COVID Vaccine During Pregnancy Protects Babies, Study Shows

A pregnant Asian female-presenting pregnant person receiving a vaccine from a white healthcare worker in blue scrubs at a vaccine clinic.


Key Takeaways

  • New data from the Centers for Disease Control and Prevention (CDC) has shown that when pregnant people were vaccinated against COVID-19, their babies younger than 6 months old were 61% less likely to be hospitalized with COVID.
  • It’s believed that antibodies from the vaccines are transferred across the placenta to the developing fetus.
  • The COVID protection that babies get lasts for 3 to 6 months after birth.

According to new data from the Centers for Disease Control and Prevention (CDC), people who got vaccinated against COVID-19 while they were pregnant are likely to pass protection on to their newborns.

The COVID vaccines have been shown to be safe and effective for pregnant people. The new data also provides reassurance to parents that their babies will also get the shots’ benefits.

Researchers looked at 379 infants under the age of 6 months in 17 states. Of the babies in the study, 176 had COVID and 203 did not have COVID.

The babies were seen at 20 different children’s hospitals in the United States from July 2021 to January 2022.

What the Data Showed

After analyzing the data, the researchers found that:

  • Infants younger than 6 months old whose pregnant parent got fully vaccinated with a two-dose COVID vaccine (Pfizer or Moderna) during pregnancy were 61% less likely to be hospitalized with COVID.
  • The protection appeared to be stronger if the parent got vaccinated after the first 20 weeks of pregnancy.

Did the Data Have Limitations?

One note is that the researchers did not take into consideration whether pregnant parents may have previously tested positive for COVID.

Kathleen Antony, MD, an associate professor of maternal-fetal medicine at the University of Wisconsin Hospital who was not involved in the research, told Verywell that how much risk an individual baby has depends on several factors—including exposure from parents, siblings, and their environment.

Overall, experts have commented that the data are not surprising, considering the growing body of research showing that vaccines are safe during pregnancy—and that they work.

How Is Immunity Passed?

Antony said that when a person gets vaccinated, their body naturally makes the proteins that the immune system needs to help fight infection (antibodies).

When a vaccine is given to a pregnant person, these antibodies can cross the placenta and get to the fetus.

“The placenta is the organ that the pregnant person’s blood goes through to get to the baby,” said Antony. “It allows some things to cross pretty freely like oxygen and certain nutrients.

According to Antony, the placenta “also allows certain antibodies to cross the baby and these antibodies can stay in the baby’s circulation after birth.”

Risks of Being Unvaccinated

There were also several key findings in the data that demonstrate the risks of being unvaccinated:

  • Of the 176 babies infected with COVID, 148 (84%) were born to people who had not been vaccinated during pregnancy.
  • 88% of the 43 babies who were admitted to an intensive care unit (ICU) with COVID were born to someone who was unvaccinated.
  • The one infant who died during the study and the one infant who required a heart-lung machine were both born to people who were unvaccinated.

Alan Fishman, MD, a maternal-fetal medicine specialist and the medical director for Obstetrix Medical Group of San Jose, told Verywell that “unvaccinated people are much more susceptible to infection and complications from COVID-19 than vaccinated people are.”

As a result, Fishman pointed out, “most of the hospitalizations for COVID-19 are in the unvaccinated.”

Alan Fishman, MD

Most of the hospitalizations for COVID-19 are in the unvaccinated.

— Alan Fishman, MD

According to Fishman, unvaccinated pregnant people “do not confer any protection to their developing babies and those infants are at a much higher risk of sickness.”

How Long Does Protection Last? 

The CDC data showed that the babies of people who were fully vaccinated while pregnant were less likely to be hospitalized for COVID in the first 6 months of life.

Antibodies from a COVID vaccine during pregnancy likely protect a newborn for about 3 to 6 months after birth.

Antony said that the antibodies that are passed from a pregnant person to a developing fetus do stay in the baby’s circulation after birth—but only temporarily.

“The antibodies start to decrease within the first few weeks to months of life depending on the type of antibody, how much was present, and whether there was a higher circulating amount of that antibody in the pregnant person’s blood or not,” said Antony. “Antibodies can last somewhere between a 3- to a 6-month window, but some can last up to 12 months.”

