Study Examines COVID-19 Vaccine Immunogenicity in Pregnant, Lactating Women

Results of a new study suggest that COVID-19 messenger RNA (mRNA) vaccines are immunogenic in pregnant and lactating women, including against viral variants.¹ 

It is known that pregnant women are at an increased risk of morbidity and mortality from COVID-19, but there is currently limited data on COVID-19 vaccine safety and efficacy in this population.

The study, which was published in JAMA, investigated the immunogenicity in 103 pregnant and lactating individuals aged 18 to 45 years who received either the Pfizer of Moderna COVID-19 vaccines. Overall, 30 pregnant, 16 lactating, and 57 neither pregnant nor lactating women who received a COVID-19 mRNA vaccine and 22 pregnant and 6 nonpregnant unvaccinated women with SARS-CoV-2 infection were enrolled in the study.¹ 

The investigators from Beth Israel Deaconess Medical Center (BIDMC) reported similar levels of vaccine-induced antibody function and T cell responses in all non-pregnant, pregnant, and lactating women after the second dose. Moreover, both pregnant and non-pregnant women who received the vaccines developed cross-reactive immune responses against the COVID-19 variants B.1.1.7 and B.1.351.^1,2

“The COVID-19 mRNA vaccines raised robust immune responses in pregnant, lactating, and non-pregnant non-lactating women,” said senior corresponding author, Dan H. Barouch, MD, PhD, director of the Center for Virology and Vaccine Research at BIDMC.² “Additionally, the vaccine-elicited antibody responses were greater than antibody responses seen after COVID-19 infections. These findings add to the emerging data that support the use of these vaccines in pregnant and lactating women.”

According to the further analysis, vaccination also elicited binding and neutralizing antibodies in breast milk, although immunoglobulin A responses were low in breast milk, with the exception of early breast milk from participants receiving the vaccine during pregnancy. Investigators also detected binding and neutralizing antibodies in infant cord blood, suggesting efficient transplacental transfer of maternal antibodies.¹ 

“The results of this study complement these studies by demonstrating neutralizing antibodies in both cord blood and breast milk, suggesting the possibility that newborns may be protected by maternal vaccination,” the investigators wrote.¹ 

References

1. Collier, AY. McMahan K, Yu J. Immunogenicity of COVID-19 mRNA vaccines in pregnant and lactating women. JAMA. Published online May 13, 2021. 10.1001/jama.2021.7563
2. COVID-19 mRNA Vaccines are Immunogenic in Pregnant and Lactating Women, Including Against Viral Variants. News Release. Beth Israel Deaconess Medical Center; May 13, 2021. Accessed May 14, 2021. https://www.bidmc.org/about-bidmc/news/2021/05/covid-19-mrna-vaccines-immunogenic-pregnant-lactating-women