Common cold coronavirus immune cells confer protection against SARS-CoV-2

Immunity keeps track of past infections. Everyone has had a cold, a mild infection sometimes caused by coronavirus. According to a recent study, immune cells formed during a cold may also partially protect against SARS-CoV-2 infections.

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The coronavirus humans, other than those in the SARS family, are responsible for the typical symptoms ofwinter : sore throat, nose flowing and other cold which generally resolve on their own. Previous studies have shown that lymphocytes T specific for these human coronaviruses also recognize their more virulent cousin, the SARS-CoV-2. We can then assume that the presence of these T lymphocytes constitutes a protection, not total, against infections with SARS-CoV-2.

ScientistsImperial College From london have studied this question. Does the presence of T cells specific for other coronaviruses at the time a person is exposed to SARS-CoV-2 influence infection?

More cross-reactive cells in the uninfected?

« Being exposed to SARS-CoV-2 doesn’t always lead to infection, and we wanted to understand why. We have found that high levels of pre-existing T cells, created by the body when infected with other human coronaviruses like the common cold, can protect against Covid-19 infection. », Explains Rhia Kundu, first author of the study.

The study took place in September 2020 among 52 Britons, relatively young, living with someone infected with SARS-CoV-2, and who were therefore at risk of being infected in turn. The participants carried out tests PCR at the start of the experiment, 4 and 7 days later to confirm the infection or not. At the same time, the participants also took a blood test to analyze the presence of the famous T lymphocytes.

The results showed that the 26 uninfected people had more of these so-called cross-reactive cells than the infected people. These T lymphocytes are active against SARS-CoV-2 because they recognize part of the coronavirus that is conserved between all viruses of this family, the nucleocapsid. However, scientists did not observe any differences in S protein-specific T cells between infected and uninfected participants.

In other words, the presence of these T lymphocytes could confer partial protection against infection, but by no means prevent it entirely.

« While this is an important finding, it is only a form of protection, and I want to stress that no one should rely on this alone. However, the best way to protect yourself against Covid-19 is to be fully immunized, including receiving your booster dose », Concludes Rhia Kundu.

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