Does a mother receiving Covid (Coronavirus disease) and influenza vaccines transfer antibodies through breastmilk to a four-month-old infant?

Maternal COVID-19 and Influenza Vaccination Transfers Protective Antibodies Through Breastmilk to Infants

Yes, there is strong evidence that a mother receiving COVID-19 and influenza vaccines transfers protective antibodies through breastmilk to a four-month-old baby, providing passive immunity against these infections. 1

Evidence for Antibody Transfer Through Breastmilk

Influenza Vaccine

• Breastfeeding mothers vaccinated against influenza produce breast milk containing higher levels of influenza-specific immunoglobulin A (IgA) antibodies 1
• These antibodies have been found to persist in breast milk for up to 6 months after birth, providing ongoing protection to the infant 2
• Greater exclusivity of breastfeeding in the first 6 months of life decreases episodes of respiratory illness with fever in infants of vaccinated mothers 1
• Breastfeeding activates innate antiviral mechanisms in infants, specifically type-1 interferons, which further protect against influenza viruses 1

COVID-19 Vaccine

• Based on the biology of other vaccines, there is potential for neonatal benefit as vaccine-stimulated immunoglobulin A passes through breast milk and provides additional protection against SARS-CoV-2 infection 1
• Vaccine-related mRNA has not been detected in breast milk studies, supporting the safety of COVID-19 vaccination for breastfeeding mothers 1
• Experts from the Academy of Breastfeeding Medicine and American College of Obstetricians and Gynecologists agree that COVID-19 vaccination poses minimal to no potential risk to the breastfed infant 1

Combined Protection Mechanisms

• Maternal vaccination provides dual protection pathways for infants:
  1. Transplacental antibody transfer during pregnancy (primarily IgG antibodies) 1
  2. Breast milk transfer of antibodies (primarily IgA) after birth 1
• For a four-month-old infant, these complementary protection mechanisms are particularly valuable as they are too young to receive influenza or COVID-19 vaccines directly 3, 4

Effectiveness of Maternal Vaccination for Infant Protection

• Infants born to mothers vaccinated against influenza during pregnancy have a 72% risk reduction for laboratory-confirmed influenza hospitalization in the first few months of life 1, 2
• Maternal COVID-19 vaccination during pregnancy provides 35% effectiveness against COVID-19-related hospitalization among infants under 6 months and 54% effectiveness for infants under 3 months 3
• This protection extends through breastfeeding, with continued antibody transfer providing additional immune support 1

Clinical Recommendations

• Both influenza and COVID-19 vaccines are recommended for breastfeeding mothers to protect both themselves and their infants 1
• Vaccination during breastfeeding is safe for both mothers and their infants 1
• For maximum protection, mothers should receive both vaccines as soon as they are available, ideally by the end of October 2
• Both vaccines can be administered simultaneously at different anatomic sites to improve vaccination coverage and efficiency 2

Important Considerations

• The infant's regular vaccination schedule should proceed as planned regardless of maternal vaccination status 2
• Live attenuated influenza vaccines are contraindicated during pregnancy but are safe during breastfeeding 1, 2
• The protection provided through breast milk complements the transplacental antibody transfer that occurred during pregnancy 1, 4
• Maternal vaccination represents an important strategy to protect young infants who are too young to be vaccinated themselves 5, 6