Why children are spared severe forms

Since the start of the Covid-19 pandemic, age has been identified as a major risk factor for developing a severe form.

Unlike adults, especially the elderly who are highly susceptible to infection, children usually have no clinical signs of illness (or only mild symptoms).

Researchers from Inserm and the University of Angers hypothesized that the younger ones were protected by a stronger local innate immune response in the pharyngeal mucosa.

Remember that innate immunity is the immediate response that occurs locally at the point of entry of the pathogen. This is the first barrier of defense.

strong immunity

When cells are infected with any virus, they quickly produce type I and III interferon, which are powerful natural antiviral molecules. Interferon because it “interferes” with the replication of the virus and protects neighboring cells from infection.

So the scientists analyzed nasopharyngeal swabs from 226 people who came for a PCR test at Angers University Hospital from March 2020 to March 2021.

« Les enfants âgés de moins de 15 ans ont une expression accrue d’interférons de type III, molécules peu inflammatoires et d’action locale, qui contrôlent le virus localement au niveau de son point d’entrée, dansoph la mungéuse nas» researchers.

“On the contrary, adults, especially the elderly, preferentially express type I interferon, which is an inflammatory substance and has a more systemic action (throughout the body).”

These findings help explain why children are less susceptible to critical forms of Covid-19 than adults. Type III interferon, which acts primarily by local protection of the epithelium, can control infection at the point of entry, without causing excessive generalized inflammation, thus preventing slipping into the inflammatory storm with the massive cell destruction we see in severe forms”, emphasized Pascal. Jeanine (university professor and hospital practitioner) and Dominique Quez (university professor) in Angers, who led this work.

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