Question: We heard a study recently saying breast milk from vaccinated moms was providing antibodies to babies. Any idea how strong that protection is? 

Answer: There is some promising new research out!  Here are a few highlights:

• American Journal of Obstetrics and Gynecology recently published this study, COVID-19 vaccine response in pregnant and lactating women: a cohort study, which observed levels of antibody production after 1st and 2nd doses of vaccination among pregnant and lactating women (in maternal blood, umbilical blood, and breastmilk).  Researchers also included in their study pregnant women who had been naturally infected with SARS-CoV-2 in order to compare vaccine-derived antibody production and infection-derived antibody production.  Among the findings were these three important nuggets: 
  • COVID mRNA vaccines generated robust immunity in pregnant and lactating women; 
  • Vaccine-induced immune responses were significantly greater than the response to natural infection; 
  • Vaccination resulted in robust antibody circulation in breast milk, indicating that breast milk could confer immunity to neonates.
• JAMA recently published this research, SARS-CoV-2–Specific Antibodies in Breast Milk After COVID-19 Vaccination of Breastfeeding Women, which also investigated “whether maternal immunization results in secretion of SARS-CoV-2 antibodies into breast milk.”  Here, the main findings are: 
  • Yes, post-vaccination (and for the six week study follow-up period), there was “robust secretion of SARS-CoV-2 specific IgA and IgG antibodies in breast milk.”; and 
  • These types of antibodies have been shown to have “strong neutralizing effects, suggesting a potential protective effect against infection in the infant.”

We still don’t have direct evidence of protection conferred from breast milk, the strength of protection conferred, and how that protection may be modified based on various characteristics (like breastfed child’s age).  More still to come. That said, the accumulating evidence is indeed very promising!