some people may fight it without knowing it

If some still nickname it “new coronavirus”, the SARS-CoV-2 coronavirus, at the origin of the current pandemic of COVID-19, is not as innovative as it looks. This new virus is a close relative of pre-existing betacoronavirus, sometimes of an epidemic nature such as SARS-CoV or MERS-CoV. It also shares a relationship with alphacoronaviruses, some of which, in humans, are the cause of common rhinitis (or colds). Its molecular structure and its mode of action are therefore not that foreign to our body. This has just been demonstrated by a new scientific study published in the prestigious journal Nature. The latter attests that even people who have never been infected with the COVID-19 coronavirus have immune cells capable of recognizing and reacting to the virus.

Pre-existing cross-immunity

83% of patients with COVID-19 have lymphocytes T CD4+ capable of recognizing an antigen (segment of viral particle of interest for immune cells) specific for the SARS-CoV-2 coronavirus, the S-glycoprotein. CD4 + LTs do not produceantibody but can induce B lymphocytes to produce them in order to formulate an immune response. This same type of CD4 + T lymphocytes was also found in 35% of perfectly healthy volunteers, who had never encountered this virus.. The CD4 + LTs extracted from the latter’s blood reacted equally to similar antigenic particles from human alphacoronavirus 229E as from human beta-coronavirus OC43, each causing a common cold. According to the researchers, this means that there is a cross immunity which allows some people, who have battled several colds in the past, to fight the COVID-19 coronavirus as if they had already come across it. “The clinical impact of pre-existing T lymphocytes reactive to the SARS-CoV-2 coronavirus deserves to be studied on a larger scale, emphasizes the Berlin researchers behind the study. Their presence in a large fraction of the population could have important implications for vaccine formulation. “

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