2 mL of blood collected from infant), the GBS isolate and to collect brief clinical and demographic details. Each site will aim to collect around 50 cases of invasive GBS disease cases (with all samples) over the course of 2 years.

Each site will also recruit approximately 1000 women to have a rectovaginal swab at 35-37 weeks gestation and cord and maternal blood samples at delivery. These women and their infants will be followed up to 90 days of age and considered appropriate controls if the infants are exposed to the same serotype/strain of GBS at delivery as the case - but do not develop GBS the first 90 days of life. We will select 3 controls for every case.