Breastmilk of vaccinated women is key to infant’s immunity against COVID-19
Infants are the group of children most affected by COVID-19 and, nevertheless, lactating women were initially advised to discontinue breastfeeding following mRNA COVID-19 vaccination. Now, a team of researchers from CEDOC – NOVA Medical School, ITQB NOVA and IGC shows that breastmilk can concede protection to breastfeeding children, since it has specific antibodies and spike-reactive T cells.
The infants’ immature immune system relies on the transference of immunity through the breastmilk. However, SARS-CoV-2 immunity transferred from lactating women to their infants is still poorly understood. This study, now published on Cell Reports Medicine, aimed to better understand this process.
Researchers collected and analyzed blood and breastmilk samples of 23 lactating women, before vaccination and after the first and second doses of mRNA COVID-19 vaccine. They detected specific antibodies and spike-reactive T cells in breastmilk of vaccinated lactating women.
“The antibodies found on the breastmilk, named secretory antibodies, possess a component that allows it to survive the harsh conditions of the stomach and successfully reach the infant’s immune system.”, explains Margarida Archer, ITQB NOVA researcher, responsible for the characterization of these molecules. “Such antibodies are produced in the mammary mucosa and passed on to the baby”, adds Diogo Athayde from the Membrane Protein Crystallography Lab.
The study coordinated by CEDOC researcher, Helena Soares, uncovered another interesting finding that upon vaccination breast milk also transfers immunity through spike-reactive T cells – these cells are capable of identifying the spike protein of SARS-CoV-2 and trigger the immune reaction. In the infant, these cells are crucial in mediating vaccine protection. Researchers postulate that these cells protect the baby by setting in the upper respiratory tract and gut. These remain in the system for a long time which suggests that this protection might remain after weaning.
ITQB NOVA researchers Diogo Athayde and Margarida Archer
Original paper:
Cell Reports Medicine | 10.1016/j.xcrm.2021.100468
Secretory IgA and T cells targeting SARS-CoV-2 spike protein are transferred to the breastmilk upon mRNA vaccination
Juliana Gonçalves, Margarida Juliano, Nádia Charepe, Marta Alenquer, Diogo Athayde, Filipe Ferreira, Margarida Archer, Maria João Amorim, Fátima Serrano and Helena Soares
Read the article published on Público newspaper:
"Leite de mães vacinadas tem células de memória contra o SARS-CoV-2" | Público | 03.12.2021
