COVID-19 vaccines for infants have not been developed yet, but a new report reveals the potential of getting some protection from their vaccinated moms through breastfeeding.

Dr. Dolores Sabina Romero Ramrez and Dr. Mara Magdalena Lara Péreza, together with colleagues at the University Hospital of the Nuestra Señora de Candelaria in Spain, examined the concentration of antibodies to the SARS-CoV-2 virus in the breastmilk of COVID-vaccinated mothers in a recent study published in Pediatrics.

There was widespread fear at the start of the pandemic that the SARS-CoV-2 virus could be transmitted to infants through breast milk; however, science has proven that human milk is not a route of infection for the virus.

The second topic addressed in this current study is if breastfeeding from moms who have received the COVID-19 vaccine may be protective to their infants. We know that breastfeeding has powerful immunoprotective effects, but is it effective in passing on SARS-CoV-2 protective antibodies to an infant?

The authors of this intriguing study, which ran from Feb. 2 to Apr. 4, recruited a convenience sample of healthcare professionals who were breastfeeding their infants at the time of their COVID-19 vaccine. The day after their second dose of vaccine, 100 women were invited (94% received Pfizer and 6% received Moderna). The control group consisted of 24 unvaccinated women who were breastfeeding and had never had COVID-19.

On day 14 following the second vaccine shot, blood and breast milk samples were taken. All of the vaccinated women produced neutralizing antibody titers as defined by the vaccine makers, whereas none of the unvaccinated women had any detectable neutralizing antibody.

There were no antibodies identified in the control group's breastmilk. However, all vaccinated subjects had IgG antibodies and 89% had IgA antibodies against SARS-CoV-2 in their milk, and there was a substantial favorable relation between maternal blood and breastmilk antibody levels.

Vaccinated mothers breastfed for an average of 11 months in this study, and while breastfeeding duration was not clearly associated with antibody levels for periods less than 24 months, this is an area for future research.

Will nursing be the most effective strategy to protect infants and toddlers under the age of two against SARS-CoV-2? This exciting story, like so many others surrounding COVID-19, is still unfolding, and this research adds to the puzzle.