Infants whose mothers received two doses of mRNA coronavirus vaccine during pregnancy are less likely to be hospitalized for Covid-19 in the first six months of life, according to a new study from the Centers for Disease Control and Prevention. Overall, maternal vaccination was 61 percent effective in preventing infants from being hospitalized, the researchers found.
Vaccination later in pregnancy – after the first 20 weeks – appeared to protect infants better than vaccination earlier, the study found.
The new study is the first real-world epidemiological evidence that maternal vaccination can protect infants from Covid-19, likely because they are born with their mother’s antibodies.
“The bottom line is that maternal vaccination is a really important way to protect these young infants,” said Dr. Dana Meaney-Delman, director of the CDC’s Infant Outcomes Research and Prevention Division, at a news conference Tuesday.
The CDC recommends that women who are pregnant, breastfeeding, or trying to conceive get vaccinated against Covid-19, which can be dangerous for pregnant women and their children. For example, research has shown that the disease can increase the risk of a variety of pregnancy complications, including preterm birth and stillbirth.
Previous research on other diseases has shown that women who are vaccinated against other pathogens during pregnancy can pass antibodies across the placenta to the fetus, and scientists have previously found evidence that the same antibody transmission occurs after vaccination against Covid-19 could take place.
The new study focused on children under the age of six months admitted to one of 20 US children’s hospitals between July 1 and January 17. Of the 379 infants included in the study, 176 had been admitted for Covid-19 or had symptoms of the disease; All of these children tested positive for the virus. The remaining 203 children tested negative for the virus.
Among infants with Covid-19, 16 percent of mothers had been vaccinated during pregnancy, compared with 32 percent of mothers of hospitalized children without the virus.
Vaccination during the first 20 weeks of pregnancy was 32 percent effective against Covid-19-related infant hospitalizations, the researchers found, while later vaccination was 80 percent effective.
However, due to the relatively small sample size, more research is needed to determine the optimal timing of vaccination during pregnancy and whether booster vaccination during pregnancy might provide similar protection for infants whose mothers have already received their first vaccinations.
“Right now we want to make sure we’re protecting both the mother and the baby, and as soon as a pregnant woman is ready to get vaccinated, we encourage her to do so,” says Dr. called Meaney-Delman.
She added: “Unfortunately, vaccination of infants under the age of six months is not on the horizon at this time.”
The study was also not large enough to determine whether the maternal vaccine was equally protective against Delta, which was the dominant variant at the start of the study, and Omicron, which had supplanted Delta by the time the research ended.