Abstract
ABSTRACT Reduced antigen diphtheria-tetanus-acellular pertussis (Tdap) vaccination is included in the maternal immunization program in Brazil since September 2014. We investigated associations between maternal Tdap vaccination and pregnancy-related adverse events (AEs) (gestational diabetes, pregnancy-related hypertension, and pregnancy hemorrhage) and neonatal AEs of interest (preterm birth and small for gestational age). This descriptive, observational, retrospective, single-center study in Brazil (NCT02757950) compared data from medical charts of 1203 pregnant women who received Tdap as part of the maternal immunization program and delivered between May 2015 and February 2017 (exposed cohort) and 1259 unvaccinated women who delivered between September 2012 and August 2014 (unexposed cohort). Index dates were defined as the time of vaccination (27–39 gestational weeks; exposed cohort) or 27 gestational weeks (unexposed cohort). Cumulative incidences were calculated as the number of women with each event between index and delivery dates divided by the total number of women with vaccination date available in the exposed cohort (N = 1199) or the total number of women in the unexposed cohort (N = 1259). Cumulative incidences per 1000 persons were 8.34 versus 17.47 for gestational diabetes, 9.17 versus 24.62 for pregnancy-related hypertension, 3.34 versus 15.09 for pregnancy hemorrhage, 53.38 versus 96.11 for preterm birth, and 57.55 versus 49.25 for small for gestational age in the exposed versus unexposed cohorts. No increased risk of pregnancy-related AEs or neonatal AEs of interest was found following maternal vaccination with Tdap. These results should be interpreted cautiously due to limitations inherent to retrospective observational studies.
Highlights
Pertussis is a highly contagious severe respiratory infection caused by Bordetella pertussis[1]
We present the results of a retrospective study, which included 1203 vaccinated and 1259 unvaccinated pregnant women and was conducted in the immediate period after the introduction of Tdap in the maternal immunization program in Brazil
We found no association between vaccination with Tdap during the third trimester of pregnancy and the specific pregnancy-related adverse event (AE) or neonatal AEs of interest evaluated in this study
Summary
Pertussis is a highly contagious severe respiratory infection caused by Bordetella pertussis[1]. The risk of severe pertussis is higher in infants younger than 3 months of age due to their developing respiratory system and because they are too young to have completed their primary vaccination schedule against pertussis.[1] Outbreaks occurred in the last decade, underlining the need for effective protection against pertussis through vaccination. Overall pertussis incidence has increased in many countries since 2010, including several high-income countries with high coverage of acellular pertussis vaccination in childhood.[1,2,4,5,6,7,8] In Brazil, a systematic review of observational studies showed that pertussis disease incidence increased between 2010 and 2014, with an average incidence rate of 2.19 cases per 100 000 inhabitants and a peak of 4.03 cases per 100 000 inhabitants in 2014. A total of 415 deaths related to pertussis were recorded between 2010 and 2015 in Brazil, of which 97.6% occurred in children younger than 1 yof age.[9]
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