COVID-19 vaccination during pregnancy also protects babies
COVID-19 vaccination during pregnancy also protects babies

COVID-19 vaccination during pregnancy also protects babies

When mothers were vaccinated during pregnancy, the chances of their baby being admitted with severe COVID-19 decreased by 61 percent. (Images: Adobe Stock / Illustration: Patrick Bibbins, Boston Children’s Hospital)

Recent studies have shown that COVID-19 vaccination is safe for expectant mothers and can protect them from infection, serious illness and death from COVID-19. We also know that mothers who are vaccinated during pregnancy send coronavirus antibodies to their babies. Recent research – which draws on 20 children’s hospitals in 17 states – now confirms that vaccination of pregnant mothers protects their babies against severe COVID-19.

The ongoing Overcoming COVID-19 study, a national study conducted through Boston Children’s, identified 176 babies who were admitted due to COVID-19 and 203 babies who tested negative for COVID-19 and were admitted for other reasons. All infants were under 6 months of age and were hospitalized between July 2021 and January 2022.

The research team then interviewed infant families and checked vaccine records to determine mothers’ vaccination status. They considered mothers to have been vaccinated if they had received two doses of the Moderna or Pfizer BioNTech vaccine, with at least one of the doses given during pregnancy.

Overall, the study assessed that vaccination of pregnant mothers reduced the chances that their baby would be hospitalized with severe COVID-19 by 61 percent. The team also found out:

  • 84 percent of the infants admitted with COVID-19 were born to mothers who had not been vaccinated.
  • 88 percent of babies admitted to the intensive care unit (ICU) with COVID-19 were born to unvaccinated mothers.

To learn more, we sat down with Dr. Adrienne Randolph, a critical care physician at Boston Children’s. Dr. Randolph leads Overcoming COVID-19 and co-led the current study with researchers at the U.S. Centers for Disease Control and Prevention (CDC), which funded the study.

What is the most important thing about this study?

Infants are among the groups most at risk for complications from COVID-19. In this study, we showed that completion of COVID-19 vaccination during pregnancy was associated with a reduced risk of COVID-19 hospitalization in infants. We also showed that protection was higher when their mothers were vaccinated later in pregnancy. Vaccination not only protects mothers, it also helps protect the baby from getting COVID-19.

How sick were the babies who had COVID-19?

Many of them were seriously ill. Of the 176 infants admitted with COVID-19, 43 (24 percent) were admitted to the intensive care unit, and 25 babies (15 percent) needed life support during their hospital stay. One of these 25 infants died.

How did the timing of COVID-19 vaccination during pregnancy affect protection?

We compared infants of mothers who completed their second vaccine dose during the first 20 weeks of pregnancy versus the last 20 weeks (up to 14 days before birth). We need to study this more in a larger sample of infants, but it turned out that vaccination later in pregnancy protected the baby better. We estimated that it was 80 percent effective compared to 61 percent for the group as a whole.

But it is important to remember that vaccination also protects the mother. CDC, American College of Obstetricians and Gynecologists and Society for Maternal-Fetal Medicine recommend COVID-19 vaccination at any time during pregnancy. A healthy parent is important for a healthy baby.

What if I was vaccinated Before pregnancy?

When we started our study, mothers had just started getting vaccinated, so we did not have a large enough sample size to look at this. We are now doing this in a major study.

Did the study say anything about COVID-19 booster shots during pregnancy?

Our study started in July 2021, and booster shots only started to be given in late fall 2021. So we did not have enough mothers receiving boosters to answer this question, but we hope to do so when we have more data.

So the study on the effects of breastfeeding?

Again, we will have to study a larger group of infants to get a definitive answer. In our relatively small sample, babies without COVID-19 were more likely to be breastfed: 65 percent were breastfed compared to 55 percent of babies with COVID-19. We collect more data to better assess the potential protection of breastfeeding. But we know that mothers can transmit coronavirus antibodies to their babies through their breast milk.

Is this study continuing?

We are continuing this study and have now doubled the number of enrolled infants admitted with COVID-19. We plan to re-analyze the data soon. The larger sample size will give us more information about the time of vaccination during pregnancy and the protection of babies against COVID-19.

Learn more about COVID-19 research at Boston Children’s Hospital

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