The Vaccines & Immunity theme works towards a better understanding of natural or vaccine-induced immunity implicated in defence against serious infectious diseases, including tuberculosis. Our studies in lab and field aim to inform the design of novel vaccines and maximise vaccine impact. We have developed a portfolio of discovery science and impact projects around this ambition. Using the core support structures and the diversity of skills of the leading investigators within the theme, we place the following questions at the centre of our work:

• What kind of immune responses should vaccines elicit to induce maximal protection?


• Can we identify correlates of protection urgently required to develop novel vaccines against pathogens requiring elimination by cell mediated immunity, e.g. M.tuberculosis


• Which vaccines are safe, immunogenic and effective in the long term in resource poor settings and how are they best used within the EPI program?

Through the conduct of both laboratory science and clinical trials, we aim to contribute to the evidence based development and delivery of vaccines. We aim to enhance the value of our clinical trials by gaining mechanistic insights into immune responses and age-dependent immune development in the context of vaccination, infection and important epidemiological and pathogen-derived co-factors. In the laboratory, we employ cutting edge immunological and systems biology tools to dissect compartments of the immune response in the context of infection and vaccination. In addition to the clinical trials, our field studies follow longitudinal observational cohorts. These include entire households and mother/infant pairs as platforms to investigate host responses in individuals of different ages, and to dissect the interactions between host and pathogen under vaccine or disease pressures.

Theme Leader

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Oral azithromycin given during labour decreases bacterial carriage in the mothers and their offspring: a double-blind randomized trial

Bacterial sepsis remains a leading cause of death among neonates with Staphylococcus aureus, Group B Streptococcus (GBS) and Streptococcus pneumoniae identified as the most common causative pathogens in Africa. Asymptomatic bacterial colonization is an intermediate step towards sepsis. We conducted a phase-III, double-blind, placebo-controlled randomized trial to determine the impact of giving one oral dose of azithromycin to Gambian women in labour on the nasopharyngeal carriage of S. aureus, GBS or S. pneumoniae in the newborn at day 6 post-partum. Study participants were recruited in a health facility in Western Gambia. They were followed during 8 weeks and samples were collected during the first 4 weeks. Between April 2013-2014, we recruited 829 women who delivered 843 babies, including 13 stillbirths. Sixteen babies died during the follow-up period. No maternal deaths were observed. No serious adverse events related to the intervention were reported. According to the intention-to-treat analysis, prevalence of nasopharyngeal carriage of the bacteria of interest in the newborns at day 6 was lower in the intervention arm [65.1% versus 28.3% – Prevalence Ratio (PR)=0.43; 95%CI: 0.36-0.52, p<0.001]. At the same time point, prevalence of any bacteria in the mother was also lower in the azithromycin group [nasopharynx (40.0% versus 9.3%, p<0.001); breast milk (21.6% versus 7.9%, p<0.001); and the vaginal tract (24.2% versus 13.2%, p<0.001)]. Differences between arms lasted for at least 4 weeks. Oral azithromycin given to women in labour decreased carriage of bacteria of interest in mothers and newborns and may lower the risk of neonatal sepsis.

Strategies To Boost Maternal Immunization To Achieve Further Gains In Improved Maternal And Newborn Health.

Despite the indisputable successes of the United Nations Millennium Development Goals, which include goals on improving maternal health and reducing child mortality, millions of mothers and newborns still die tragically and unnecessarily each year. Many of these deaths result from vaccine-preventable diseases, since obstacles such as cost and accessibility have hampered efforts to deliver efficacious vaccines to those most in need. Additionally, many vaccines given to mothers and children under age five are not suitable for newborns, since their maturing immune systems do not respond optimally during the first few months of life. Maternal immunization-the process by which a pregnant woman’s immune system is fortified against a particular disease and the protection is then transferred to her unborn child-has emerged as a strategy to prevent many unnecessary maternal and newborn deaths. We review vaccines that are already used for maternal immunization, analyze vaccines under development that could be used for maternal immunization strategies in the future, and recommend that policy makers use maternal immunization for improved maternal and newborn health.

Maternal and neonatal pneumococcal vaccination - where are we now?

Pneumococcus is a significant pathogen in neonates and in early infancy, particularly as a cause of invasive disease in sub-Saharan Africa where nasopharyngeal carriage rates are also exceptionally high. The pneumococcal-conjugate vaccines have now been rolled out in many high income settings and an increasing number of low and middle income countries. They have been highly effective at preventing vaccine serotype disease in infants. However, a window of susceptibility remains prior to the first vaccination at around six weeks of age. This paper summarizes the data available on both maternal and neonatal vaccination to prevent disease in newborns and early infancy and considers the key challenges and next steps for research in the field.