The current study — published online Nov. 3 in JAMA Network Open — included 22 newborns born to mothers who tested positive for SARS-CoV-2 at delivery. Only one infant tested positive for the infection right after birth; one more later tested positive days later.
Carsetti’s team found that at 2 months of age, infants who were breastfed showed antibodies against the spike protein in their saliva. That was not true of babies who were exclusively formula-fed.
When the researchers tested moms’ breast milk samples, they found that all harbored those key complexes — antibodies with spike protein bound to them. Levels were particularly high two days after delivery; they’d declined by the two-month mark.
The study is important because it’s the first demonstration that breastfeeding can “actively stimulate” an infant’s immune system to make salivary antibodies against SARS-CoV-2, said Dr. Lori Feldman-Winter.
Feldman-Winter, a professor of pediatrics at Cooper Medical School of Rowan University in Camden, N.J., chairs the American Academy of Pediatrics’ section on breastfeeding.
“Human milk is known to participate in programming the infant’s immune system during the first few days of life,” she said. “Therefore, mothers’ milk following COVID infection activated their infants’ immune system to produce COVID-specific salivary antibodies, whereas formula feeding infants did not produce this response.”
Carsetti said research is ongoing, both to confirm the current findings and to see whether infants born to vaccinated moms also show signs that their immune systems have been actively stimulated against the virus.
Like Tan, she pointed out that when pregnant women get vaccinated, their antibodies are passed through the placenta.
The American College of Obstetricians and Gynecologists has more on COVID-19, pregnancy and breastfeeding.
SOURCES: Rita Carsetti, MD, Diagnostic Immunology Clinical Unit, Bambino Gesù Children’s Hospital, Rome, Italy; Tina Tan, MD, professor, pediatrics, Northwestern University Feinberg School of Medicine, Chicago, and spokeswoman, Infectious Diseases Society of America, Arlington, Va.; Lori Feldman-Winter, MD, MPH, professor, pediatrics, Cooper Medical School of Rowan University, Camden, N.J.; JAMA Network Open, Nov. 3, 2021, online