Expectant mothers who get a COVID-19 vaccine while pregnant pass immune protection on to their newborns, findings from the Centers for Disease Control and Prevention revealed Tuesday.
The chances that a baby 6 months old or younger is hospitalized due to COVID-19 are 61% lower if the mother received two shots of the Pfizer or Moderna vaccine while pregnant, the CDC’s Dr. Dana Meaney-Delman said.
Researchers studied newborns at 20 pediatric hospitals across 17 states from July 1, 2021 through Jan. 17.
The results showed that 84% of the babies hospitalized with COVID-19 had been born to unvaccinated mothers. The study included 43 infants admitted to an ICU with COVID-19, and found that 88% of them had mothers who did not get vaccinated before giving birth.
“The bottom line is that maternal vaccination is a really important way to help protect these young ones,” Meaney-Delman told reporters.
That’s especially important, she added, given that shots for this young cohort are still a ways off.
“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,” she said.
Vaccines for other illnesses have similarly been shown to safely cross the placenta and give newborns protection, including the shots for flu and whooping cough.
Previous research on COVID-19 vaccines had shown that pregnant mothers could pass antibodies to their babies, but the new study is the first to show real-world effects.
“These antibodies have been found in umbilical cord blood, indicating that the antibodies have transferred from the pregnant person to the developing infant,” Meaney-Delman said. “And while we know that these antibodies cross the placenta, until this study, we haven’t yet had data to demonstrate whether these antibodies might provide protection for the baby against COVID-19.”
The CDC study did not evaluate the effects of Johnson & Johnson’s vaccine on newborns, nor did it look at booster shots given during pregnancy.
But Dr. Manish Patel, the study’s lead author, said the agency hopes to gather and release data on boosters in the future.
“From all of the evidence on boosters increasing protection, antibody levels, we should see higher protection definitely and not lower protection with boosters,” Patel said.
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The data also seemed to indicate that babies born to mothers who were inoculated later in their pregnancies had even less risk of COVID-19 hospitalization than babes whose mothers got their shots early in pregnancy.
But Meaney-Delman said the CDC is not changing its recommendations to encourage any women to wait for a late-term vaccine or booster. Pregnant women face a higher risk of severe illness from a coronavirus infection, and recent research has shown that the virus can attack and destroy the placenta, leading to stillbirth.
As of Feb. 5, over 67% of pregnant people over age 18 had received at least two doses of the Pfizer or Moderna vaccine or one shot of Johnson & Johnson’s. That’s less than the share among the overall adult population: 74%.
People ages 5 and up in the U.S. are eligible for vaccination against the virus, which has killed more than 926,000 Americans. Among that eligible population, 68% of people are fully vaccinated, according to the CDC.
This story was originally published on NBCNews.com