It was reported that NK cells in the peripheral blood (PB) decreased in patients infected with SARS-CoV-2, especially in severe cases.124 However, another detached study showed no difference in the number of CD16+CD56+ NK cells in mild versus severe cases.125 On the other hand, Maucourant et al. illustrated a detailed NK cell activation landscape in bronchoalveolar lavage from COVID-19 patients126 and identified the hallmarks of these immunotypes, including perforin, NKG2C, and KSP37. Here, NCAM1 is linked to COVID-19.