ABSTRACT
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is widely spread due to its strong infectivity by close contact via droplets or skin touch. With fever or cough as the first symptom, some patients suffering from coronavirus disease 2019 (COVID-19) quickly progressed to serious condition, which severely threatened the health of patients. As immunodeficiency is a significant factor of the poor condition, the relationship between COVID-19 and T-lymphocyte subsets will be summarized. The paper is written to indicate the clinical significance of T-lymphocyte subsets in the monitoring and treatment of COVID-19. It is suggested that the subgroup levels of T-lymphocyte subsets should be dynamically monitored during the course of disease for better understanding the condition and taking positive intervention, which will provide guidance to control immune inflammatory cascade and hold back the development of critical situation.