Maternal Vaccination and Breastfeeding

Evidence for Antibody Transfer Through Breastmilk

• Breastfeeding mothers vaccinated against influenza produce breast milk containing higher levels of influenza-specific immunoglobulin A (IgA) antibodies, according to the American Academy of Pediatrics 1, 2
• Greater exclusivity of breastfeeding in the first 6 months of life decreases episodes of respiratory illness with fever in infants of vaccinated mothers, as reported by the American Academy of Pediatrics 1, 2
• Breastfeeding activates innate antiviral mechanisms in infants, specifically type-1 interferons, which further protect against influenza viruses, as found by the American Academy of Pediatrics 1, 3
• 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, according to the American College of Obstetricians and Gynecologists 4
• Vaccine-related mRNA has not been detected in breast milk studies, supporting the safety of COVID-19 vaccination for breastfeeding mothers, as confirmed by the American College of Obstetricians and Gynecologists 4
• 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 4, 5

Combined Protection Mechanisms

• Maternal vaccination provides dual protection pathways for infants: transplacental antibody transfer during pregnancy (primarily IgG antibodies) and breast milk transfer of antibodies (primarily IgA) after birth, as described by the American College of Obstetricians and Gynecologists and the American Academy of Pediatrics 1, 2, 6, 7

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, as reported by the American Academy of Pediatrics 7
• This protection extends through breastfeeding, with continued antibody transfer providing additional immune support, according to the American Academy of Pediatrics and the American College of Obstetricians and Gynecologists 1, 4

Clinical Recommendations

• Both influenza and COVID-19 vaccines are recommended for breastfeeding mothers to protect both themselves and their infants, as advised by the American Academy of Pediatrics and the American College of Obstetricians and Gynecologists 1, 5
• Vaccination during breastfeeding is safe for both mothers and their infants, as confirmed by the American Academy of Pediatrics 1, 3

Important Considerations

• Live attenuated influenza vaccines are contraindicated during pregnancy but are safe during breastfeeding, as stated by the American Academy of Pediatrics 2
• The protection provided through breast milk complements the transplacental antibody transfer that occurred during pregnancy, according to the American College of Obstetricians and Gynecologists 6

Optimal Timing for Maternal COVID-19 and Influenza Vaccination

Timing of Maternal Vaccination

• For maximum protection, maternal influenza vaccination should be administered as soon as the seasonal vaccine becomes available, ideally by the end of October, according to the Centers for Disease Control and Prevention 8
• Pregnant women in their third trimester can receive influenza vaccination during July and August because this might reduce the risk of influenza illness in their infants during the first months after birth, as recommended by the Centers for Disease Control and Prevention 8

Effectiveness of Maternal Vaccination for Infant Protection

• Infants born to mothers vaccinated against influenza during pregnancy have a risk reduction of 72% for laboratory-confirmed influenza hospitalization in the first few months of life, according to the American Academy of Pediatrics 9
• Vaccinated pregnant mothers pass IgG antibodies to their offspring through transplacental transfer, with one study showing that transplacental transfer is more likely if the mother is vaccinated in the third trimester, as reported in the medical literature 10
• Sustained high levels of influenza-specific IgA antibodies have been found in the breast milk of women vaccinated against influenza during pregnancy for up to 6 months after birth, according to the American College of Obstetricians and Gynecologists 11

Spacing Between Maternal and Infant Vaccinations

• The infant's 4-month vaccines should proceed as scheduled regardless of when the mother receives her vaccines, as recommended by the American Academy of Pediatrics 12

Vaccine Safety Considerations

• Live attenuated influenza vaccines are contraindicated during pregnancy due to the theoretical risk of placental transmission of the virus to the fetus, according to the American College of Obstetricians and Gynecologists 11
• COVID-19 vaccines are considered safe during pregnancy, with initial safety data supporting the use of mRNA vaccines in pregnant women, as reported by the American College of Obstetricians and Gynecologists 11

Practical Recommendations

• The mother should receive both influenza and COVID-19 vaccines as soon as they are available, ideally by the end of October, as recommended by the Centers for Disease Control and Prevention 8
• Both vaccines can be administered simultaneously at different anatomic sites to improve vaccination coverage and efficiency, according to the Centers for Disease Control and Prevention 13

Common Pitfalls to Avoid

• Unnecessarily postponing the infant's 4-month vaccines due to concerns about interaction with maternal vaccination is not supported by evidence, as stated by the American Academy of Pediatrics 14

Pneumococcal Vaccination During Lactation

Safety Profile for Lactating Women

• The American College of Obstetricians and Gynecologists recommends that pneumococcal vaccination can be safely administered during lactation without any adverse effects on breastmilk composition or the nursing infant, and may actually provide protective antibodies to the baby through breast milk 15
• The Centers for Disease Control and Prevention states that the pneumococcal polysaccharide vaccine is considered safe during breastfeeding, with no documented adverse effects on milk production or infant health 15
• Approximately half of vaccinated individuals develop mild, local reactions (pain, erythema, swelling) lasting less than 48 hours, with rare systemic reactions, according to the CDC 16

Potential Benefits for the Infant

• The American Academy of Pediatrics suggests that vaccination during lactation may provide passive immunity to the nursing infant through antibody transfer, based on the biology of other vaccines, vaccine-stimulated immunoglobulin A (IgA) antibodies can pass through breast milk and provide additional protection against pneumococcal infections 17

Clinical Recommendations

• The American College of Obstetricians and Gynecologists recommends that pneumococcal vaccination should be offered to lactating women when protection is clinically indicated, without any need to interrupt breastfeeding 15
• The CDC states that there is no evidence-based reason to withhold breast milk before or after pneumococcal vaccination, and the vaccine can be administered at any point during lactation without concern for the nursing infant 15
• Lactating women receive the same pneumococcal vaccine formulation and dosing as the general adult population, according to the CDC 16

Important Caveats

• The CDC notes that most safety data for pneumococcal vaccination during lactation is extrapolated from general vaccine biology and post-marketing surveillance rather than dedicated clinical trials 16
• The American College of Obstetricians and Gynecologists states that the available evidence primarily addresses polysaccharide vaccines; conjugate pneumococcal vaccines have similar safety profiles but less specific lactation data 15