The infants of mothers who completed two doses of either the Moderna or Pfizer/BioNTech coronavirus vaccines during pregnancy had a reduced risk for being hospitalized with Covid-19 in the first six months of their lives, a new study finds.
“The bottom line is that maternal vaccination is a really important way to help protect the young infants. Today’s news is highly welcome, particularly in the backdrop of the recent increase in hospitalizations among very young children,” Dr. Dana Meaney-Delman, chief of infant outcomes monitoring research and prevention branch at the US Centers for Disease Control and Prevention, told reporters during a news briefing Tuesday.
“Other diseases like flu and whooping cough, vaccination during pregnancy provides protection for infants during the first six months of their lives, a period when infants are at high risk for severe illness, but when they are not yet old enough to get vaccinated,” she added.
The study, published by the CDC on Tuesday, suggests that getting vaccinated during pregnancy might not only protect the mother against Covid-19, but her baby, too. And that protection appeared to be higher among infants whose mothers were vaccinated later in pregnancy.
“Further, with infants not currently age-eligible for vaccination and infant hospitalization rates remaining at the highest levels of the pandemic, this study suggests that maternal COVID-19 vaccination during pregnancy might protect infants” younger than 6 months from hospitalizations related to Covid-19, the researchers — from the CDC and other US institutions and universities — wrote in the new study.
The study included data on 379 hospitalized infants younger than 6 months — 176 with Covid-19 and 203 without Covid-19, but hospitalized for other reasons — at 20 pediatric hospitals in 17 states between July of last year and mid-January of this year. The mothers of the infants were asked about their Covid-19 vaccination history, including the number of doses completed and whether a dose had been received during pregnancy.
The report found that Covid-19 vaccination during pregnancy reduced the risk of infant hospitalization with Covid-19 by 61%. The effectiveness after completing vaccination early in pregnancy was 32%, and later in pregnancy was 80%.
“Most concerning, they found that among babies with Covid-19, who were admitted to the ICU, the sickest babies, 88% were born to mothers who were not vaccinated before or during pregnancy, and the one baby who died in the study was born to a mother who was not vaccinated,” Meaney-Delman said in Tuesday’s briefing.
The researchers found that overall, 15.9% of the mothers of infants with Covid-19 were vaccinated during pregnancy compared with 32% of the mothers of infants without Covid-19.
The data showed that 10.3% of the mothers of infants with Covid-19 had been vaccinated early during pregnancy and 5.7% were vaccinated in late pregnancy, compared with 15.9% of the infants without Covid-19 were vaccinated in early pregnancy and 21.6% in late pregnancy.
The researchers wrote that Covid-19 antibodies likely could be transferred across the placenta from a mother to the baby during pregnancy and “might provide protection to infants.”
“When people receive an mRNA Covid-19 vaccine during pregnancy, their bodies build antibodies to protect against Covid-19 and these antibodies have been found in umbilical cord blood, indicating that the antibodies had transferred from the pregnant person to the developing infant,” Meaney-Delman said.
The study did not include data on vaccine effectiveness of booster shots, or on mothers who were vaccinated before pregnancy.