Differences in the immune system and better health of the blood vessels They are among the factors that protect children from the severity of COVID-19.
It is assured by experts from Murdoch Children’s Research Institute (MCRI), la Melbourne University and the Freiburg University who have reviewed a large amount of world literature on covid-19 and publish it in «Archives of Disease in Childhood».
Until now, there were a number of hypotheses that provided possible explanations for why adults were at increased risk and children were protected from serious illness and death from COVID-19, but most did not explain why the severity of COVID-19 increases. abruptly after the age of 60-70 years.
It was striking that, in contrast to other respiratory viruses, severe illness and death from COVID-19 have been relatively rare in children.
“Most children with COVID-19 have no or only mild symptoms, such as fever, cough, sore throat, and changes in the sense of smell or taste; even children with the usual risk factors for serious infections, such as immunosuppression, were not at high risk for serious disease», Says Nigel Curtis, author of the report
Curtis explains that damage to the thin layer of endothelial cells that line various organs, especially blood vessels, the heart, and lymph vessels, increases with age and there is an association between the conditions that affect these cells and the more serious covid-19.
«We know that the pre-existing damage of blood vessels plays an important role in the severity of covid-19 and can lead to blood clots, leading to strokes and heart attacks. Covid-19 can infect these endothelial cells and cause inflammation of the blood vessels, “he says.
However, in children the endothelium has experienced much less damage compared to adults and their coagulation system is also different, which makes children are less prone to abnormal blood clotting.
And furthermore, the most recent immunization with live vaccines, such as the measles mumps and rubella vaccine, which could boost the immune system, could play a role in protecting children.
For Petra Zimmermann from Freiburg University there are other important differences in the immune system between children and adults. “The children have a stronger innate immune response, which is the first line defense against covid-19 ».
Another important factor, he points out, is the ‘trained immunity‘which’ primes innate immune cells after mild infections and vaccinations, leading to a type of ‘innate immune memory’.
Children infected with Covid-19 often have co-infections with other viruses. Recurrent viral infections could lead to better trained immunity, making children more effective at eliminating covid-19
Likewise, according to the work, the levels of microbiota (bacteria and other germs) in the throat, noise, lungs and stomach also influence the susceptibility to COVID-19.
«The microbiota plays an important role in the regulation of immunity, inflammation and in defense against diseases. Children are more likely to have viruses and bacteria, especially in the nose, where these insects can limit the growth of covid-19 ”, says this researcher.