Impact of vaccinating pregnant women against pertussis on hospitalizations of children under one year of age in a tertiary hospital in Catalonia.

INTRODUCTION

The recommendation for pertussis vaccination in pregnancy was established in Catalonia in February 2014. The objective of this study was to compare the hospitalisation rate for pertussis in children under one year of age before and after the implementation of the vaccination programme.

METHODS

Observational and retrospective study of patients under one year of age admitted to hospital with a diagnosis of pertussis. The hospitalisation rate of patients under one year of age of the period prior to the vaccination programme (2008-2013) was compared with the period with vaccination programme (2014-2019) in the total of children under one year of age and in 2 subgroups: children under 3 months and between 3-11 months.

RESULTS

Hospitalization rate was significantly lower in the period with vaccination programme in children under one year of age and specifically in children under 3 months (2.43 vs. 4.72 per 1000 person-years and 6.47 vs. 13.11 per 1000 person-years, respectively). The rate ratios were: 0.51 (95% CI 0.36-0.73) for children under one year of age; 0.49 (95% CI 0.32-0.75) for those younger than 3 months and 0.56 (95% CI 0.30-1.03) for those with 3-11 months. No statistically significant differences were observed in the clinical severity between both periods.

CONCLUSION

The introduction of the pertussis vaccination programme in pregnancy was associated with a global lower hospitalisation rate for pertussis in children under one year of age and specifically in those under 3 months of age.