T cell response in patients with COVID-19.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was the third zoonotic coronavirus to have an outbreak in the first two decades of the 21st century. Human-to-human transmission of this virus has threatened thousands of lives around the world. SARS-CoV-2 shares 79% and 50% sequence homology with severe acute respiratory syndrome coronavirus (SARS-CoV) and Middle East respiratory syndrome coronavirus (MERS-CoV), respectively. Like SARS-CoV and MERS-CoV infection, evidence has shown that SARS-CoV-2 infection also causes acute tissue damage due to a pathological immune response, particularly in severe cases. T cells play an important role in virus clearance and prevention, and in this paper, we summarize dynamic changes in the T cell count, subsets, phenotype, and function in Coronavirus Disease 2019 (COVID-19) patients based on current clinical reports. This review may help to better understand the pathological immune response of T cells and facilitate making better therapeutic strategies for patients with SARS-CoV-2 infection.