The Pfizer and Moderna vaccines are both highly effective at producing antibodies against COVID-19 in pregnant women, according to a new study that delivers a bundle of good news to a vulnerable group that was excluded from trials for the experimental medicine.
The research, published in the American Journal of Obstetrics and Gynecology, also showed that protective immunity from the virus is passed to newborns through the placenta and breastmilk. “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, senior co-author of the study and a maternal-fetal medicine specialist at Massachusetts General Hospital.
“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.”
To arrive at their conclusions, researchers studied a group of 131 women — 84 pregnant, 31 lactating and 16 non-pregnant — who had been administered either the Pzifer/BioNTech or Moderna vaccines. Antibody levels were found to be equivalent across all three groups of women while side effects from the vaccination itself were rare and uniform among all participants. The researchers said they are optimistic their findings will encourage the recruitment of pregnant women for future trials.
“We now have clear evidence the COVID vaccines can induce immunity that will protect infants,” said Galit Alter, another co-senior author of the study and a core member of the Ragon Institute at Massachusetts General Hospital. “We hope this study will catalyze vaccine developers to recognize the importance of studying pregnant and lactating individuals, and include them in trials.
“The potential for rational vaccine design to drive improved outcomes for mothers and infants is limitless but developers must realize that pregnancy is a distinct immunological state, where two lives can be saved simultaneously with a powerful vaccine. We look forward to studying all vaccine platforms in pregnancy as they become available.”
Without the protection of a vaccine, the Center for Disease Control and Prevention said pregnant women are more likely to become severely ill from COVID-19 and require hospitalization or intensive care to overcome the virus — all factors that raise the risk of adverse outcomes for their unborn child. Researchers compared antibody levels in women who received a vaccine against those whose antibodies were a response to natural infection during pregnancy and found significantly higher levels among vaccine recipients. Antibodies produced by the vaccine were present in samples taken from umbilical cords and breastmilk.
Researchers also compared the different immune response generated by the two vaccines and discovered the second shot of Moderna resulted in higher levels of mucosal (IgA) antibodies than the second dose of Pfizer. “This finding is important for all individuals, since SARS-CoV-2 is acquired through mucosal surfaces like the nose, mouth and eyes,” said Kathryn Gray, a first author of the study and obstetrician at Brigham and Women’s Hospital at Harvard Medical School in Massachusetts. “But it also holds special importance for pregnant and lactating women because IgA is a key antibody present in breastmilk.”
Dave Yasvinski is a writer with Healthing.ca