PROS1 and COVID-19: Furthermore, we demonstrated that T cells recognized all three tested SARS-CoV-2 peptide pools, but the largest proportion of SARS-CoV-2 specific T cells in patients with a mild course recognized peptides from protein N and protein S. These findings are in accordance to the literature, since Ni and colleagues previously reported that mild COVID-19 patients showed a robust T cell response for viral M, N and S proteins, which subsequently shifted to only N-specific T cells in about one-third of the cases post recovery (18).