COVID-19 vaccination during pregnancy could protect against SARS-CoV-2 infection in infants

Co-author, Dr. Deshayne Fell helped conduct the register-based cohort study of all live-born infants in Norway born between Sept. 1, 2021 and Feb. 28, 2022. The study published in JAMA Internal Medicine is one of only two studies published that quantifies a reduction in COVID-19 infection risk in babies during the first four months of life if their mother was vaccinated during pregnancy.

"Young infants are at higher risk of severe COVID-19 compared with older children, and there is no approved COVID-19 vaccine for this age group. Getting fully vaccinated against COVID-19 during pregnancy helps protect young infants from potential SARS-CoV-2 infection when they are born," said Dr. Fell, Scientist at the CHEO Research Institute and Associate Professor in the University of Ottawa's Faculty of Medicine.

Of 21,643 newborns included in the study, 9,739 (45%) were born to women who received a second or third dose of a COVID-19 mRNA vaccine during the last two trimesters of pregnancy. Infants of mothers vaccinated during pregnancy had a lower incidence of confirmed SARS-CoV-2 infection compared with infants of unvaccinated mothers. The effectiveness of vaccination during pregnancy against infant infection was greater during the Delta variant-dominated period (before Jan. 1, 2022) compared with the Omicron period (starting Jan. 1, 2022).

"It is not unexpected that maternal COVID-19 vaccination during pregnancy could reduce infant infection, as similar protective benefits against infant infection have been observed for pertussis and influenza vaccination during pregnancy in randomized clinical trials and observational studies," said Dr. Fell, whose recent study published in JAMA found that receiving a COVID-19 vaccine during pregnancy does not lead to increases in the frequency of complications around the time of childbirth.

Pregnant women are recommended to receive COVID-19 vaccination to reduce their risk of severe COVID-19. This new study suggests that vaccination during pregnancy additionally provides protection to their newborns in the first few months after birth.