Introduction:

Routine immunization of pregnant women with seasonal inactivated influenza vaccines (IIV) is recommended in all trimesters of pregnancy. A review of the Vaccine Adverse Event Reporting System (VAERS) during 1990–2009 did not find any unexpected patterns of pregnancy complications or fetal outcomes after administration of IIV or live attenuated influenza vaccines (LAIV). During 2009–2010 pandemic H1N1 vaccination campaign, a study noted that the numbers of VAERS reports from pregnant women who received the influenza A (H1N1) 2009 inactivated monovalent vaccine (N=288) increased compared to 1990–2009 seasonal IIV pregnancy reports (N=148).

Objectives:

To assess the safety of seasonal influenza vaccines in pregnant women and their infants whose reports were submitted to VAERS during 2010–2016.

Methods:

We searched VAERS for US reports of adverse events (AEs) in pregnant women who received IIV or LAIV from 7/1/2010–5/06/2016. Clinicians reviewed reports and available medical records and assigned a primary clinical category for each report. Reports were coded as serious, based on the Code of Federal Regulations.

Results:

We identified 671 reports after seasonal influenza vaccines administered to pregnant women: 544 after IIV and 127 after LAIV. Serious events occurred among 61 (11.2%) reports following IIV and 1 (0.8%) report following LAIV. No deaths were reported. Among reports with trimester information (n=296), IIV was administered during the first trimester in 116 (39.2%). Among IIV reports, the most frequent pregnancy-specific AE was spontaneous abortion in 62 (11.4%) reports, followed by stillbirth in 10 (1.8%) and preterm delivery in 6 (1.1%). The most common non-pregnancy specific AEs were injection site reactions (55, 10.1%). Neonatal or infant outcomes were reported in 22 (4.0%) reports, 7 of which had major birth defects of different types and no neonatal deaths.

Conclusion:

As in 2009–2010, no new or unexpected patterns in maternal or fetal outcomes were observed during 2010–2016.