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Cover of Developing a serocorrelate of protection against invasive group B streptococcus disease in pregnant women: a feasibility study

Developing a serocorrelate of protection against invasive group B streptococcus disease in pregnant women: a feasibility study

Health Technology Assessment, No. 23.67

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Author Information
Southampton (UK): NIHR Journals Library; .

Headline

This study assessed key operational aspects of study design needed to determine the correlates of protection against invasive group B streptococcus and confirmed that a full study is feasible.

Abstract

Background:

Group B streptococcus is the leading cause of infection in infants. Currently, intrapartum antibiotic prophylaxis is the major strategy to prevent invasive group B streptococcus disease. However, intrapartum antibiotic prophylaxis does not prevent maternal sepsis, premature births, stillbirths or late-onset disease. Maternal vaccination may offer an alternative strategy. Multivalent polysaccharide protein conjugate vaccine development is under way and a serocorrelate of protection is needed to expedite vaccine licensure.

Objectives:

The ultimate aim of this work is to determine the correlate of protection against the major group B streptococcus disease-causing serotypes in infants in the UK. The aim of this feasibility study is to test key operational aspects of the study design.

Design:

Prospective cohort study of pregnant women and their infants in a 6-month period (1 July to 31 December 2018).

Setting:

Five secondary and tertiary hospitals from London and South England. National iGBS disease surveillance was conducted in all trusts in England and Wales.

Participants:

Pregnant women aged ≥ 18 years who were delivering at one of the selected hospitals and who provided consent during the study period. There were no exclusion criteria.

Interventions:

No interventions were performed.

Main outcome measures:

(1) To test the feasibility of collecting serum at delivery from a large cohort of pregnant women. (2) To test the key operational aspects for a proposed large serocorrelates study. (3) To test the feasibility of collecting samples from those with invasive group B streptococcus.

Results:

A total of 1823 women were recruited during the study period. Overall, 85% of serum samples were collected at three sites collecting only cord blood. At the two sites collecting maternal, cord and infant blood samples, the collection rate was 60%. A total of 614 women were screened for group B streptococcus with a colonisation rate of 22% (serotype distribution: 30% III, 25% Ia, 16% II, 14% Ib, 14% V and 1% IV). A blood sample was collected from 34 infants who were born to colonised women. Maternal and infant blood and the bacterial isolates for 15 newborns who developed invasive group B streptococcal disease during the study period were collected (serotype distribution: 29% III, 29% II, 21% Ia, 7% Ib, 7% IV and 7% V).

Limitations:

Recruitment and sample collection were dependent on the presence of research midwives rather than the whole clinical team. In addition, individualised consent limited the number of women who could be approached each day, and site set-up for the national surveillance study and the limited time period of this feasibility study limited recruitment of all eligible participants.

Conclusions:

We have verified the feasibility of collecting and processing rectovaginal swabs and blood samples in pregnant women, as well as samples from those with invasive group B streptococcal disease. We have made recommendations for the recruitment of cases within the proposed GBS3 study and for controls both within GBS3 and as an extension of this feasibility study.

Future work:

A large case–control study comparing specific immunoglobulin G levels in mothers whose infants develop invasive group B streptococcal disease with those in colonised mothers whose infants do not develop invasive group B streptococcal disease is recommended.

Trial registration:

Current Controlled Trials ISRCTN49326091; IRAS project identification number 246149/REC reference number 18/WM/0147.

Funding:

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 23, No. 67. See the NIHR Journals Library website for further project information.

Contents

About the Series

Health Technology Assessment
ISSN (Print): 1366-5278
ISSN (Electronic): 2046-4924

Article history

The research reported in this issue of the journal was funded by the HTA programme as project number 17/153/01. The contractual start date was in April 2018. The draft report began editorial review in February 2019 and was accepted for publication in August 2019. The authors have been wholly responsible for all data collection, analysis and interpretation, and for writing up their work. The HTA editors and publisher have tried to ensure the accuracy of the authors’ report and would like to thank the reviewers for their constructive comments on the draft document. However, they do not accept liability for damages or losses arising from material published in this report.

Declared competing interests of authors

Kirsty Le Doare has received a travel grant from Pfizer (New York, NY, USA). Paul Heath is an investigator for clinical trials (not group B streptococcus-specific) who carries out work on behalf of St George’s, University of London, and is sponsored by various vaccine manufacturers, including Novartis (Basel, Switzerland), Pfizer and GlaxoSmithKline plc (Brentford, UK). Asma Khalil has been a member of the Health Technology Assessment General Committee since November 2018, and is due to be active until 2022.

Last reviewed: February 2019; Accepted: August 2019.

Copyright © Queen’s Printer and Controller of HMSO 2019. This work was produced by Carreras-Abad et al. under the terms of a commissioning contract issued by the Secretary of State for Health and Social Care. This issue may be freely reproduced for the purposes of private research and study and extracts (or indeed, the full report) may be included in professional journals provided that suitable acknowledgement is made and the reproduction is not associated with any form of advertising. Applications for commercial reproduction should be addressed to: NIHR Journals Library, National Institute for Health Research, Evaluation, Trials and Studies Coordinating Centre, Alpha House, University of Southampton Science Park, Southampton SO16 7NS, UK.
Bookshelf ID: NBK551316DOI: 10.3310/hta23670

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