COVID Antibodies in Breastmilk

Immunizations & Vaccines • May 18, 2021

COVID Antibodies in Breastmilk: The Invisible Cloak of Protection

Breastmilk is known as Mother Nature’s first and best vaccine.  It is loaded with the accumulated wisdom and knowledge of how best to fight past maternal infections.  Each time a largely defenseless baby cuddles with their mom in this age-old ritual of breastfeeding, an invisible cloak of protection is passed from a mother’s breast to their baby.

Breastmilk & Vaccines

As a high-risk obstetrician, I regularly counsel my patients to take advantage of the ways our bodies are wonderfully made to protect both mom and baby through vaccinations during pregnancy or lactation.  As a breastfeeding mother, working through the pandemic with daily COVID-19 exposures in the hospital—both known and unknown—I prayed that taking the COVID-19 vaccine would teach my body how to fight this ruthless virus.  In turn, I hoped that this wisdom would be passed on to my baby through my milk to protect her, just like the vaccines that came before it.

I received my first COVID-19 vaccine dose on December 21, only ten days after it was approved by the FDA.  Unfortunately, pregnant and lactating people were excluded from the COVID-19 vaccine trials, so I relied heavily on my medical training and prior knowledge of vaccines in breastfeeding to inform my personal vaccine decision as a breastfeeding mother.  Honestly, it wasn’t hard to make.  I’d seen COVID-19 up close and personal and knew it to be a formidable foe—a patient pregnant, happy, and healthy one day and in the intensive care unit with a machine breathing for her and pumping the blood through her body a few days later.  That known risk seemed infinitely greater than the theoretical risk of the vaccine.  But beyond fear of my own occupational hazard, I hoped I’d get twice the bang for my buck like we see with so many other vaccines.  For example, I’d received the flu vaccine just a few months earlier with the knowledge that the antibodies[1] my body made in response would reduce my little girl’s chance of getting the flu by around 60%.  There was no reason to believe that the COVID-19 vaccine wouldn’t do the same thing, but I didn’t know on December 21, 2020.

Researching the COVID Vaccine for Breastfeeding Moms & Babies

I’m truly blessed to have fellow mama docs in my life whom I call my “work angels.”  We take care of each other, cover for one another when our kids are sick, bounce around random ideas, provide moral support on tough days, and talk about life, liberty, and the pursuit of happiness over lunch.  It was during one of these angel lunches a few days after my vaccine with two of my Washington University high-risk Ob/Gyn colleagues, Drs. Jeannie Kelly and Nan Raghuraman, that Dr. Kelly said, “There’s nothing out there about the COVID-19 vaccine for breastfeeding moms and babies—we should do a study!”

The beautiful thing about working with angels is that they can move heaven and earth.  We quickly got the necessary approvals and pulled together a dream team from Barnes-Jewish Hospital, St. Louis Children’s Hospital and the Washington University School of Medicine, including Dr. Misty Good from pediatrics, who had the expertise and lab to test whether breastmilk had antibodies. And, we had no problem finding vaccinated volunteers to donate breastmilk with help from Chanill Henley on our Washington University research team.  Chanill literally ran all over the medical school campus collecting and protecting our precious breast milk samples since they needed to be stored under strict conditions.  I happily volunteered my milk too—I wanted to contribute to the greater good, but I also wanted to know if my body was sending antibodies of COVID-19 protection through my breastmilk to my baby.

COVID Antibodies in Breastmilk

I received my second dose on January 8 and collected numerous samples of my breastmilk at various time points from vaccination.  By late February, we finally had enough samples to run the antibody tests in Dr. Good’s lab.  We were so excited!  I waited with bated breath to see if the COVID-19 vaccine would follow in the footsteps of the vaccines that came before it, and we were not disappointed.  There were antibodies in the breastmilk—mine and the other volunteers, and that antibody response endured for the duration of the entire study, which was 80 days after vaccination!  We still didn’t have proof of exactly what that meant for the babies, but I took great comfort in knowing that my body was taking the wisdom it learned from the COVID-19 vaccine and passing antibodies, through my breastmilk, to my baby.

Learn more about this new research study:


My wish:

May my little one be wrapped in an invisible cloak of protection, even as we see the devastation of the COVID-19 pandemic in the world around us. 

May mothers and babies around the world have access to this same privilege to be vaccinated and protected. 

May those who are given the opportunity for vaccination and the invisible cloak of protection seize it!



[1] Antibodies are the soldiers in our body that get activated by seeing an invader—either a bacteria, virus, or an imitator in the form of a vaccine—and rise up as an army to attack the invader and protect us


Kelly JC, Carter EB, Raghuraman N, Nolan LS, Gong Q, Lewis AN, Good M. Anti-SARS-CoV-2 antibodies induced in breast milk after Pfizer-BioNTech/BNT162b2 vaccination. American Journal of Obstetrics and Gynecology. March 30, 2021. DOI:


The COVID breastfeeding study was supported in part by the Foundation for Barnes-Jewish Hospital through a generous donation from the Lowenhaupt Family; the Institute of Clinical and Translational Sciences, Washington University in St. Louis, which is, in part, supported by the Clinical and Translational Science Award under grant number UL1TR002345 from the National Institutes of Health (NIH)/National Center for Advancing Translational Sciences; NIH grants 5T32HD043010 and R01DK118568, the St. Louis Children’s Hospital Foundation, the Children’s Discovery Institute of Washington University and St. Louis Children’s Hospital, and the Department of Pediatrics at Washington University School of Medicine in St. Louis.