Vaccination During Pregnancy Passes Antibodies to the Baby

By now, you probably know that everyone—especially pregnant women—needs to be vaccinated against the virus that causes COVID-19. There is almost no medical reason not to get the vaccine even if you are pregnant. And now there is a really good reason to be vaccinated during pregnancy.

Researchers at the New York University Grossman School of Medicine found that every one of 36 newborn babies whose mothers had been vaccinated against the virus that causes COVID-19 had received antibodies that will protect them as well. These antibodies should protect these babies from becoming severely ill with COVID-19 for at least the first few months of their lives.

In other words, the immunity that vaccines provide to the mother has transferred to the baby.

Antibodies are proteins in the blood that are made by the immune system to fight off infections. They can be formed by the body in response to an infection but getting vaccinated triggers the body to form antibodies so that it is protected from serous infection.

The tests were done on samples taken at birth of cord blood, which is from the umbilical cord. Antibodies found in the cord blood were the same type of antibodies that are created in response to the vaccines. They were not antibodies that would have been the result of the mother having a COVID-19 infection. This is important because antibodies made by the body in response to a COVID-19 infection are not as protective for many people as the antibodies formed in response to a vaccine.

The study found that the highest levels of antibodies were found in samples of cord blood from mothers who had been vaccinated in the second half of their pregnancies. One mother in the study had only received one dose of vaccine before giving birth, but her cord blood also had antibodies.

The research team was led by Ashley Roman, MD, Professor of Obstetrics and Gynecology, and Jennifer Lighter, MD, an Associate Professor of Pediatrics at NYU Grossman.

“Studies continue to reinforce the importance of vaccines during pregnancy and their power to protect two lives at once by preventing severe illness in both mothers and babies,” said Dr. Roman in a statement from NYU. “If babies could be born with antibodies, it could protect them in the first several months of their lives, when they are most vulnerable.”

“Our findings add to a growing list of important reasons why women should be advised to receive the COVID-19 vaccine during pregnancy for the added benefit of their newborn receiving crucial protection,” added Dr. Lighter.

The mothers had received either the Pfizer or Moderna vaccine, both of which use messenger RNA. The same research team at NYU also studied the safety of vaccination against COVID-19 during pregnancy. That study found that there were no increased risks during the pregnancy or birth, or to the baby.

Being vaccinated against COVID-19 is incredibly important because pregnant women are at an increased risk for becoming sick from the virus. The Centers for Disease Control and Prevention strongly recommends that pregnant women get both shots of either the Pfizer or Moderna COVID-19 vaccine or one shot of the Johnson& Johnson COVID-19 vaccine. Studies have not found an increased risk of miscarriage in pregnant women who received the vaccines. Despite this, only about 23% of pregnant women get vaccinated against the virus.

The study is small, with only 36 samples of cord blood being evaluated. But the findings agree with other studies that show that most vaccines administered during pregnancy will provide antibodies to the baby. “It is consistent with what we see with other immunizations,” said Dr. Lighter.

More research is needed to find out how long the antibodies last in the babies and how effective the protection is.

The study on antibodies in the babies was published in the September 22 issue of the American Journal of Obstetrics & Gynecology—Maternal-Fetal Medicine and can be found on their website. The study by the same research group of the safety of COVID-19 vaccination appeared in the August 16 issue of the same journal and can also be found online.

Valerie DeBenedette
Valerie DeBenedette is an experienced health and medical writer who lives about an hour north of New York City with a dog that is smaller than her cat. Her work has appeared in magazines, newspapers, newsletters, and on websites. She is a member of the National Association of Science Writers.

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