Furthermore, it was demonstrated that the abundance of CD15+ neutrophils and CatG transcripts was elevated in COVID-19 patients [12], increased concentrations of NE and CatG were determined in nasopharyngeal swabs of patients with SARS-CoV-2 [13], and levels of CatG in plasma were increasingly higher starting with the control group to moderate, severe, and critical COVID-19 conditions [14]. Here, CTSG is linked to COVID-19.