Why You Might Want To Breastfeed Longer If You Get Covid, Or The Vaccine

When I tested positive for Covid-19 in February of this year, I had just started transitioning my 6-month-old daughter to formula in the hopes that within a month, my breasts could be mine again. It’s now April, I’m still breastfeeding, and I have no intention of stopping anytime soon. Why? I want to provide my baby with protection from the novel coronavirus as long as I can. And I’m not alone.

As soon as I tested positive, the first thing I asked my doctor was, “Can I continue breastfeeding?” The answer was a resounding yes — and not only could I but I should. Despite every mandate telling those infected with Covid-19 to quarantine, infected mothers are advised by the CDC to continue breastfeeding and pumping, albeit with certain safety precautions. And it’s not just about bonding with our babies.

Not only is there no risk of passing Covid through breast milk — in just one of many similar studies, Michelle McGuire, PhD, director of the University of Idaho's Margaret Ritchie School of Family and Consumer Sciences tells Romper she analyzed milk samples from 300 moms right after women got infected last spring and found no evidence of the virus in their breast milk — studies are showing that breast milk from infected or vaccinated moms offers our babies some protection against the disease.

Rebecca Powell, PhD, a human milk immunologist at New York's Icahn School of Medicine at Mount Sinai, has been studying the human milk immune response to infection and vaccination in order to help facilitate the development of vaccines that protect infants through breastfeeding. Since March of 2020, Powell has collected breast milk samples from over 800 donors across the country who were infected with Covid. She discovered that not only do lactating moms infected with Covid have antibodies in their breast milk that destroy the virus, but that these antibodies are more durable (i.e., they last longer) than the Covid-disabling antibodies found in the blood of those infected.

Further studies also show the vaccine I received this month will further boost the number and type of antibodies I’m passing on to my daughter through my breast milk.

It’s important to note that it’s not as if babies are 100% immune to any disease for which they get antibodies via breast milk, and Covid is no exception. Precautions still need to be taken to minimize risk of and exposure to the disease. Dr. Kirsi Jarvinen-Seppo, the chief of pediatric allergy and immunology at the University of Rochester Medical Center, told the New York Times that the research isn’t there that would allow vaccinated moms to assume their babies are totally immune. “There is no direct evidence that the Covid antibodies in breast milk are protecting the infant — only pieces of evidence suggesting that could be the case,” she told the outlet.

Contrary to popular belief, antibodies passed on via breast milk aren’t permanently ‘implanted’ in the baby.

McGuire asserts that while studies are still too few and too small, it’s reasonable to recommend a mother infected with Covid-19 continue breastfeeding to protect her baby — as well as the people with whom her baby has contact. (A baby can’t be a carrier if they are immune to the virus.) “If I were advising my daughter, I’d tell her that,” she told Romper. “As a lactation physiologist and someone who has studied milk composition for decades, I would suspect that’s true.”

The promising evidence is prompting more and more mothers like me to choose to give their babies the promise of protection. So how does it work?

Breast milk & antibodies 101:

From upper respiratory infections to diabetes, the protection mothers provide their babies through breast milk is called passive immunity, also referred to as passive protection. Contrary to popular belief, antibodies passed on via breast milk aren’t permanently “implanted” in the baby. In fact, the antibodies, which can be found after a feed in the baby’s mouth, nasal cavity, and gut, are eventually washed away by the baby’s own secretions like saliva, mucus, or gastric juices. Antibodies are also impacted by whatever else the baby drinks or eats. Within only a few hours after nursing, antibodies will have disappeared from the baby’s mouth and nasal cavity; a small number might remain in the gut. Lactating mothers replenish the antibodies through subsequent feedings.

The same is true for antibodies that protect against Covid: the more often a baby is breastfed, the more chances they have to get those antibodies and that passive immunity.

