In children under ten years of age, the gene of one of the coronavirus cell receptors weakly works, so the virus is probably more difficult to penetrate into children’s cells.
Different people get different coronavirus infections with COVID-19. It is known that SARS-CoV-2 virus is more dangerous for old people than for young people, that men are more sensitive to this virus than women, and children can not be afraid of it at all. Only 2% of cases of coronavirus infection occur in children, who also carry it very easily, or even without symptoms; deaths among children are extremely rare. Which, by the way, is very different from the situation with the flu, which children suffer harder than adults – including because their immunity is not quite ripe and has not yet encountered the flu at all.
Researchers from Mount Sinai Medical Center in an article on the portal JAMA Network put forward one of the possible reasons why the virus, you can say, almost does not touch the children. Actually, we can assume that the virus is more difficult to penetrate into children’s cells, and if it is difficult to penetrate, then the point is in the cellular receptors that it uses to enter. We have repeatedly spoken about the “co-shaped” receptors: these are two enzymes sitting on the outer cell membrane – ACE2 and TMPRSS2. Different cells synthesize them in different quantities. For example, ACE2 protein (or an angiotensin-converting enzyme that not only regulates blood pressure, but also plays a role in the immune system) synthesizes testes cells a lot – this is probably why the virus lingers in the male body longer than in the female.
As many probably guessed, children have less ACE2 than adults. The authors analyzed the activity of the ACE2 gene in epithelial cells from the nose taken from more than three hundred people from 2015 to 2018. It turned out that the ACE2 gene is least active in children under 10 years of age, but with age, its activity is steadily increasing. Perhaps the virus because it almost does not harm children, because it is very difficult for him to penetrate into their cells.
However, this is exactly what is “possible.” Although the ACE2 gene in children does not work as actively as in adults, the activity of the enzyme itself may depend on many factors – for example, on the presence of other proteins that work differently at different ages. In addition, ACE2 is present not only in the epithelium of the nose, but also in the lungs and intestines, and there the gene can activate in some other way. Perhaps the children are protected from the virus by some other molecular mechanisms; however, ACE2 gene activity can still play a role. And let the children hardly get COVID-19, the more we know about how the virus interacts with a person, even a child, even an adult, the sooner we will understand how to tame it.
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