CD46 and COVID-19: We ruled out this possibility after finding similar levels of C3b deposition on T cells independent of their activation status, although the amplitude of the ex vivo C3b deposition we found on COVID-19 lymphocytes might be partially explained by CD46 binding to CD3b secreted by other cells, such as tissue activated T cells and/or other hematopoietic and non-hematopoietic cells (27), specifically during COVID-19 infection (39).