IFNA1 and COVID-19: The study found no significant difference between the cellular components (T and B cells, NK, innate lymphoid cells (ILCs), neutrophils, macrophages and dendritic cells) in breast milk before and during infection; however, there was a qualitative change in the percentage of macrophages expressing IFNα (a type I interferon) in the breast milk sample with active COVID-19, which showed an 8-fold increase compared to the milk collected before infection [127].