Group B streptococcus (GBS) is a leading cause of young infant mortality and morbidity globally, with vaccines being developed for over four decades but none licensed to date. A serocorrelate of protection against invasive disease in young infants is being considered to facilitate vaccine early licensure, followed by demonstration of efficacy assessed postlicensure. In this Review, we synthesise the available scientific evidence to define an immune correlate associated with GBS disease risk reduction on the basis of studies of natural infection. We summarise studies that have investigated GBS serum anticapsular or anti-protein antibodies, and studies measuring the association between antibody function and disease risk reduction. We highlight how knowledge on the development of correlates of protection from existing vaccines could be harnessed to facilitate GBS vaccine development. These lessons include aggregation of serocorrelates of protection for individual serotypes, understanding the relationship between immunity derived from natural exposure of adults and vaccine-induced immunity, or using extrapolation of protection from in-vitro immunoassay results. We also highlight key considerations for the assessment of the role of antibodies to derive a serocorrelate of risk reduction in future seroepidemiological studies of GBS disease.
Bibliographical noteFunding Information:
This Review was funded by a grant ( OPP1119788 ) from the Bill & Melinda Gates Foundation .
KLD has received an honorarium travel grant from Pfizer. BK directs IMmunising PRegnant women and INfants neTwork (IMPRINT), funded by the Global Challenges Research Fund Networks in Vaccines Research and Development that was co-funded by the UK Medical Research Council (MRC), the Biotechnology and Biological Sciences Research Council, and the National Vaccine Program Office; and is the theme leader at the MRC unit in The Gambia that has previously received funding for vaccine trials, including vaccines produced by Pfizer and GSK. PTH is an investigator for clinical trials done on behalf of St George's Hospital, St George's University of London, UK, sponsored by various vaccine manufacturers, including Novartis, Pfizer, and GSK, and has been a consultant to Novartis and Pfizer on GBS vaccines, but received no personal funding for these activities. DG participates in advisory boards and consultancies for vaccine manufacturers, including Merck, Sanofi Pasteur, and GSK. CB has been an adviser to GSK and Pfizer. MSE has received a research grant from Pfizer. GK has received funds from Pfizer to attend a meeting. AStM is an employee of the Bill & Melinda Gates Foundation, which funded this Review. ASA is employed by Pfizer and owns stock in the company. BC is employed by the GSK group of companies and owns stock of the GSK group of companies. The phase 2 studies investigating the trivalent CRM 197 conjugate GBS vaccine were initially supported by Novartis Vaccines and Diagnostics, before the divestiture of its non-influenza vaccine business, which was acquired by GSK Biologicals in March, 2015. PF is an employee of Minervax and owns stock in the company. AG has received a grant for meeting travel from Pfizer. SAM, JV, MHN, and NA have nothing to declare.
© 2019 Elsevier Ltd