Pregnant and Breastfeeding Women Benefit from mRNA COVID-19 Vaccination

In an exploratory analysis published by The Lancet on May 13, 2021, receipt of a COVID-19 mRNA vaccine was found immunogenic in pregnant women.

Additionally, COVID-19 vaccine-elicited antibodies were transported to infant cord blood and breast milk.

These pregnant and nonpregnant women who received either the U.S. FDA Authorized mRNA-1273 (Moderna) or BNT162b2 (Pfizer-BioNTech) COVID-19 vaccines developed cross-reactive antibody responses and T-cell responses against SARS-CoV-2 variants of concern.

This study enrolled 103 women aged 18 to 45 years (66% non-Hispanic White) who received a COVID-19 mRNA vaccine. After the second vaccine dose, fever was reported in 4 pregnant women (14%; SD, 6%), 7 lactating women (44%; SD, 12%), and 27 nonpregnant women (52%; SD, 7%). Binding, neutralizing, and functional non-neutralizing antibody responses and CD4 and CD8 T-cell responses were present in pregnant, lactating, and nonpregnant women following vaccination.

Binding and neutralizing antibodies were also observed in infant cord blood and breast milk. Binding and neutralizing antibody titers against the SARS-CoV-2 B.1.1.7 and B.1.351 variants of concern were reduced, but T-cell responses were preserved against viral variants.

This study was funded by grant CA260476 from the National Institutes of Health (NIH), and grants from the Ragon Institute of Massachusetts General Hospital, Massachusetts Institute of Technology, Harvard, the Massachusetts Consortium for Pathogen Readiness, and the Musk Foundation (DHB); AI146779 from the NIH (AGS); HD000849 from the Reproductive Scientist Development Program from the Eunice Kennedy Shriver National Institute of Child Health & Human Development and Burroughs Wellcome Fund (AYC), AI007387 from the Multidisciplinary AIDS Training Program (LHT), and TR002541 from the Harvard Clinical and Translational Science Center (MRH).

The funders had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.