Safety Monitoring of Bivalent Mrna Covid-19 Vaccine Among Pregnant Persons in the Vaccine Adverse Event Reporting System – United States, September 1, 2022 – March 31, 2023

Background: Pregnant persons are at increased risk of severe COVID-19 illness. Bivalent mRNA COVID-19 vaccination is recommended for everyone, including pregnant persons. However, data are limited on the safety of bivalent mRNA COVID-19 vaccination during pregnancy. Objective: To evaluate and summarize reports to the Vaccine Adverse Event Reporting System (VAERS), a national spontaneous reporting system, among pregnant persons who received bivalent mRNA COVID-19 vaccine. Methods: We searched VAERS for U.S. reports of adverse events (AEs) in pregnant persons who received bivalent mRNA COVID-19 vaccine from 9/1/2022-03/31/2023. Clinicians reviewed all reports and available medical records. We compared AEs of these reports with monovalent mRNA COVID-19 booster vaccination in pregnancy. Results: VAERS received 136 reports for pregnant persons who received bivalent mRNA COVID-19 vaccine; 87 (64%) after BNT162b2 (Pfizer-BioNTech), and 48 (35%) after mRNA-1273 (Moderna); 28 (20.6%) reports were classified as serious. The most common pregnancy-specific outcomes reported included 12 (8.8%) spontaneous abortions (<20 weeks gestation), 6 (4.4%) episodes of preterm delivery, and 5 (3.7%) reports of preeclampsia. One stillbirth (≥20 weeks gestation) was reported. No maternal or infant deaths were reported. There were 6 reports of AEs in infants, which included 3 reports of admissions to the neonatal intensive care unit: two infants with low birth weight, and one infant with a patent ductus arteriosus and patent foramen ovale. Non-pregnancy-specific adverse events were mostly COVID-19 infection and systemic reactions (e.g., headache, fatigue). Pregnancy-specific conditions were reported less frequently after bivalent mRNA COVID-19 vaccination compared to monovalent mRNA COVID-19 booster vaccination (3rd and 4th dose). Conclusions: Based on this review of reports to VAERS, the safety profile of bivalent mRNA COVID-19 vaccination in pregnant persons was comparable to that observed for monovalent mRNA COVID-19 booster vaccination (3rd and 4th dose) in pregnant persons.