Infant Passive Protection Against Coronavirus Through Exclusive Breastfeeding: A Cross-Sectional Study

Area of Science:

• Immunology
• Public Health
• Pediatrics

Background:

• Maternal vaccination against SARS-CoV-2 (COVID-19) is crucial for infant protection.
• Understanding the impact of different vaccine technologies on breast milk antibody levels is essential.
• The Omicron variant presents unique challenges for vaccine-induced immunity.

Purpose of the Study:

• To determine the presence and duration of neutralizing antibodies against the Omicron variant in human milk post-SARS-CoV-2 vaccination.
• To compare antibody induction across different vaccine technologies (AstraZeneca, Pfizer, CoronaVac, Janssen) used in Brazil.
• To assess the influence of vaccination dosage and breastfeeding exclusivity on antibody levels.

Main Methods:

• Cross-sectional study involving lactating women in Rio de Janeiro (April-October 2022).
• Analysis of breast milk samples for Omicron-specific neutralizing antibodies.
• Comparison of antibody levels based on vaccine type, number of doses, and breastfeeding practices.

Main Results:

• All vaccine types effectively induced neutralizing antibodies in breast milk against the Omicron variant.
• No significant difference in antibody levels was observed between two or three vaccine doses.
• Exclusive breastfeeding was significantly associated with higher percentages of neutralizing antibodies in breast milk.

Conclusions:

• Maternal SARS-CoV-2 vaccination contributes to passive immunity in infants via breast milk.
• Breastfeeding is a vital strategy for providing infants with protection against respiratory viruses.
• These findings support breastfeeding, particularly when infant vaccination is not yet recommended.