Post-exposure booster vaccination recalls vaccine-induced memory and accelerates Bordetella pertussis clearance in murine lungs and trachea.

Despite high vaccination coverage, pertussis continues to cause substantial morbidity in infants, largely because acellular pertussis (aP) vaccines do not prevent bacterial carriage and transmission. Whether post-exposure booster vaccination can rapidly reduce respiratory carriage and thereby limit transmission remains unclear. We used an adoptive murine transfer model mimicking waning vaccine-induced antibodies observed in humans to assess the impact of post-exposure aP vaccination following respiratory challenge with Bordetella pertussis. Bacterial loads in the lungs and trachea and pertussis-specific antibody responses were assessed across multiple independent experiments. Post-exposure aP vaccination triggered a rapid recall of pertussis-specific antibodies and significantly accelerated bacterial clearance from both lungs and trachea. Compared with non-boosted immune mice, vaccinated animals showed significantly lower bacterial loads on days 7, 10, and 14 after exposure and cleared Bordetella pertussis earlier (p < 0.01). Similar reductions in bacterial burden were observed with delayed boosting, lower-antigen-content vaccines, and passive immunization. In this preclinical model, post-exposure pertussis booster vaccination efficiently recalls memory B cells and accelerates Bordetella pertussis clearance in the lung and upper airways. These findings support the potential role of post-exposure vaccination strategies as a complementary approach to limit transmission in household and community settings and thus better control epidemics.