What is the role of T cells in Covid-19 infection?

T-cells are a type of lymphocyte that play a crucial role in the body’s immune response to COVID-19 infection. The membrane surface on T cells have specialized receptors called T cell receptors (TCRs) that can recognize small pieces of the virus (antigens) presented on the surface of infected cells.

The COVID-19 infection is caused by the SARS-CoV-2 virus. When the SARS-CoV-2 virus enters the body, T cells are activated to recognize and target infected cells. 

Cytotoxic T cells, a type of T cell, are responsible for directly attacking and killing infected cells to prevent the virus from spreading further. Meanwhile, helper T cells signal other immune system cells and coordinate an effective immune response. 

After recovering from Covid-19, some T cells develop immunologic memory. These cells "remember" the virus, allowing the immune system to respond faster and more effectively if the person is exposed to the virus again in the future.

In some cases, the immune response, including T cell activity, can become overactive, leading to excessive inflammation and damage to the body's tissues. This is one reason why severe Covid-19 cases may occur.