TMPRSS2 and COVID-19: However, on inspection of the SARS-CoV-2-associated host factors, we found that several immune cells (such as dendritic cells, plasmacytoid dendritic cells, monocytes, T cells, etc.)were enriched similarly across the different COVID-19 patients, indicating that ACE2 and TMPRSS2 may be insufficient to study SARS-CoV-2 infection.