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Critical elements of the body’s immune system are T-cells, a class of lymphocytes that promote an appropriate immune response and actively engage in the destruction of pathogens. Findings from two new studies suggest that people who are infected with SARS-CoV-2, the virus that causes COVID-19, have T-cells that target the virus.
The first of the two studies analyzed blood samples collected 20 to 35 days after the onset of symptoms in 20 non-hospitalized COVID-19 patients who were no longer symptomatic. All of the COVID-19 patients that were tested carried SARS-CoV-2 specific helper T-cells and nearly three-quarters carried natural killer T-cells.
The authors of the study also investigated whether people who haven’t been infected with SARS-CoV-2 might have immunity to the virus by analyzing blood samples from 2015 to 2018, well before the pandemic began. They found that roughly half of the samples had helper T-cells that recognized SARS-CoV-2.
Similar results were found in the second study, which analyzed blood samples from 18 people with COVID-19. Their findings demonstrated that 83 percent of COVID-19 patients carried helper T-cells and 35 percent of uninfected people carried helper T-cells. The authors of both studies suggested that this cross-reactivity likely stems from a previous infection with coronaviruses that cause colds.
These findings suggest that a subset of the population might be better equipped to fight of infection from SARS-CoV-2 due to previous exposure to other coronaviruses.