“A 3-year-old breastfed once or twice a day isn’t going to be as consistently protected as a 3-month-old breastfed 12 times a day,” says Powell, herself a mother of three. But partial protection is better than no protection. “The antibodies that still remain can mitigate the dose of the virus they are exposed to, or reduce the viral infection by a significant amount,” Powell explains to me over the phone as she breastfeeds her 3-year-old from her home in Brooklyn.

Are there Covid-19 antibodies in breast milk? How long do they last?

When Laura Lopez and her (now) 9-month-old daughter contracted Covid back in November, she began pumping extra breast milk and freezing it. Months later, after feeding her baby, she still gives the extra to her 2-and-a-half-year-old daughter in 10-ounce bottles a couple times a day to offer her protection.

A mother is still passing immunity on to her baby even after the immunity to Covid found in her blood may have significantly decreased. And, perhaps even more amazing: these long-lasting antibodies present in my body as a lactating mom could protect me even after the antibodies in my blood have diminished.

But how long after recovering from Covid will antibodies remain in a person’s bloodstream, or their breast milk? The answer to this question requires a little bit of context:

The dominant antibodies that are present in the milk of lactating mothers after they’ve been infected with Covid-19 are called Secretory Immunoglobulin A (SIgA). The dominant antibodies that develop in the blood of a person who has been infected with Covid (or vaccinated against it) are called Immunoglobulin G (IgG). Both types of antibodies disable the virus, which enters a baby’s body the same way it would attack a grown-up: through “mucosal surfaces” like the nose and mouth (that’s why we wear masks). Secretory antibodies are of special interest to researchers like Powell because their unique “shell” allows them to survive natural enzymes in breast milk and saliva and the acidity of the baby’s gut, meaning they’re more durable than other kinds of antibodies.

Powell told me that the dominant Covid antibodies in blood tend to peak around three weeks after infection and then slowly drop. Eight months after infection, these antibodies are generally still detectable but have notably plateaued compared to the initial peak levels. However, she followed 14 lactating women for ten months and saw very little significant decrease in the secretory antibodies in their breast milk. This suggests that a mother is still passing immunity on to her baby even after the immunity to Covid found in her blood may have significantly decreased. And, perhaps even more amazing: these long-lasting antibodies present in my body as a lactating mom could protect me even after the antibodies in my blood have diminished.

Powell tells me that her study is the first to show how durable these Covid-disabling SIgA antibodies in breast milk are over such a long time.

What about the Covid-19 vaccines and breast milk?

Lopez has now been vaccinated and is continuing to pump, freeze, and serve her milk to her two youngest children. After reading about studies showing that antibodies are transferred via breast milk after the vaccine, Sarah Boyd traveled two hours to get her shot — and she decided to keep breastfeeding her 2-and-a-half-year-old daughter. “I might keep breastfeeding her until she can get a shot if studies show the antibodies stick around that long,” she says.

The latest research shows that vaccinated lactating moms also pass on Covid-disabling antibodies to their babies through breast milk, but these antibodies are the IgG type, not the same kinds of antibodies present in the breast milk of women who contracted Covid. It’s still immunity, though! One study from Washington University School of Medicine in St. Louis found a huge boost in protective antibodies in breast milk two weeks after the first shot. These antibodies were still present 80 days later (the length of the study) and the protection was expected to extend longer. Further, McGuire says that some unpublished studies are reporting vaccinated women with especially high levels of antibodies in their milk — and it’s suspected that these women were previously infected with Covid.

Boyd says that her friends suggested she make her 12-year-old son smoothies with some of her antibody-rich breast milk.

Boyd says that her friends suggested she make her 12-year-old son smoothies with some of her antibody-rich breast milk. “I totally would if I didn’t think it would scar him if he ever found out,” she laughs.

For moms considering freezing antibody-rich milk, Powell says the levels of antibodies in breast milk post-vaccine will likely mirror what’s found in blood. For Moderna and Pfizer vaccines, some antibodies will be present two to three weeks after the first dose, and higher levels will show up about a week after the second dose. For Johnson & Johnson, the levels will increase starting about two weeks after the shot and reach their maximum levels of protection three to four weeks after the shot. It’s anticipated that these antibodies will be present in the breast milk of vaccinated mothers for as long as the vaccine provides her with immunity.

