Safety and protective effects of maternal influenza vaccination on pregnancy and birth outcomes: A prospective cohort study. (September 2020)

• Record Type: Journal Article
• Authors: Mohammed, Hassen; Roberts, Claire T.; Grzeskowiak, Luke E.; Giles, Lynne C.; Dekker, Gustaaf A.; Marshall, Helen S.
• Is Part Of: EClinicalMedicine. Volume 26(2020)
• Publication Date: 2020-09
• Subjects: Medicine -- Research -- Periodicals; Medical policy -- Periodicals; Clinical Medicine; Health Policy; Public Health; Medical policy; Medicine -- Research; Periodical; Electronic journals; Periodicals; 613
• DOI: 10.1016/j.eclinm.2020.100522
• Languages: English
• ISSNs: 2589-5370

Abstract

Abstract: Background: Our study aimed to assess the safety and protective effect of maternal influenza vaccination on pregnancy and birth outcomes. Methods: The study population comprised 1253 healthy nulliparous pregnant women in South Australia between 2015 and 2018. Participants were followed prospectively, with vaccination status (confirmed by medical records), pregnancy, and birth outcome data collected by midwives. Adjusted relative risks (aRRs) and adjusted hazard ratios (aHRs) were estimated accounting for time-varying vaccine exposure and temporal nature of each outcome. Findings: Maternal influenza vaccination (48%, 603 of 1253) reduced the risk for pre-delivery hospitalisation with influenza like illness (aHR 061; 95% CI 039, 097). Maternal influenza vaccination was not associated with spontaneous abortion (aHR 042, 95% CI 012, 145), chorioamnionitis (aRR 078, 95% CI, 032, 188), gestational hypertension (aHR 078, 95% CI 047, 129), pre-eclampsia (aHR 0.84, 95% CI 054, 127), gestational diabetes (aHR 116, 95% CI 082, 166) nor preterm birth (aHR 094, 95% CI 059, 149). No associations between antenatal influenza vaccination and congenital anomalies, admission to the neonatal care unit, low Apgar scores, and mechanical ventilation were observed. Results were not materially changed after adjustment for pertussis vaccination. We observed a protective effect of maternal influenza vaccination on low birth weight (aHR 046, 95% CI 023, 094) and a marginal protective effect on small for gestational age births (aHR 065, 95% CI 040, 104) during periods of high influenza activity. Interpretation: These results support the safety of maternal influenza vaccination and suggest a protective effect in reducing the rates of low birthweight and small for gestational age births. Funding: There was no funding for this study.