The objective of the proposed study is to develop an effective NK cell therapy for COVID-19. It has been shown that both the number and the function of NK cells decreased markedly in COVID-19 patients, especially in patients with moderate to severe cases. We therefore propose to generate NK cells from human pluripotent stem cells (PSCs) and use these NK cells for therapy against COVD-19. With the generous support from CIRM, we have differentiated both human iPSCs and ESCs into NK cells and shown that these PSC-derived NK cells can clear SARS-CoV-2-infected cells and protect un-infected cells. Therefore, the human PSC-derived NK cells can serve as a potent immunotherapy.