Aims To assess whether preterm infants are at increased risk of pertussis infection and whether this increased following introduction of a maternal pertussis vaccination in England, while examining characteristics of infants associated with more severe disease.
Methods Infants aged <60 days admitted between 1 April 2009 and 31 March 2016 with a pertussis diagnosis code were extracted from Hospital Episode Statistics (HES) data. HES data were reconciled with existing surveillance systems to capture maternal vaccination status where available. Cases were compared preimplementation and postimplementation of the maternal programme with respect to demography, preterm or full-term birth and coinfection. Survival analysis was undertaken to assess the impact of variables on duration of hospital stay.
Results The proportion of hospitalised preterm infants (138/1309, 10.6%) was higher than population estimates (7.4%), increasing from 9.8% (83/847) to 12.1% (56/462) following implementation of the maternal programme. Longer duration of hospital stay was associated with prematurity, younger age, additional respiratory illnesses and mothers unvaccinated in pregnancy. Of 13 deaths, 5 were preterm (38.5%) and 11 (84.6%) were female. A larger proportion of full-term infants’ (49/188, 26.1%) mothers had been vaccinated in pregnancy than preterm infants (7/49, 14.3%), with 14.3% of mothers of full-term cases vaccinated after 35 weeks.
Conclusions Preterm infants are over-represented in hospitalised pertussis cases and have less benefit from the maternal pertussis vaccination programme in England due to reduced opportunity for maternal vaccination.
- maternal vaccination
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Contributors LB designed the study, extracted and managed HES data, conducted the analyses and interpretation of results, and drafted the manuscript. HC conceived the study and contributed to study design, interpretation of results and critical revision of the manuscript. NA provided statistical guidance with respect to the planning of the study, analysis and interpretation of the study data, and critically appraised the manuscript drafts. SR contributed to study design, extracted and managed enhanced surveillance data sets, collected data, and critically appraised the manuscript drafts. GA conceived the study and contributed to study design, interpretation of results and critical revision of the manuscript. All authors approved the final version of the manuscript.
Competing interests None declared.
Provenance and peer review Not commissioned; externally peer reviewed.
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