The study by Zheng et al. (2020) investigates the functional exhaustion of cytotoxic lymphocytes, such as cytotoxic T lymphocytes (CTLs) and natural killer (NK) cells, in patients with COVID-19. The authors found that the total number of NK and CD8+ T cells was significantly reduced in patients with SARS-CoV-2 infection, and these cells exhibited functional exhaustion characterized by increased expression of NKG2A. In patients who recovered after therapy, the number of NK and CD8+ T cells increased, along with reduced NKG2A expression. These findings suggest that SARS-CoV-2 infection may lead to early breakdown of antiviral immunity through the functional exhaustion of cytotoxic lymphocytes. The study also highlights the potential role of NKG2A as a novel inhibitory molecule in immune checkpoint blockade, which could be targeted to prevent functional exhaustion and enhance virus elimination in the early stages of SARS-CoV-2 infection.The study by Zheng et al. (2020) investigates the functional exhaustion of cytotoxic lymphocytes, such as cytotoxic T lymphocytes (CTLs) and natural killer (NK) cells, in patients with COVID-19. The authors found that the total number of NK and CD8+ T cells was significantly reduced in patients with SARS-CoV-2 infection, and these cells exhibited functional exhaustion characterized by increased expression of NKG2A. In patients who recovered after therapy, the number of NK and CD8+ T cells increased, along with reduced NKG2A expression. These findings suggest that SARS-CoV-2 infection may lead to early breakdown of antiviral immunity through the functional exhaustion of cytotoxic lymphocytes. The study also highlights the potential role of NKG2A as a novel inhibitory molecule in immune checkpoint blockade, which could be targeted to prevent functional exhaustion and enhance virus elimination in the early stages of SARS-CoV-2 infection.