A baby girl born to a partially vaccinated healthcare worker has COVID-19 antibodies

• A Florida baby may be first reported case to have COVID-19 antibodies from her mom's vaccine.
• COVID-positive moms can pass antibodies to their babies in utero, too.
• More research is needed on vaccines during pregnancy.

A baby girl born three weeks after her mom got the first dose of Moderna's COVID-19 vaccine has antibodies against the virus, a February pre-print paper reported.

After getting the shot, the mom, a healthcare worker in Florida, developed COVID-19 antibodies.

Testing revealed those antibodies passed through the placenta to offer some potential protection to her future child, according to the authors at Florida Atlantic University.

While past reports have shown how moms who've had COVID-19 can deliver babies with antibodies, the authors believe theirs is the first to record how vaccines during pregnancy may do the same.

It's not clear how protective or long-lasting the antibodies are

Authors Dr. Paul Gilbert and Dr. Chad Rudnick called their report a lucky "opportunity study," since they were able to find, and follow, a pregnant person who never tested positive for COVID but got the vaccine late in pregnancy and early in the rollout.

When the baby - "a vigorous, healthy, full-term girl," according to the paper - was born, the doctors tested her cord blood for antibodies made from the vaccine, along with conducting other typical tests like for blood type.

They were able to detect COVID-19 IgG antibodies (the type that indicate recovery), suggesting the baby has some protection against the virus, though how much or how long it lasts isn't clear. Future research should illuminate if there's an ideal time for a pregnant person to get vaccinated to maximize protection against the virus for her child.

The authors say their results were expected based on what's known about how the vaccine, and others recommended during pregnancy like the flu vaccine, work.

Past research has shown COVID-19 antibodies seem to cross the placenta

Past studies have suggested that COVID-positive mothers can pass on IgG antibodies against the virus to their fetuses in utero.

One March 2020 paper of six women who tested positive for the virus at delivery, for instance, found five had elevated levels of IgG antibodies even though none had COVID-19.

An October case report also describes an infant born to a mom with asymptomatic COVID-19 who had IgG antibodies but a negative COVID test, demonstrating "passive immunity" through the placenta, the authors write.

And, in November, a woman in Singapore who had COVID-19 in March 2020 gave birth to a baby who has antibodies that seem to be protective against the virus.

Still, more research is needed to understand how severity of illness affects antibody levels, how time of infection during pregnancy plays a role, and how strong and long-lasting babies' presumed immunity is.

Even more research is needed on vaccinations in pregnant women, who were excluded from the first clinical trials. While the shots are expected to be safe in pregnancy and no increase in complications have been reported, it will take time for thorough trial data to be collected and published.

Until then, most professional and governmental organizations encourage pregnant people to make a decision that's right for them, based on their occupation, rates of transmission in their community, underlying health conditions, and other factors.

Whatever the choice, "you should feel like your decision is respected," Dr. Jessica Madden, a pediatrician and neonatologist who serves as medical director of Aeroflow Breastpumps, previously told Insider.