Abstract:
Despite the availability of pertussis vaccines since the 1940s, pertussis epidemics still occur regularly, with significant consequences for families worldwide. Acellular pertussis (aP) vaccine effectiveness estimates vary by age, doses, local epidemiology, surveillance methods, and outcomes of interest. Understanding why aP vaccines fail and the factors predict failure may lead to better pertussis control in Aotearoa New Zealand (NZ).
Aim
To identify and test candidate predictors for pertussis vaccine failure in NZ.
Methods
This thesis comprises four data linkage studies investigating the epidemiology of pertussis vaccine failure in NZ between 2006 and 2016. Using individually linked data for almost all fully vaccinated infants and young children in NZ, the first study reported incidence and described pertussis vaccine failure cases. The second and third studies statistically tested host-related candidate predictors. The fourth study tested whether there were regional differences in susceptibility for pertussis vaccine failure during the 2011 – 2013 pertussis epidemic.
Findings
The incidence of pertussis vaccine failure over the study period was 0.3%. A small number of fully vaccinated pertussis cases were hospitalised, hospitalisations were not severe, and none died. The strongest signals for host-related candidate predictors were from those indicating respiratory vulnerability. Increased susceptibility to pertussis vaccine failure was observed in the region with the lowest pertussis vaccination coverage indicating some aP herd effect.