Chorioamnionitis following vaccination in the Vaccine Adverse Event Reporting System

Abstract

Background: In October 2012, the Advisory Committee on Immunization Practices (ACIP) recommended a dose of tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) during each pregnancy, irrespective of the patient’s prior history of receiving Tdap. A retrospective cohort study to assess the safety of Tdap vaccination in pregnant women in two Vaccine Safety Datalink (VSD) sites during 2010-2012 found a small but statistically significant increased risk of chorioamnionitis. Objective: We conducted a review of the VAERS database to describe reports of chorioamnionitis following receipt of any vaccines. Methods: We searched the VAERS database for reports of chorioamnionitis after any vaccine in the United States during the period from July 1, 1990 through February 2, 2014. Results: VAERS received 31 reports of chorioamnionitis out of 3,389 pregnancy reports. The three most common vaccines administered were 2009 H1N1 inactivated influenza, quadrivalent human papillomavirus (HPV4), and Tdap vaccines in 32%, 29% and 26% of reports, respectively. Fifty-eight percent of reports had at least one risk factor for chorioamnionitis. Chorioamnionitis was identified in 3 reports of spontaneous abortions and 6 stillbirths, 6 reports of preterm birth (two of whom died) and 16 reports of term birth; maternal outcomes included two reports of postpartum hemorrhage and one report of maternal admission to the intensive care unit. No maternal deaths were reported. Conclusion: Chorioamnionitis was found to be uncommonly reported, representing 1% of pregnancy reports to VAERS. A majority of reports had at least one risk factor for chorioamnionitis.

Safety of Maternal Immunization Against Pertussis: A Systematic Review

“…In contrast, other database analyses found no significant difference in chorioamnionitis between women who did and did not receive the Tdap vaccine during pregnancy [48,50,55], including those who received C 2 Tdap doses in the past 5 years [55]. An analysis of 31 chorioamnionitis cases among 3389 pregnancy reports in the Vaccine Adverse Event Reporting System (VAERS) database (between 1990 and 2014) identified that 58% of cases were in women with pre-existing risk factors [51]. Tdap (26%), H1N1 inactivated influenza vaccine (32%) and the quadrivalent human papillomavirus vaccine (29%) accounted for the majority of chorioamnionitis cases reported to the VAERS.…”

“…Twenty-one publications were identified that assessed maternal adverse events in women who received Tdap during pregnancy and pregnancy outcomes ( Table 1). Of these, 15 were database analyses [42][43][44][45][46][47][48][50][51][52][53][54][55][56][57]. Chorioamnionitis was identified as slightly increased in pregnant women who received Tdap (relative risk 1.19; 95% confidence interval [CI] 1.13-1.26) in a 2010-2012 retrospective, observational, cohort study using data from two Vaccine Safety Datalink sites [54].…”

Maternal death: Case definition and guidelines for data collection, analysis, and presentation of immunization safety data

“…A review of reports to the Vaccine Adverse event reporting system (VAERS) conducted by the CDC did not report any maternal deaths from 1990 to 2009 after the administration of the influenza trivalent inactivated or the live attenuated vaccine. Similarly, no maternal deaths were identified after immunization with Hepatitis A and B vaccine [12], meningococcal polysaccharide protein conjugate vaccine [18], tetanus toxide, reduced diptheria toxoid and acellular pertussis vaccine [19].…”

“…For more than one reasons, the temporal association of an AEFI may be more complicated in pregnancy than otherwise. For example, adverse events such as a mild inflammatory maternal response [11] and chorioamnionitis [12] have been demonstrated secondary to vaccination that have the potential to cause maternal morbidity and mortality. Also, a pregnant woman may suffer from obstetric complications such as hemorrhage, hypertensive disease of pregnancy, etc.…”

The safety of maternal immunization

“…47 A subsequent review of the VAERS system for all reports of chorioamnionitis showed that the condition is uncommonly reported following vaccination during pregnancy and 58% of women who report chorioamnionitis had at least one risk factor predisposing them to the condition. 49 The authors concluded chorioamnionitis was unlikely to be causally linked with pertussis vaccination during pregnancy.…”