This is a summary, written by members of the CITF Secretariat, of:

Jorgensen SCJ, Drover SSM, Fell DB, Austin PC, D’Souza R, Guttmann A, Buchan SA, Wilson SE, Nasreen S, Schwartz KL, Tadrous M, Wilson K, Kwong JC. Newborn and Early Infant Outcomes Following Maternal COVID-19 Vaccination During Pregnancy. JAMA Pediatr. 2023 Oct 23:e234499. doi: 10.1001/jamapediatrics.2023.4499.

The results and/or conclusions contained in the research do not necessarily reflect the views of all CITF members.

A CITF-funded study, published in JAMA Pediatrics, reported that maternal mRNA COVID-19 vaccination during pregnancy was associated with lower risks of severe neonatal morbidity, neonatal death, and neonatal intensive care unit (NICU) admission. Furthermore, there were no increases in neonatal admissions and readmissions by six months among infants of mothers vaccinated during pregnancy compared to infants of mothers who received no mRNA COVID-19 vaccine before delivery. CITF-funded researchers Drs. Deshayne Fell (Children’s Hospital of Eastern Ontario Research Institute, University of Ottawa), Jeffrey Kwong (ICES, University of Toronto), and Kumanan Wilson (University of Ottawa) contributed to the study.

Key findings:

  • Infants of vaccinated mothers had lower risks of severe neonatal disease (7.3% for infants of vaccinated mothers vs 8.3% for infants of unvaccinated mothers), neonatal death (0.09% of infants of vaccinated mothers died vs 0.16% of infants of non-vaccinated mothers), and NICU admission (11.4% of infants of vaccinated mothers vs 13.1% of infants of unvaccinated mothers).
  • There was no association between being vaccinated during pregnancy and having the baby readmitted to hospital soon after birth (5.5% among babies of vaccinated mothers vs 5.1% among babies of unvaccinated mothers) or over the six months after birth (8.4% among babies of vaccinated vs 8.1% among babies of unvaccinated mothers).
  • Compared with mothers in the unvaccinated group, those who were vaccinated during pregnancy were more likely to be older than 30 years, be nulliparousFemale who has never given birth to a live baby, have received influenza vaccine during either of the two previous influenza seasons, and be residents of urban areas and areas with higher incomes.

Overall, researchers highlighted that this study contributes to the scientific literature in two important ways. First, it provides further reassurance on the safety of maternal mRNA COVID-19 vaccination during all trimesters of pregnancy. Second, beyond confirming growing evidence of no apparent increased risks of adverse neonatal and early infant outcomes following maternal COVID-19 vaccination during pregnancy, this study demonstrates the benefits to infants with lower risks of severe neonatal morbidity, neonatal death, and NICU admission.

The study included 142,006 infants (72,595 male or 51%) and the mean gestational age at birth was 38.7 weeks. 85,670 infants were exposed to 1 or more COVID vaccine doses in utero (60%), with 41,621 mothers receiving 1 dose (48.6%), 42,523 receiving 2 doses (49.6%), and 1,526 receiving 3 doses during pregnancy (1.8%). Overall, 27,960 received 1 or more dose(s) in the first trimester, 45,901 received 1 or more dose(s) in the second trimester (33%), and 38,410 received 1 or more dose(s) in the third trimester (45%). A total of 58,533 women received Pfizer BNT162b2 for all doses during pregnancy (68%).

This population-based retrospective cohort study took place in Ontario, using multiple linked health administrative databases. Singleton live births with an expected delivery date between May 1, 2021, and September 2, 2022, were included. Data were analyzed from January 2023 through March 2023.