In the early months of vaccine rollout, when babies were still too young to be protected by any shot, a small group of nursing health care workers offered a quiet hope: that the protection their bodies built might travel, through milk, to the children they feed. The study that tested this idea is modest, and its authors are careful not to claim more than their twenty-one participants can support. Yet it arrives at a moment when the old human arrangement of mother-to-infant protection is being asked to carry new weight, as a delta surge presses on pregnant women who have not yet been vaccinated
mRNA COVID Vaccines Produce Antibodies in Breast Milk, Small Study Finds
Unvaccinated pregnant women with COVID-19 face much greater risk of serious illness, and some Alabama patients required emergency C-sections while intubated.
Babies can't be vaccinated right now, so their protection comes from Mom.
Mark
What did the researchers actually find?
Mimi
Milk from 21 nursing health care workers was tested before vaccination, after dose one, and after dose two. Antibodies rose after each shot, reaching about 100-fold once the women were fully vaccinated.
Mark
Is that more than natural infection produces?
Mimi
The study says the levels exceeded what tends to occur after infection with the virus itself.
Luke
Let's be careful there. Twenty-one people is a very small group, all health care workers. Antibodies in milk are a measurement, not proof that babies are protected.
Mimi
Agreed. Researchers say they don't yet know how much protection infants get or how long it lasts.
Mark
So why does it matter?
Mimi
Babies can't be vaccinated, and they rely on what their mothers pass along. Larkin says that gives the findings potential significance.
Luke
And Johnson & Johnson wasn't studied, so nothing here speaks to that vaccine. Larkin says that work is happening, but there are no results yet.
Mark
Does this put pressure on mothers who can't breastfeed?
Mimi
Larkin says he didn't intend that. He notes vaccination may still help through the placenta, and cocooning protects babies too. The placenta point is described as suggested by studies, not settled.
Il Polso
- A small study of 21 lactating health workers found mRNA vaccines pushed antibodies in breast milk up roughly 100-fold after full vaccination.
- The findings land in the middle of a delta surge, with fewer than one in four pregnant women in the U.S. vaccinated.
- Researchers cannot yet say how much protection these antibodies give an infant or how long it lasts, and Johnson & Johnson was not included.
- Hospitals are seeing more sick pregnant patients, including Alabama cases where doctors performed emergency C-sections on intubated women.
- Scientists urge vaccinating parents and caregivers as a shield for infants too young to be vaccinated, while younger children wait for eligibility.
In the early months of vaccine rollout, when babies were still too young to be protected by any shot, a small group of nursing health care workers offered a quiet hope: that the protection their bodies built might travel, through milk, to the children they feed. The study that tested this idea is modest, and its authors are careful not to claim more than their twenty-one participants can support. Yet it arrives at a moment when the old human arrangement of mother-to-infant protection is being asked to carry new weight, as a delta surge presses on pregnant women who have not yet been vaccinated.
Last winter, as Pfizer and Moderna vaccines first reached health care workers, researchers began collecting breast milk from women who were nursing and had just received their shots. Their study, published this week in Breastfeeding Medicine, followed 21 lactating health workers, a small group, but one of the first to examine what an mRNA vaccine does to the milk a baby drinks.
The researchers measured milk at three points: before vaccination, after the first dose, and after the second. Each shot raised coronavirus antibodies, and after full vaccination the increase reached roughly 100-fold, higher than what infection itself tends to produce. Joseph Larkin III, the senior author at the University of Florida, explained that newborns depend on their mothers for much of their early protection, and that antibodies in milk could pass that shield along. Babies cannot yet be vaccinated, which is why he thinks this matters now.
He was equally careful about the limits. No one knows how much protection an infant gains or for how long. The group was small because vaccines were then limited to health workers, and Johnson & Johnson was not studied, though research on it is underway. Larkin also stressed that breastfeeding is hard, and that mothers who cannot nurse should not feel discouraged, since vaccination still protects their babies. Vaccinating those around an infant, a practice called cocooning, works alongside masking and caution indoors.
All of this unfolds against a surge of the delta variant and low uptake among pregnant women, fewer than one in four in the U.S. The CDC has called vaccination for pregnant and breastfeeding people more urgent than ever. In Alabama, a fetal medicine specialist described unvaccinated pregnant patients so sick that doctors had at times performed emergency C-sections on intubated women. Experts hope that growing evidence will persuade more women to roll up their sleeves, while younger children wait for their own turn at protection.
Last winter, when the Pfizer and Moderna vaccines first reached health care workers, a team of researchers began collecting breast milk from women who were nursing and had just rolled up their sleeves. The study they built from those samples, published this week in the journal Breastfeeding Medicine, followed 21 lactating health care workers. It is small, and it is among the first looks at what an mRNA vaccine does to the milk a baby drinks.
The researchers analyzed each woman's milk at three points: before vaccination, after the first dose, and after the second. After every shot, the level of coronavirus antibodies in the milk rose. Once the women were fully vaccinated, the increase was roughly 100-fold. According to the study, that is higher than the antibody levels that tend to appear when a woman is infected with the SARS-CoV-2 virus itself.
Joseph Larkin III, the senior author and an associate professor of microbiology and cell science at the University of Florida, explained the logic to HuffPost. Newborns have a relatively immature immune system that develops over time, so their major protections come from their mothers. If a mother is producing antibodies that show up in her milk, he said, that protection has the potential to pass to the baby. He stressed why it matters now: babies cannot be vaccinated.
The limits are real. Researchers still do not know how much protection those antibodies give an infant or how long it lasts. The study was conducted when vaccines were available only to health care workers, which is why the group was so small. It also did not include the Johnson & Johnson vaccine, though Larkin said research on that vaccine is under way.
Larkin was careful about how the findings should be read. Breastfeeding is hard, he noted. Most mothers in the United States start out nursing, but fewer than 60 percent are still doing so at six months, and pressure to breastfeed can harm mental health. As a father of five, he said, he understands some of the challenges from the outside. Mothers who cannot breastfeed, for whatever reason, should not be disheartened, he said, because by being vaccinated they are still giving their babies a layer of protection. Other studies have suggested that SARS-CoV-2 antibodies can cross the placenta. Vaccinating parents and others who spend time with unvaccinated infants also "cocoons" those babies, a measure that works alongside masking and limiting time in indoor public spaces.
The backdrop is a delta surge and low uptake. Fewer than one in four pregnant women in the U.S. has received a dose of a COVID-19 vaccine. The Centers for Disease Control and Prevention has said vaccinating people who are trying to conceive, pregnant, or breastfeeding is more urgent than ever. Unvaccinated pregnant women who contract COVID-19 face a much greater risk of serious illness, and hospitals around the country are reporting more pregnant patients. A fetal medicine specialist in Alabama told The Daily Beast about the terrifying toll the delta variant is taking on unvaccinated pregnant women there, saying doctors have at times performed emergency C-sections on intubated patients. Pediatric coronavirus cases are also climbing.
Experts hope the growing body of research will persuade more women to get vaccinated. Young children remain ineligible, though they are likely to qualify this fall or winter, with those aged 5 to 11 expected to come first and younger children after. Until then, Larkin said, protecting those who cannot protect themselves is very important.
Citazioni salienti
Mothers who cannot breastfeed shouldn't be disheartened, because by being vaccinated they still provide a layer of protection for their baby.— Joseph Larkin III, University of Florida (paraphrased)
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