Sustained Effectiveness of the Maternal Pertussis Immunization Program in England 3 Years Following Introduction

Abstract

The effectiveness of maternal immunization in preventing infant pertussis was first demonstrated in England, 1 year after the program using diphtheria-tetanus-5-component acellular pertussis-inactivated polio vaccine (dT5aP-IPV) was introduced in 2012. Vaccine effectiveness against laboratory-confirmed pertussis has been sustained >90% in the 3 years following its introduction, despite changing to another acellular vaccine with different antigen composition. Consistent with this, disease incidence in infants <3 months of age has remained low despite high activity persisting in those aged 1 year and older. Vaccine effectiveness against infant deaths was estimated at 95% (95% confidence interval, 79%-100%). Additional protection from maternal immunization is retained in infants who received their first dose of the primary series. There is no longer evidence of additional protection from maternal vaccination after the third infant dose. Although numbers are small and ongoing assessment is required, there is no evidence of increased risk of disease after primary immunization in infants whose mothers received maternal vaccination.

Keywords: maternal pertussis vaccination; vaccine effectiveness.

Figure 1.

Maternal pertussis vaccine coverage, England, October 2012–August 2013, Clinical Practice Research Datalink (CPRD) and Immform. Denominator for CPRD is number of women delivering a live infant, by week of birth; denominator for Immform is number of pregnant women with an estimated date of delivery, each month. Abbreviations: dT3aP, diphtheria–tetanus–3-component acellular pertussis vaccine; dT5aP, diphtheria–tetanus–5-component acellular pertussis vaccine; IPV, inactivated polio vaccine.

Figure 2.

Incidence of laboratory-confirmed pertussis, by year and age group, England only, 1998–2015.