Covid: Why don’t some people get the virus? – Independent

“I never caught Covid.” We are fewer and fewer when pronouncing this sentence. However, some continue to resist. So how do you explain, after seven waves, that some have never been infected with SARS-CoV-2? Point with Sandrine Sarrazin, an Inserm researcher at the Center for Marseille-Luminy Immunology.

To be or not to be contaminated … Since the spring of 2020, more than 32 million cases of Covid-19 have been identified in France. A number that only reflects a part of reality. For Sandrine Sarrazin, an Inserm researcher at the Center for Marseille-Luminy Immunology, “eAmong the asymptomatic forms that went unnoticed, people who were infected twiceNot to mention the screening campaigns that started well after the first cases showed up and self-tests not counted, it is still difficult today to know how many people have actually been affected by the SARS-2 virus.

However, some did not develop the disease in seven consecutive waves. How do we explain that?

  1. People who are isolated or who have contracted it without knowing it?

It’s hard to imagine people who haven’t been in contact with the virusSandrine Sarrazin notes.But there must be rare cases of people who are very isolated, outside major cities, who never take public transportation, who strictly respect barrier gestures, and who may have survived the virus…but perhaps this is not the majority of those who have never contracted the disease.“Another hypothesis,”Those who had it but had no symptoms, or who thought it was a cold or the flu ‘, and thus whoever imagines himself has slipped through the cracks.

  1. genetic predisposition?

A French team (Inserm/APHP) led by Professor Jean-Laurent Casanova has already shown that genetic and immunological predispositions explain approximately 25% of severe forms of Covid-19, without necessarily having any comorbidities. “, continued the l’immunologiste.”On the contrary, there is no doubt that there are people who are genetically better equipped. The same team is also interested in the genetics of health professionals who were exposed to Sars-CoV-2 before vaccines or masks were available … and who did not contract the disease.. “

Further work on this potential ‘genetic protection’ has already been done. Take, for example, these scholars fromNewcastle University which found that the HLA-DRB1*4:01 gene was found three times more often in people without symptoms. This indicates that carriers of this gene show some level of protection. Note, however, that this gene is directly related to latitude and longitude. Obviously, there are more airlines in Northern and Western Europe. This suggests that European populations are more likely to remain asymptomatic … while they risk passing the disease on to the more susceptible population.

  1. Via immunity?

A recent study published in the journal temper nature Communications showed that exposure to rhinovirus, the most common cause of the common cold, can protect against SARS-CoV-2 infection. In this work, researchers fromImperial University of London It has been found that high levels of T cells that the body generates when infected with other human coronaviruses (such as the common cold), may protect against infection with COVID-19. But this is only a hypothesis.Sandrine Sarrazin, Fury. “Vaccination also generates strong immunity. However, this does not prevent the disease from developing.

  1. blood type?

Since the beginning of the epidemic, scientists have been interested in the relationship between blood type and the risk of infection with the Corona virus. Thus, several scientific publications have noted an association between belonging to group O and protection against Sars-CoV-2 virus. But Sandrine Sarrazin realizes that “We returned from this hypothesis. Because if there was an association in studies between blood type and the severity of Covid cases, there was no evidence of any protection against infection.

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