The cold could defend us from the new coronavirus

Having previous cold coronavirus infections could protect against Sars-Cov-2. It does not mean, however, that you are immune, but that you develop a milder Covid-19 infection. The Science Hypothesis

(photo: Getty Images) If you have already been infected with the common cold's coronaviruses, your chances of developing a serious Covid-19 infection may be lower. The reason is that these viruses teach our immune system to recognize the new coronavirus. This is the hypothesis, still to be validated, of a team of researchers from the La Jolla Institute for Immunology, according to which the possibility of getting sick of Covid-19, or better of contracting the infection in a milder form, could depend in part how the body previously reacted to cold coronaviruses. Their study has just been published in Science.

Sars-Cov-2, remember, is not the first coronavirus we know: there are in fact four others (HCoV-OC43, HCoV-229E, HcoV-NL63 and HCoV-HKU1) which can cause the common cold. As we told you, previous research by the same research team had already shown how many people, never exposed to the new coronavirus, had immune T cells capable of recognizing some Sars-Cov-2 sites, including the now famous spike protein . Based on this evidence, the researchers of the new study tried to understand the reason, analyzing some blood samples collected between 2015 and 2018 and therefore long before the new coronavirus arrived for the first time in the city of Wuhan.

From the subsequent analysis, the team discovered that T cells present in the samples were able to recognize and react not only to the coronaviruses of common colds, but also to many specific sites of the Sars-Cov-2 . This sort of immunity , say the researchers, derives partially from the memory of the immune system, i.e. the previous responses of T-cells (more precisely, the helper T lymphocytes ) developed against the cousins are less dangerous than the Sars-Cov-2, and in particular, the coronaviruses of common colds. “This study provides direct evidence that memory T cells can identify very similar sequences among the coronaviruses of common colds and Sars-Cov-2” , said Alessandro Sette , one of the authors of the study.

the results of The study, therefore, suggest that the memory of the immune system may help us understand why some people have reported infections from slight from Covid-19 , while others suffer most severely. But not only: in addition to bind to the spike protein, emphasize the researchers, T cells cross-reactive were able to recognize many other viral proteins. A fact that suggests the vaccine against the new coronavirus should not focus only on the spike protein , but take advantage of this cross-reactivity of the T cells to increase the effectiveness of the vaccine .

However, emphasize the researchers, this is only a hypothesis , and will still a lot of work to arrive at the most robust evidence. “Now we have shown that, in some people, the memory of the T cells against the coronaviruses of common colds can also detect the new coronavirus, down to its molecular structures,” explained co-author Daniela Weiskopf . It is plausible, therefore, that this immune reactivity can result in different degrees of protection to the Covid-19 . “Having a strong or best T-lymphocyte response can give you the opportunity to respond much more quickly,” concludes the Seven.