By analyzing blood samples from individuals infected with SARS-CoV-2, researchers in Singapore have begun to unpack the different responses by the body's T cells that determine whether or not an individual develops COVID-19. The study, published today in the Journal of Experimental Medicine (JEM), suggests that clearing the virus without developing symptoms requires T cells to mount an efficient immune response that produces a careful balance of pro- and anti-inflammatory molecules.
Many people infected with the SARS-CoV-2 virus do not develop any symptoms, and the infection is cleared by both antibodies and T cells that specifically recognize the virus. In some cases, however, this protective immune response can trigger excessive inflammation that damages tissues and causes many of the symptoms associated with COVID-19.