COVID Vaccination during Pregnancy Protects Newborn Babies

COVID Vaccination during Pregnancy Protects Newborn Babies

By Shannon Hall

When Emily Kara was 34 weeks pregnant, she received an additional COVID vaccine. She did not technically qualify for one. She had received her latest dose merely five months earlier, and her midwife even advised against another shot. But Kara (who asked to go by her middle name out of concern for her privacy) was determined. She had read multiple studies that strongly suggested a maternal COVID vaccine would pass along antibodies to her baby girl and protect her after she was born, when she was vulnerable to SARS-CoV-2 (the virus that causes COVID) and too young to receive the vaccine herself.

So Kara received an extra shot. And she is incredibly thankful that she did. “It gives me peace of mind,” says Kara, whose baby is now nine months old and has not tested positive for COVID.

The first wave of COVID vaccine trials that began in 2020 excluded pregnant people—leaving expectant parents in the dark as to the vaccine’s safety for themselves and their child. But now that millions of pregnant people have received the vaccines, the data are solid. Not only do they show that the vaccines are safe and effective during pregnancy, but a growing consensus is also emerging that vaccinating a pregnant person against COVID can protect their newborn at a time when their little one’s immune system is not mature enough to mount its own defense. Some studies even suggest that the protection lasts until roughly six months of age, when infants are old enough to receive their own vaccine.

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The science is relatively simple: when a COVID vaccine is given during pregnancy, the parent’s immune system develops antibodies against a protein in SARS-CoV-2 that then cross the placenta to the fetus and thus protect the newborn. This is why pregnant people have long been advised to receive the flu shot and the Tdap (tetanus, diphtheria and pertussis) vaccine. And one vaccine—the respiratory syncytial virus (RSV) vaccine approved last year—was even developed specifically to be given during pregnancy to protect the baby after birth. “That is something that we really ought to be leveraging for COVID as well,” says David Kimberlin, a pediatric infectious disease specialist at the University of Alabama at Birmingham. “I think the data are clear.”

A study published in March in Pediatrics from the National Institute of Allergy and Infectious Diseases (NIAID) found that mothers who received an mRNA-based COVID vaccine during pregnancy protected their infant against symptomatic COVID infection for at least six months after birth. Last fall the U.S. Centers for Disease Control and Prevention similarly noted that infants born to women who had received a COVID vaccine—be it the primary series or a booster—at any point during pregnancy had a decreased risk of COVID hospitalization compared with infants who were born to women who had never received a COVID vaccine. And a study published in Nature Medicine in March 2023 found that newborns born to mothers who were vaccinated with a third (booster) dose were half as likely to be hospitalized for COVID as newborns born to mothers who had received the primary series and were eligible for a third dose during pregnancy but had not received it.

This protection is great news given COVID’s risk to newborn babies. “One of the facts that gets lost in the general public is that in the pediatric population, COVID is most severe among young infants, resulting in the highest rates of hospitalization and death in this young age group,” says Cristina Cardemil of the NIAID, who led the Pediatrics investigation. The hospitalization rate in babies under six months increased during the Omicron period and rivals that of adults aged 65-74. Not only have these infants never encountered these infectious diseases but they also have small airways and become dehydrated easily. “They’re doubly at risk for being vulnerable to a number of infectious diseases,” Cardemil says.

Now expectant parents have a tool to shield their baby. Multiple studies show similar findings, and many suggest that a COVID booster during the second or third trimester confers the best protection. The Nature Medicine study authors write: “We anticipate that future guidelines will adopt recommendations for routine COVID booster vaccination during the third trimester, aiming to reduce early infant morbidity, similar to recommendations for pertussis and influenza prevention.”

And yet that is not the case. The CDC currently recommends that everyone, pregnant people included, receive the most recent version of the COVID vaccine, but it does not recommend an additional booster to ensure vaccination during pregnancy or point toward a specific administration time. For example, a pregnant person could receive a COVID vaccine in the fall before conceiving and deliver a baby before the next fall vaccine is released—thus missing out on the benefits that an extra vaccine dose confers. The World Health Organization does recommend a single additional dose of the COVID vaccine during pregnancy, but this guideline seems to be the exception. In January, for example, Canada’s National Advisory Committee on Immunization provided guidance on who should get an additional spring booster, and pregnant people were not mentioned. The same was true for the U.K.’s spring booster campaign. (Guidelines from both countries note that the vaccine is safe and effective during pregnancy.)

The issue, experts say, is COVID fatigue. Governing agencies must make recommendations based on what is actually feasible, and an extra booster might be a hard sell when so few pregnant people are up to date on their COVID vaccine in the first place. In the U.S., for example, a mere 13 percent of pregnant people aged 18 to 49 have received the updated 2023–2024 COVID booster. “People are very lackadaisical about it,” says Laura Riley, chair of obstetrics and gynecology at Weill Cornell Medicine in New York City. “And I’m in a place where people get vaccinated.” So the CDC has streamlined the most important message: vaccination protects against disease.

In response to a request for comment, a spokesperson from the CDC said: “Available data show the vaccines for all eligible people—including pregnant people—continue to be strongly protective against severe illness and death.” For that reason, the agency recommends that pregnant people stay up to date on their vaccines, but it will continue to review available evidence on whether additional or differently timed doses might be needed.

Yet many experts argue that the recommendation does a disservice to pregnant people, who are at heightened risk from the disease, and their newborn. “The politicization of vaccines has led to this vaccine not being utilized as much as it should be,” says Sallie Permar, chair of pediatrics at Weill Cornell Medicine and pediatrician in chief at NewYork-Presbyterian Komansky Children’s Hospital. She argues that the COVID vaccine clearly falls into the same category as the flu and Tdap vaccines, whose “safety records and the benefits to both mom and baby have just been universally awesome.”

Kimberlin agrees and is hopeful that the tides will soon shift toward stronger recommendations and a higher vaccine uptake during pregnancy. “This is a very easy way to keep your baby safe,” he says. “And it absolutely should be recommended vigorously.”