The first epidemiological data from China and Italy show that Covid-19 affects men more than women. A reality that can be explained by several factors related to lifestyle and biological order.
- In China and Italy, 60% of patients are men
- Estrogen improves immune response in women
The progression of the pandemic and the weather allow us to have the first data related to the coronavirus. It appears that Covid-19 affects and kills more men than women. The figures obtained in Italy and China, the two countries currently most affected by the pandemic, reveal that 60% of the sick are men who also represent 70% of the deceased patients, according to the Italian National Public Health Agency. A disparity which was also observed for example for the SARS epidemic in 2003.
Estrogen as the main factor
The factors explaining this gender inequality in the face of this pandemic would be multiple. Jean-Charles Guéry, head of the Inserm research team “Sex-related differences in immunity: mechanisms and physiopathology” in Toulouse, sees several elements to explain this difference. “Some would be related to lifestyledevelops for Science and Future. For example, in China, men smoke more than women and also have higher rates of type 2 diabetes and high blood pressure. Other factors would be biological, with women developing immune responses of greater amplitude and better quality than men in response to viral infections or vaccines..” This greater immune response in women is also justified here by several reasons: sex hormones such as estrogens which can regulate the cells of the immune system and genetic factors with the X chromosome which women have in duplicate and which carry many immunity genes.
For the SARS epidemic in 2003, results conducted on mice showed the positive effect of estrogen in explaining the difference between men and women. “There is clearly a protective effect of this moleculereplies Jean-Charles Guéry. When mice are infected with SARS, the mortality of males is much higher than that of females. When female ovaries (and thus the source of estrogen) are removed, or when they are treated with drugs that block the estrogen receptor (such as those used in the treatment of breast cancer), mortality increases to that more than 80% males. Whether this is a direct effect on the immune system or other tissues is unknown at this time..”
All blood groups are not equal in the face of the disease
For the moment, it is difficult to say with certainty that the same thing is happening with Covid-19, since the only sources available are epidemiological data in Italy and China. “Further studies will be needed in humans and animals to better understand the mechanisms responsible for this sex bias.”, justifies the researcher. It seems that women have an advantage against the virus which is also found with the vaccine against the flu since they develop an effective immunity with a vaccine dose half that of men. Enough to give ideas for the future potential vaccine against Covid-19 where “adding estrogen-based supplementation or related molecules to the future vaccine against SARS-Cov-2 could make it much more effective.concludes Jean-Charles Guéry.
Another genetic chance, the blood groups would not all be equal in the face of the disease. According to a Chinese study, conducted by the University of Shenzhen, people with blood group O are better immunized against the coronavirus than other groups and present a 33% lower risk of infection. Conversely, people in group A have an additional risk of infection of 20%. The explanation lies in the antibodies, which are more important in people with blood group O.
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