COVID-19 Antibodies Can Be Passed To Babies In Utero

by Virginia Duan
African American female doctor preparing a pregnant woman for vaccination. Pregnant woman getting a ...
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As if the pandemic was not scary enough, add a little bit of pregnancy on top of it and the pandemic instantly gets even more terrifying. Not only are you worried about catching the coronavirus, you also worry about how the virus affects your developing fetus. While there is some data on how the coronavirus affects pregnant women and their babies, so much is still yet unknown. Now that there are several COVID vaccines, people are also concerned about their safety for expectant or breastfeeding mothers..

Because pregnant people are more vulnerable to certain infections due to changes in immunity and body systems in addition to the possibility of passing the infection onto their baby, scientists are understandably curious about how COVID-19 will affect both expectant mother and the fetus. Will the baby be born with COVID-19 or pass along antibodies and confer some protection?

Pregnant women can pass COVID antibodies to their babies

There are now several recently published studies and new findings that suggest expectant mothers can pass COVID antibodies to their babies in utero. This is important because the immune system of newborns doesn’t kick in until about 2 to 3 months and is reliant on any antibodies the mother passes along across the placenta or through breastfeeding (which is why vaccinations for infants are so vital to their health).

In a study published in January 2021, 67% of newborns delivered by women with COVID-19 antibodies also had COVID-19 antibodies in their system. The purpose of the study was to determine if being infected with the coronavirus caused complications in the birthing process — it doesn’t — as well as to determine the frequency of COVID-19 antibodies in the populations of pregnant women, their partners, and their babies.

In another study of 1,470 women conducted between April 9, 2020 and August 8, 2020 at the Pennsylvania Hospital in Philadelphia, researchers found that COVID-19 antibodies crossed the blood-placental barrier in 72 of the 83 pregnant women who tested positive for antibodies. Furthermore, according to one of the study’s senior authors Scott E. Hensley, it seemed to suggest that if women were infected earlier in their pregnancy, they transferred more antibodies to their babies.

Dr. Hensley, professor of microbiology at the Perelman School of Medicine at the University of Pennsylvania, told the New York Times that this finding could inform the timing of vaccinating pregnant women against COVID-19. Though the study could suggest that COVID vaccinations earlier in pregnancy would provide more protection to the baby, Dr. Hensley cautioned, “Studies actually analyzing vaccination among pregnant women need to be completed.”

What does the presence of COVID antibodies in newborns mean?

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So, what does the presence of COVID antibodies in babies born of people testing positive for COVID antibodies tell us?

First, a quick refresher on how antibodies work. When your body is exposed to a virus or pathogen, your white blood cells will make antibodies specifically tailored to that invader. The next time your body encounters that unique virus, your immune system will recognize and attack it.

In the case of COVID-19, it may take 1 to 3 weeks after exposure before you may make antibodies — and even then, some people don’t ever make any. When you take a COVID antibody test, they are usually testing for the presence of 2 of 5 kinds of immunoglobulin (antibody) isotypes — IgG and IgM. Interpreting your results depends on a variety of factors such as whether you are asymptomatic or symptomatic, and the absence or presence of IgG and IgM and their quantity.

Why is this important? Well, in the aforementioned studies, the COVID antibodies that crossed the blood-placental barrier were IgG antibodies — the most common antibody found in human blood. IgG antibodies will protect your baby until their own immune system is operational and provide long-term immunity after vaccination or infection. It is hoped that the COVID IgG will do the same for the coronavirus.

Furthermore, none of the babies in the study had IgM in their blood. Because IgM is usually the first response in the event of an infection, the lack of IgM suggests that the babies had not been infected with the coronavirus.

What does this mean in terms of COVID protection for babies?

Ultimately, this data should help health care providers save the lives of babies. Maternal vaccinations are effective means in preventing infant death from diseases and infections that used to affect newborns. If moms can pass along COVID-19 antibodies to their babies, not only can this impact maternal vaccination recommendations, it can also provide some immunity protection — although it is unknown just how much protection and for how long — for the babies right after birth.

Just like the Tdap vaccine has been administered to women in their third trimester since 2012 in order to safeguard newborns, so scientists are hoping that adding the COVID vaccine at some point in the pregnancy would provide the babies with a similar temporary shield against the coronavirus.

What we do (and don’t) know about how the COVID-19 vaccines will protect newborns

At the moment, while the UPenn study shows IgG antibodies can breach the blood-placental barrier, it is still unknown how well these antibodies can protect against COVID-19, how long that protection lasts, and if these babies may later catch COVID-19. Scientists will also need to study when would be the ideal time to vaccinate expectant mothers in order to maximize the antibodies present in newborns at birth — as well as determine if changes in timing would affect how long the IgG antibodies stay in the baby’s body.

Finally, according to the Centers of Disease Control and Prevention (CDC), pregnant people with COVID-19 are at increased risk for severe illness and complications — even death. So, as much as protecting newborns is important, it is of paramount importance to protect the life of the expectant person.

Information about COVID-19 is rapidly changing, and Scary Mommy is committed to providing the most recent data in our coverage. With news being updated so frequently, some of the information in this story may have changed after publication. For this reason, we are encouraging readers to use online resources from local public health departments, the Centers for Disease Control, and the World Health Organization to remain as informed as possible.