It’s infuriating that breastfeeding isn’t considered early on in [studying] these infectious diseases.

As for giving older kids a splash of “liquid gold” in their morning smoothie, all kidding aside, Powell believes anything that moms can do to reduce stress and feel like they’re “doing something” during these difficult times is positive. However, she says once an individual (whether an 18-month-old or a 12-year-old) is ingesting only a few ounces a day, the potential effect will be low. “Only a large study can determine if there would be some protective effect compared to no [breast] milk at all,” she tells me. “Certainly, nobody should have a false sense of security that this smoothie a day means that the child should be then free to enter into environments that are higher-risk for Covid exposure.”

Future research on breastfeeding & vaccines:

To many scientists, it is still baffling that breastfeeding moms were left out of the vaccine trials. “We have to do this better! The majority of health care workers in the world are women of reproductive age. It’s infuriating that breastfeeding isn’t considered early on in [studying] these infectious diseases,” says McGuire.

“In a perfect world, we’d be designing vaccines with breastfeeding moms in mind,” says Powell, who also praises the science behind the current vaccines. She adds that “there are ways that vaccines could be designed to generate a more natural [breast] milk antibody response” — meaning designed to produce those durable secretory antibodies.

For now, I’ll continue to breastfeed my baby longer than planned.Early studies show that people like me who had Covid and then get vaccinated have super high levels of Covid-disabling antibodies — higher than vaccinated people who never had Covid. Furthermore, Powell says that people who had Covid and then get vaccinated are also the ones best responding to variants of the disease. Perhaps future research will find that lactating moms like me, who were previously infected with Covid and then received a vaccine, are also passing along some sort of super immunity that helps our babies fight off variants.

Update: A previous version of this article misidentified Dr. Powell’s place of residence. She lives in Brooklyn.

Studies referenced:

Alisa Fox, Jessica Marino, Fatima Amanat, Florian Krammer, Jennifer Hahn-Holbrook, Susan Zolla-Pazner, Rebecca L Powell (2020), Robust and Specific Secretory IgA Against SARS-CoV-2 Detected in Human Milk, PubMed, https://pubmed.ncbi.nlm.nih.gov/33134887/

Jill K. Baird, Shawn M. Jensen, Walter J. Urba, Bernard A. Fox, Jason R. Baird (2021), SARS-CoV-2 antibodies detected in human breast milk post-vaccination, medRxiv, https://www.medrxiv.org/content/10.1101/2021.02.23.21252328v2

Kathryn J. Gray, MD PhD, Evan A. Bordt, PhD, Caroline Atyeo, BS, et al (2021), COVID-19 vaccine response in pregnant and lactating women: a cohort study, American Journal of Obstetrics & Gynecology, https://www.ajog.org/article/S0002-9378(21)00187-3/fulltext

Sivan Haia Perl, MD, Atara Uzan-Yulzari, MSc, Hodaya Klainer, BSc (2021), SARS-CoV-2–Specific Antibodies in Breast Milk After COVID-19 Vaccination of Breastfeeding Women, JAMA, https://jamanetwork.com/journals/jama/fullarticle/2778766

Keerti Gedela (2021), Antibody response to first BNT162b2 dose in previously SARS-CoV-2-infected individuals, The Lancet, https://www.thelancet.com/action/showPdf?

Experts:

Rebecca Powell, PhD, a human milk immunologist at New York's Icahn School of Medicine at Mount Sinai

Michelle McGuire, PhD, director of the University of Idaho's Margaret Ritchie School of Family and Consumer Sciences

Dr. Kirsi Jarvinen-Seppo, the chief of pediatric allergy and immunology at the University of Rochester Medical Center