Abstract: The specific T cell responses of COVID-19 patients, convalescent patients, unexposed individuals and vaccinators, and summarized the population characteristics of T cell immunity to SARS-CoV-2 were reviewed. SARS-CoV-2 can significantly induce T cell responses in COVID-19 patients, and the degree of T cell activation is closely related to the severity of the disease. There are bulk of memory T cells in convalescents that can respond to SARS-CoV-2 antigens. Some T cells of unexposed healthy people can be activated by SARS-CoV-2 antigen, indicating the existence of cross-reaction and preexisting immunity. Vaccination population can induce the production of specific memory lymphocytes to defend against SARS-CoV-2 invasion. Several highly pathogenic SARS-CoV-2 variants (Alpha, Beta, Gamma, Delta, and Omicron variants) were summarized, as well as the effectiveness of current cellular immunity against them, providing a theoretical basis for the development of effective prevention and treatment approaches.

Key words: SARS-CoV-2, T cell response, immune, convalescents