Alliance for Pandemic Preparedness

April 29, 2021

Antibody Response to Coronavirus Disease 2019 (COVID-19) Messenger RNA Vaccination in Pregnant Women and Transplacental Passage Into Cord Blood

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  • Among 122 pregnant women who delivered on or after 35 weeks gestation and received a COVID-19 mRNA vaccine by the time of delivery (n= 55 first dose, n=67 both doses), anti-SARS-CoV-2 IgG antibodies were detected in maternal blood as early as 5 days and in cord blood as early as 16 days after the first dose. An IgG response was detected in 106 women at birth, of whom 19 also produced an IgM response. In contrast, antibody responses were not detected among 16 women who were within 4 weeks of the first vaccine dose. 44% (24 of 45) of cord blood samples from single dose recipients had detectable IgG compared to 99% (65 of 67) of samples from fully vaccinated women. Maternal IgG levels were linearly associated with cord blood IgG levels and placental transfer ratios correlated with the number of weeks since receipt of the second dose. The authors state these findings suggest timing between vaccination and birth may be important to consider for vaccination strategies for pregnant women.

Prabhu et al. (Apr 28, 2021). Antibody Response to Coronavirus Disease 2019 (COVID-19) Messenger RNA Vaccination in Pregnant Women and Transplacental Passage Into Cord Blood. Obstetrics & Gynecology. https://doi.org/10.1097/AOG.0000000000004438