A study conducted at Tongji Hospital in Wuhan, China, analyzed the immune responses of 452 patients with coronavirus 2019 (COVID-19) admitted between January 10 and February 12, 2020. The study aimed to compare the immune profiles of severe and non-severe cases. Results showed that severe cases had significantly lower lymphocyte counts, higher neutrophil counts, and a higher neutrophil-to-lymphocyte ratio (NLR) compared to non-severe cases. Severe cases also exhibited reduced percentages of monocytes, eosinophils, and basophils, along with elevated levels of infection-related biomarkers and inflammatory cytokines. T-cell counts were significantly lower in severe cases, with both helper T (Th) cells and suppressor T cells below normal levels. The percentage of naive Th cells increased, while memory Th cells decreased in severe cases. Regulatory T cells were also lower in severe cases, indicating a more pronounced immune dysfunction. The study suggests that the novel coronavirus primarily affects lymphocytes, especially T lymphocytes, leading to immune dysregulation. Monitoring NLR and lymphocyte subsets can aid in the early detection and management of severe COVID-19. The findings highlight the importance of immune surveillance in identifying critical illness and guiding treatment. The study also notes that older men with comorbidities are more susceptible to severe COVID-19, likely due to weakened immune function. The immune response in severe cases was characterized by increased pro-inflammatory cytokines and chemokines, which may contribute to the development of a cytokine storm. The study underscores the role of immune dysregulation in the pathogenesis of severe COVID-19, emphasizing the need for further research to understand the mechanisms underlying this immune response.A study conducted at Tongji Hospital in Wuhan, China, analyzed the immune responses of 452 patients with coronavirus 2019 (COVID-19) admitted between January 10 and February 12, 2020. The study aimed to compare the immune profiles of severe and non-severe cases. Results showed that severe cases had significantly lower lymphocyte counts, higher neutrophil counts, and a higher neutrophil-to-lymphocyte ratio (NLR) compared to non-severe cases. Severe cases also exhibited reduced percentages of monocytes, eosinophils, and basophils, along with elevated levels of infection-related biomarkers and inflammatory cytokines. T-cell counts were significantly lower in severe cases, with both helper T (Th) cells and suppressor T cells below normal levels. The percentage of naive Th cells increased, while memory Th cells decreased in severe cases. Regulatory T cells were also lower in severe cases, indicating a more pronounced immune dysfunction. The study suggests that the novel coronavirus primarily affects lymphocytes, especially T lymphocytes, leading to immune dysregulation. Monitoring NLR and lymphocyte subsets can aid in the early detection and management of severe COVID-19. The findings highlight the importance of immune surveillance in identifying critical illness and guiding treatment. The study also notes that older men with comorbidities are more susceptible to severe COVID-19, likely due to weakened immune function. The immune response in severe cases was characterized by increased pro-inflammatory cytokines and chemokines, which may contribute to the development of a cytokine storm. The study underscores the role of immune dysregulation in the pathogenesis of severe COVID-19, emphasizing the need for further research to understand the mechanisms underlying this immune response.