Reports that support the potential benefits of DPP-4 inhibitors in COVID-19 patients mention that DPP-4 was identified as a functional receptor for the spike protein of MERS coronavirus [236] and that antibodies targeting DPP-4 protein inhibited human coronavirus-Erasmus Medical Center infection of Huh-7 cells and primary human bronchial epithelial cells [34]. Here, DPP4 is linked to infection.