Effectiveness of maternal pertussis vaccination in protecting newborn: A matched case-control study
Pere Godoy, Manuel Garcìa Cenoz, Cristina Rius, Carmen Muñoz‐Almagro, Glòria Carmona, Miquel Alsedà, Mireia Jané, Maria-José Vidal, Raquel Rodríguez, Josep Álvarez, Neus Camps, Sofía Minguell, Mónica Carol, María Rosa Sala, Jesús Castilla, Ángela Domı́nguez
Abstract
INTRODUCTION: The objective was to estimate the effectiveness of maternal pertussis vaccination in protecting infants aged < 2 months. METHODS: We performed a case-control study. Laboratory-confirmed cases aged <8 weeks at disease onset were identified and 2-4 matched-controls born within ± 15 days of the case were included. Information was obtained from healthcare providers and maternal interviews. Odds ratios (OR) were calculated using multivariable conditional logistic regression. Vaccine effectiveness (VE) was estimated as (1 - OR) × 100%. RESULTS: 47 cases and 124 controls were studied. The mean age (in days) (39.8 ± 12.7 vs. 40.8 ± 13.2), weeks of gestation (38.8 vs. 39.1, p = 0.43) and mean birth weight (3.309 vs. 3.253 kg, p = 0.55) were comparable between cases and controls. Mothers of cases were less frequently vaccinated in the third trimester (59.6% vs. 83.9%, p <0.001). The VE of maternal vaccination in pregnancy was 88.0% (95%CI 53.8% -96.5%), and was slightly higher in those vaccinated before the 32nd week of gestation (88.5% vs 87.8%). CONCLUSION: Pertussis vaccination in pregnancy is very effective in reducing pertussis in children aged < 2 months. Vaccination before and after the 32nd week of pregnancy are equally effective in reducing the risk of pertussis.