Scientists from the Berlin Institute of Health at Charité (BIH), together with colleagues from Charité – Universitätsmedizin Berlin and the university hospitals in Bonn and Aachen, have found a type of immune cells that is particularly active in severely ill COVID-19 patients. The CD16 positive T cells have an increased cytotoxic effect, especially on the inner cell layer of blood vessels. Their presence, along with complement system factors, is associated with a highly fatal outcome of the disease. The scientists have just published their findings in the scientific journal Cell.