Antenatal pertussis vaccine effectiveness in England remains high post COVID-19

In 2024, pertussis peaked at nearly 15,000 confirmed cases in England leading to the declaration of a national public health incident. Infants aged under 3 months had the highest incidence, with eleven deaths in 2024. The maternal programme effectiveness was reassessed as eligibility had been extended to 16 weeks since earlier estimates.

188 laboratory-confirmed cases in under 3-month-olds from January 2020-March 2024, and matched coverage data from 453,740 pregnancies in the Clinical Practice Research Datalink, were used to estimate maternal vaccine effectiveness (VE) using the screening method. Cases were matched to coverage by birth-month, maternal age and region. VE was estimated against disease, hospitalisation and death.

VE against laboratory-confirmed pertussis was 84.6% (95% CI 76.9%-89.7%) in infants under 3 months. VE against hospitalisation was 88.2% (95% CI 81%-92.7%) with VE against death at 91.5% (95% CI 75.4%-97.1%). VE estimates for each gestational age category were high, with no statistically significant differences.

High maternal VE was estimated for infant pertussis regardless of the gestational age at vaccination. Resultscomparable to earlier estimates, indicate that the high effectiveness of the programme has been maintained and was not a factor in the post-pandemic pertussis resurgence observed in England, and internationally.