Our previous paper described the significant upregulation of Angiotensin‐converting enzyme 2 (ACE2) and Dipeptidyl peptidase‐4 (DPP4) genes in naso‐oropharyngeal swabs (NPS) of COVID‐19 patients, thus suggesting that these receptors may play an important and complementary role in virus entry and in the onset and progression of disease.21 This evidence concerns the gene DPP4 and COVID-19.