Newborns appear to be protected from COVID-19 if their mothers are vaccinated, study finds

• CDC: Babies born to vaccinated moms are 61% less likely to be hospitalized with COVID-19.
• The report also found 84% of COVID-positive hospitalized infants had unvaccinated moms.

Moms who get vaccinated against COVID-19 pregnancy are less likely to have babies hospitalized with the illness in their first six months of life.

The findings, published Tuesday in the Center for Disease Control and Prevention's Morbidity and Mortality Weekly report, are the first to suggest, epidemiologically, that babies born to vaccinated mothers are protected against COVID-19.

Previously, experts only knew that vaccinated women seemed to pass antibodies against COVID-19 to their babies in utero, but they didn't know if that translated to real-world protection against the virus.

The new report bolsters doctors' recommendations to get the COVID-19 in pregnancy not just for the mom's health, but also for the baby.

"Today's news is highly welcome, particularly in the backdrop of the recent increase in hospitalizations among very young children. This has been the highest of the entire pandemic," Dr. Dana Meaney-Delman, an OB-GYN and chief of CDC's Infant Outcomes Monitoring Research and Prevention Branch, said during a press briefing.

"Unfortunately, vaccination of infants younger than 6 months old is not currently on the horizon, highlighting why vaccination during pregnancy is so important."

The COVID-positive babies needing the most intense care, including one who died, were born to unvaccinated moms

To conduct the study, researchers looked at data from infants hospitalized at 20 pediatric hospitals in 17 states between July 1, 2021 and January 17, 2022. They compared 176 babies who were hospitalized with COVID-19 to 203 who were hospitalized for other issues.

The study authors found that the newborns whose moms had been vaccinated with two doses of either Pfizer or Moderna's COVID-19 vaccine were 61% less likely to be hospitalized with COVID-19.

They also found that 84% of newborns hospitalized with COVID-19 had unvaccinated moms, and that 88% of the COVID-positive babies who were admitted to the ICU were born to unvaccinated women. The one baby who died was born to an unvaccinated mom.

All of the babies, no matter why they were hospitalized, had similar prevalences of underlying medical conditions. Those hospitalized with COVID-19 were more likely to be Black or Hispanic than those with other complications.

The researchers also found that babies seemed to be most protected if their moms were vaccinated later in pregnancy, but said to interpret that result with caution since the sample size was too small to look at risk by trimester. Plus, medical organizations and the CDC say the best time for moms-to-be to get the shot is now.

The study had some limitations, like that it didn't take into account whether moms had been infected with COVID-19. Women who are vaccinated may also have better access to prenatal care, which could have affected the results.

"I personally counsel all my pregnant patients that they are more likely to get severely ill, experience pregnancy complications, such as preterm delivery, even stillbirth, from COVID-19, and strongly encourage them to be vaccinated," Meaney-Delman said.

"They often ask me whether the vaccine protects the baby. This new study will undoubtedly factor in to my future counseling sessions."