The Pfizer/BioNTech and Moderna COVID-19 vaccines are safe and highly effective in producing antibodies against the SARS-CoV-2 virus during pregnancy, according to a new study. It also looks like some of the protective antibodies can be passed to fetuses through the placenta and to newborns through breast milk.
In the largest study on the vaccines and pregnancy to date, scientists at Harvard, MIT, Massachusetts General Hospital (MGH), Brigham and Women's Hospital, and the Ragon Institute of MGH, MIT, and Harvard report their findings in the American Journal of Obstetrics and Gynecology. They looked at 131 women in the US who received either the Pfizer/BioNTech or Moderna COVID-19 vaccine, of whom 84 were pregnant, 31 were lactating, and 16 were not pregnant.
Although it's a very small group, it’s very promising news. Equal levels of vaccine-induced antibodies against COVID-19 were found in pregnant women and lactating women, compared to non-pregnant women. Vaccine-generated antibodies were present in all umbilical cord blood, indicating they were being passed to the fetus, and breastmilk samples, indicating they were being passed to breastfeeding babies.
The data also showed no significant differences in post-vaccination reactions in pregnant versus non-pregnant women, implying the vaccines are safe to receive during pregnancy.
Pregnant and lactating women were not included in the initial COVID-19 vaccine trials, meaning there was no hard data on whether it was safe or effective. Considering individuals who are pregnant are at a heightened risk of COVID-19, there was also a real need to see whether the vaccine was still effective.
This limited evidence also sparked misinformation on social media, with some falsely claiming the mRNA COVID-19 vaccines could cause problems with fertility and impact pregnancy. These ideas were never seriously entertained by scientists, but it did spread some understandable concern among people looking to start families in the near future. This new study should allay some of those fears.
“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,” Andrea Edlow, co-senior author of the new study, Maternal-Fetal Medicine specialist at MGH, and director of the Edlow Lab in the Vincent Center for Reproductive Biology, said in a statement.
“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.”
Currently, the US Centers for Disease Control and Prevention (CDC) advises that the question of whether pregnant individuals should get the COVID-19 vaccine is a matter of “personal choice.” While they concede there is currently limited data on the safety of COVID-19 vaccines in pregnant people, they note “experts believe they are unlikely to pose a specific risk for people who are pregnant.”
The UK government has been more cautious, issuing the advice: “The vaccines have not yet been tested in pregnancy, so until more information is available, those who are pregnant should not routinely have this vaccine.”
Thankfully, this vital information is now starting to come to light. The CDC is currently recruiting people to join the v-safe pregnancy registry to gather information on the health of pregnant people who have received a COVID-19 vaccine.