Higher expression of MMP2 has been found in the tracheal-aspirate fluid samples of patients with severe COVID-19 patients [39]; however, we found decreased expression of MMP2 in the nasopharyngeal milieu in patients with severe COVID-19, which may suggest differences in the expression of MMPs may vary in different anatomical locations and/or cells [40,41]. Here, MMP2 is linked to COVID-19.