Efficacy and Clinical Outcomes of mRNA COVID-19 Vaccine in Pregnancy: A Systematic Review and Meta-Analysis

The world has witnessed one of the largest pandemics, dubbed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). As of December 2020, the USA alone reported 98,948 cases of coronavirus disease 2019 (COVID-19) infection during pregnancy, with 109 related maternal deaths. Current evidence suggests that unvaccinated pregnant women infected with SARS-CoV-2 are at a higher risk of experiencing complications related to COVID-19 compared to nonpregnant women. This review aimed to provide healthcare workers and non-healthcare workers with a comprehensive overview of the available information regarding the efficacy of vaccines in pregnant women.

We performed a systematic review and meta-analysis following PRISMA guidelines. The search through the database for articles published between December 2019 and October 2021 was performed. A comprehensive search was performed in PubMed, Scopus, and EMBASE databases for research publications published between December 2019 and October 2021. We focused on original research, case reports, case series, and vaccination side effect by authoritative health institutions. Phrases used for the Medical Subject Heading [MeSH] search included ("COVID-19" [MeSH]) or ("Vaccine" [MeSH]) and ("mRNA" [MeSH]) and ("Pregnant" [MeSH]). Eleven studies were selected and included, with a total of 46,264 pregnancies that were vaccinated with mRNA-containing lipid nanoparticle vaccine from Pfizer/BioNTech and Moderna during pregnancy. There were no randomized trials, and all studies were observational (prospective, retrospective, and cross-sectional). The mean maternal age was 32.2 years, and 98.7% of pregnant women received the Pfizer COVID-19 vaccination. The local and systemic adverse effects of the vaccination in pregnant women were analyzed and reported. The local adverse effects of the vaccination (at least 1 dose) such as local pain, swelling, and redness were reported in 32%, 5%, and 1%, respectively. The systemic adverse effects such as fatigue, headaches, new onset or worsening of muscle pain, chills, fever, and joint pains were also reported in 25%, 19%, 18%, 12%, 11%, and 8%, respectively. The average birthweight was 3,452 g. Among these pregnancies, 0.03% were stillbirth and 3.68% preterm (<37 weeks) births.

The systemic side effect profile after administering the COVID-19 mRNA vaccine to pregnant women was similar to that in nonpregnant women. Maternal and fetal morbidity and mortality were lowered with the administration of either one or both the doses of the mRNA COVID-19 vaccination.