Assessing the burden of diseases potentially preventable by maternal immunization in Sub-Saharan Africa

Photo Credit: Flickr: Kate Holt/MCSP

Introduction
This study aims to quantify the burden of four potentially vaccine-preventable diseases in pregnant women and their infants in sub-Saharan Africa. This population-based prospective cohort study in Ghana and Zimbabwe will focus on Group B streptococcus (GBS), Respiratory Syncitial Virus (RSV), Influenza and Pertussis (GRIP) and will end in December 2019.

The field studies will be implemented by the Centre for Maternal and Newborn Health with two research centres - the Kintampo Health Research Centre (KHRC) in Ghana and the Centre for Sexual Health and HIV/AIDS Research (CeSHHAR) in Zimbabwe; and two collaborating laboratories – Public Health England (PHE) and University of Wits’ Respiratory and meningeal Pathogens Research Unit (RMPRU).

Brief background
Globally, child deaths have declined substantially in recent years. This is ascribed to improved management of infections (diarrhoea and pneumonia) and high immunisation coverage. However, infections still account for nearly one third of all newborn deaths. Many of these are preventable. Infections or vaccine administration in pregnancy leads to antibody production, and if these are passed onto the unborn baby, may protect it against disease. Pregnant women are therefore potential channels to protect infants in early life before they commence routine immunisation.

Vaccines already exist for influenza and pertussis (GRIP), but current immunisation schedules in low- and middle-income countries (LMICs) do not include the two vaccines. No vaccines are currently licensed for GBS and RSV. Before making a case for introduction of vaccinations against GRIP in sub-Saharan LMICs, it is important to quantify the burden and estimate the cost-effectiveness of other strategies to address this burden.

Activities
The study design will be informed by a systematic review of literature to assess the current knowledge and identify gaps. The research will involve approximately 1200 women in Ghana and Zimbabwe, who will be enrolled before 28 weeks of pregnancy and followed until the end of the pregnancy. For every livebirth, the study will follow the infant for the first year of life.

The data will be collected by trained research assistants, who will conduct morbidity surveillance either through home visits or phone contacts. These workers will actively screen mothers for signs and symptoms of urinary tract infections (UTIs) or influenza-like illnesses (ILIs), screen their infants for ILIs or signs of sepsis (suggestive of GRIP infections) and look for infections in pregnancies ending in a stillbirth or preterm birth.

The findings from the study will be used to develop recommendations for the prioritisation of vaccines, inform the investment case for vaccines for GRIP organisms and initiate discussions with appropriate stakeholders on ways to make maternal immunisation accessible to these populations.