T cells (also called T lymphocytes) are one of the major components of the adaptive immune system.
Their roles include directly killing infected host cells, activating other immune cells, producing cytokines and regulating the immune response.
According to recent research natural exposure or infection with the novel coronavirus may “prevent recurrent episodes of severe COVID-19”.
The study found SARS-CoV-2-specific T cells even in family members who have been exposed to the virus but have tested negative on antibody blood tests.
All categories of people recovered from moderate or severe COVID-19 disease, or in the convalescent phase after mild or severe disease or exposed family members or healthy people exhibited “robust memory T cell responses months after infection, even in the absence of detectable circulating antibodies specific for SARS-CoV-2.
This indicates a previously unanticipated degree of population-level immunity against COVID-19.
This implies that seroprevalence (the level of a pathogen in a population, as measured in blood serum) as an indicator may underestimate the extent of immunity in the population.
Even as antibodies wane with time, robust T cell memory formed after SARS-CoV-2 infection suggests that “potent adaptive immunity is maintained to provide protection against severe re-infection”.