Fishman said that the protection falls over the course of 3–6 months because passive immunity wanes as the circulating antibodies that babies get from a pregnant parent are metabolized and slowly disappear. 

Research has shown that it is normal for virus-fighting antibodies, such as those that are produced by a COVID vaccine, to wane over time.

Vaccination Later in Pregnancy

The researchers found that protection from the vaccine was stronger when people received the shots later in pregnancy. The data showed that:

  • Babies born to people who were vaccinated from around 21 weeks up to 14 days before delivery were 80% less likely to be hospitalized with COVID.
  • On the other hand, babies born to people that received vaccines during the first 20 weeks of pregnancy were just 32% less likely to be hospitalized with COVID. 

Carlos Acuña-Villaorduña, MD, an infectious disease specialist at Boston University School of Medicine, told Verywell that based on existing studies, this finding could be attributed to vaccine-induced immunity decreasing over time. 

“Adults produce antibodies very well and then, indirectly, it will protect the baby,” said Acuña-Villaorduña. “But those antibodies can last in the fetus for only a few months when the baby is born. Protection can wane and go away after 6 months.”

The researchers also highlighted that it’s not yet clear when during pregnancy is the ideal time to get vaccinated.

If You’re Pregnant, Get Vaccinated

According to the CDC, the approved COVID vaccines are safe for pregnant people. They do not cause infertility or pregnancy complications.

However, data has also shown that when pregnant people get COVID, they are at an increased risk of severe complications and death.

Carlos Acuna-Villaorduña, MD

Vaccines are safe during pregnancy.

— Carlos Acuna-Villaorduña, MD

Babies, too, are at high risk if they get COVID. The researchers emphasized that infants younger than 6 months old may have “life-threatening complications from COVID-19, including acute respiratory failure.”

“Pregnant people are worried about COVID in their children—especially because we know that babies are immunologically vulnerable,” said Antony, adding that the new research is “just an excellent bonus and another good reason to get vaccinated.”

Getting vaccinated while you’re pregnant isn’t just about protecting yourself—it’s also the best thing that you can do to protect a child who is going to be born into a COVID world.

“Vaccines are safe during pregnancy,” said Acuña-Villaorduña. “Vaccines have not been associated with miscarriage events or unintended consequences.”

The CDC also recommends that you get vaccinated if you’re planning to get pregnant or are breastfeeding.

Other Ways to Protect Newborns

After getting vaccinated, Antony said that wearing masks, hand washing, socially distancing, and limiting exposure can help keep babies safe from COVID.

One of the most important steps a family can do to protect a new baby is also likely to be one of the harder ones to stick to. Antony said that restricting how many people are around a newborn is key to preventing them from being exposed to the virus.

“That’s obviously challenging,” said Antony. “But unfortunately, limiting the number of people in contact [with], handling, holding, and snuggling the baby can be helpful.”

What This Means For You

If you are pregnant or are thinking about becoming pregnant, experts recommend getting vaccinated against COVID-19 to protect yourself and your baby from severe illness.

The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit our coronavirus news page.

6 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Halasa NB, Olson SM, Staat MA, et al. Effectiveness of maternal vaccination with mRNA COVID-19 vaccine during pregnancy against COVID-19–associated hospitalization in infants aged <6 months — 17 states, July 2021–January 2022MMWR Morb Mortal Wkly Rep. 2022;71(7):264-270. doi:10.15585/mmwr.mm7107e3

  2. Centers for Disease Control and Prevention. Antibodies and COVID-19.

  3. Yale Medicine. COVID-19 boosters: the latest advice.

  4. Centers for Disease Control and Prevention. Planning for pregnancy.

  5. Stock SJ, Carruthers J, Calvert C, et al. SARS-CoV-2 infection and COVID-19 vaccination rates in pregnant women in ScotlandNat Med. Published online January 13, 2022. doi:10.1038/s41591-021-01666-2

  6. Centers for Disease Control and Prevention. Breastfeeding and caring for newborns if you have COVID-19.

By Alyssa Hui
Alyssa Hui is a St. Louis-based health and science news writer. She was the 2020 recipient of the Midwest Broadcast Journalists Association Jack Shelley Award.