In the present work, we evaluated the biological effect of SARS-CoV-2 infection on MCF7 cells (ER+/PGR+), a model for the luminal A subtype, MDA-MB-231 and HCC1937 cell lines (ER-/PGR-), collectively referred to as triple-negative breast cancer (TNBC) and belonging to the basal B/claudin low and basal A subtypes, respectively12. This evidence concerns the gene ESR1 and triple-negative breast carcinoma.