Researchers at Massachusetts General Hospital, Brigham and Women’s Hospital, and the Ragon Institute of MGH, MIT, and Harvard found that the Covid-19 mRNA vaccines could be highly effective in pregnant women and lactating mothers.
The researchers carried out the largest of its kind study to demonstrate that the vaccines also offer protective immunity to newborns through breastmilk and the placenta.
The study, published in the American Journal of Obstetrics and Gynecology (AJOG), analysed 131 women of reproductive age (84 pregnant, 31 lactating, and 16 non-pregnant). All the participants received one of the two new mRNA vaccines: Pfizer/BioNTech or Moderna.
The vaccine-induced titers - or antibody levels - were equivalent in all three groups. The researchers also noted that the side effects after vaccination were rare and comparable across the study participants.
“This news of excellent vaccine efficacy is very encouraging for pregnant and breastfeeding women, who were left out of the initial Covid-19 vaccine trials,” said Andrea Edlow, MD, MSc, a maternal-fetal medicine specialist at MGH, Director of the Edlow Lab in the Vincent Center for Reproductive Biology and co-senior author of the new study.
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Edlow added: “Filling in the information gaps with real data is key - especially for our pregnant patients who are at greater risk for complications from Covid-19. This study also highlights how eager pregnant and lactating individuals are to participate in research.”
According to the Centers for Disease Control and Prevention, pregnant individuals are more likely to become severely ill with Covid-19. They may require hospitalisation, intensive care, or ventilation - and may be at increased risk for adverse pregnancy outcomes.
The team also compared vaccination-induced antibody levels to those induced by natural infection with Covid-19 in pregnancy. The researchers found significantly higher levels of antibodies from vaccination.
Vaccine-generated antibodies were also present in all umbilical cord blood and breastmilk samples taken from the study, showing the transfer of antibodies from mothers to newborns, the researchers noted.