New clues as to why Covid affects men twice as much as women

It is not the first time that this aspect has been discussed and the statistics are clear: covid kills many more men than women. Why? Some new clues emerge from a recent report, by two scientists from Yale University, which explores the various ways in which immune responses differ between the sexes, with important implications for Covid-19.

Despite the fact that scientists from all over the world have now been wondering about the various characteristics of the new coronavirus for about a year, it is still not clear why mortality from Covid is higher among men.

Advanced age is known to be one of the main risk factors, there is no doubt about this but, for the same years, the mortality among elderly men is double that of women. As they explained Takehiro Takahashi and Akiko Iwasaki, Yale University immunologists, in their article published on Science, the differences between the sexes extend far beyond the sexual organs.

Men and women have a different functioning of the immune system, in general, women have a more effective immune system. For example, they generate more immunity against flu than men after being vaccinated, while men with HIV tend to have a higher viral load than infected women.

An immune force that manifests itself from the first months of life: girls are much more resistant than children to infections but also to wars, famines and other calamities.

What does all this have to do with Covid? It has to do with the fact that the death caused by the coronavirus is not so much due to the presence of the virus as to the dysfunctional reaction of the patient’s body.

A few days after infection, there are people who start producing large amounts of inflammatory proteins which, in theory, should alert the immune system. But sometimes that inflammatory overload, on the contrary, breaks down the defenses. This is the famous cytokine storm which has been talked about so much in recent months, which generates an excess of inflammatory molecules that can aggravate the clinical situation of the infected patient leading to death.

The most interesting thing pointed out by the experts is that the production of these molecules is much more common in men than in women, especially in old age. In addition, older men generate fewer T lymphocytes, which can identify and destroy infected cells.

The general model suggests that there may also be biological factors behind the discrepancy between men and women.

From a biological point of view, a man is characterized by having only one X chromosome, inherited from his mother, and one Y chromosome, from his father, while a woman has two copies of the X chromosome, one from each parent. The X chromosome contains several genes that are essential for the proper functioning of the immune system.

Although only one of its two copies of the X chromosome is normally active, it is not always the same.

“This phenomenon means that roughly 50% of a woman’s cells will use the copy of the X chromosome that her father passed on to her and the other 50% will use the mother’s. If a woman has a defect in one of the immune system genes on the X chromosome, it could be corrected because not all of her cells will use the damaged copy, ”explained José Luis Labandeira, professor of human anatomy at the University of Santiago de Compostela. to El Pais.