February 16, 2022
Babies are far less likely to be hospitalized with COVID-19 if their mothers were vaccinated during pregnancy, a new study found.
Prior research had suggested a mother's antibodies from a COVID-19 vaccine transfer across the placenta to her unborn child. The new study offers real-world evidence that these antibodies offer the baby protection from the coronavirus.
Researchers from the U.S. Centers for Disease Control and Prevention found infants younger than 6 months were 61% less likely to be hospitalized with COVID-19 if their mothers received either the Pfizer or Moderna vaccines during pregnancy.
The level of protection was even higher when the expectant mothers were vaccinated between 21 weeks and 14 days before delivery. They were 80% less likely to be hospitalized.
"While we know that these antibodies cross the placenta, until this study, we have not yet had data to demonstrate whether these antibodies might provide protection for the baby against COVID-19," Dr. Dana Meaney-Delamn, head of the CDC's infant outcomes branch, said during a press conference Tuesday.
"Unfortunately, vaccination of infants younger than 6 months old is not currently on the horizon, highlighting why vaccination during pregnancy is so important for these young infants."
In the study, 84% of the infants hospitalized with COVID-19 were born to unvaccinated mothers. Of the babies who were not hospitalized, 68% were born to unvaccinated mothers.
Among babies with COVID-19 admitted to the ICU, 88% were born to mothers who were not vaccinated before or during pregnancy.
The CDC acknowledged some limitations to the study. It did not test mothers for COVID-19 before or during pregnancy and did not examine behavioral differences that also my have affected the babies' risk of infection.
The CDC recommends the COVID-19 vaccine for women who are pregnant, planning to get pregnant or breastfeeding. Data has shown that pregnant and recently pregnant women have a higher risk of severe COVID-19.
According to the CDC's COVID tracker, the vaccination rate among pregnant people is on the rise, but not where public health officials would like it to be. About 67% of pregnant people were vaccinated as of Feb. 5.
"I personally counsel all my pregnant patients that they are more likely to get severely ill and experience pregnancy complications, such as preterm delivery, or even stillbirth from COVID-19 and I strongly encourage them to be vaccinated," Meaney-Delamn said. "They often ask me whether the vaccine protects the baby and this new study will undoubtedly factor into my future counseling sessions."
The study was published in the CDC's Morbidity and Mortality Weekly Report. The study included 379 infants at 20 children's hospitals in 17 states from July through January. Of the 379 infants, 176 had COVID-19 and 203 did not.