Despite widespread vaccine rollout, pertussis remains one of the least well-controlled vaccine preventable diseases worldwide, with a recent resurgence even in highly vaccinated populations. Although the exact underlying reasons are still not clear, emerging evidence suggests that a key factor is the replacement of whole-cell (wP) by acellular pertussis (aP) vaccines. Neither vaccine induces the same robust, long-lasting protection as natural infection, with aP-mediated immunity waning more rapidly than wP. Moreover, data from animal models suggest that aP vaccines fail to prevent upper airway colonisation and induce sterilising mucosal immunity, thereby facilitating transmission of Bordetella pertussis in settings with high vaccine coverage rates. There is no clear correlate-of-protection, but differences between pertussis vaccines are hypothesised to be cell-mediated, with polarisation of T-helper cell responses determined by infant vaccine composition. 

The title of my PhD project is 'Vaccine-induced systemic and mucosal immunity to Bordetella pertussis in infancy: bringing B- and T-cell responses together.' It is nested within a maternal/infant vaccine trial in The Gambia (Gambian Pertussis Study, GaPs, NCT03606096), capitalising on its unique design to provide a robust and in-depth characterisation of pertussis vaccine-induced T-helper cell immunity, and its contribution to long-term B-cell and antibody responses. These relationships will be evaluated in aP- compared to wP-vaccinated infants, using both blood and mucosal samples to understand the mechanisms underlying waning immunity and inadequate protection against infection/transmission. 

I hope that my findings will help to inform the design and testing of the next generation of more immunogenic and longer-lasting infant pertussis vaccines.

I am delighted to work with my supervisors Professor Beate Kampmann, Associate Professor Thushan de Silva, Dr. Sophie Roetynck as well as advisors and collaborators from MRC Unit The Gambia, Radboud University Medical Centre, Pertussis Correlates of Protection Europe (PERISCOPE) consortium and LSHTM.