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With the reopening of schools after months of distance education around the world, the fear that the return to the classrooms of millions of children will generate new waves of contagion, even because of the greater difficulty they would have to comply with hygiene regulations. and basic caution, it was real. But the way the school years have passed reinforces the idea that children are not over-transmitting the new coronavirus (unlike the flu), they are not infected to the same extent as adults, and the development of serious diseases is. very rare in pediatric age.
If infected, most young children have mild or no symptoms. There have even been cases of children who are known to have contracted the virus but who tested negative in PCR tests, very sensitive to the presence of these particles in the body.
An article published this week in the scientific journal Nature puts the characteristics of the immune system of the very young at the center of the answer. “There are increasing signs that children’s immune systems are better equipped to clear SARS-CoV-2 than adults,” the article writes.
“Children are very well prepared to respond to new viruses,” Donna Farber, an immunologist at Columbia University in New York, told the magazine.
The magazine recalls a study in which three brothers developed specific antibodies against the new coronavirus, and two of them showed mild symptoms of covid, but none were positive in PCR tests. This despite having carried out 11 tests over a month in which they were always in contact with their parents, who were also infected.
The immune system triggers the r responsequick
The immunologist who accompanied this Australian family explains that the children’s immune system “manages to trigger a very fast and effective response that cancels the virus even before it has a chance to replicate to the point of being detected in the swab collection” .
Along the same lines, Donna Farber cites other research that has shown that children and young people develop antibodies that respond to the SARS-CoV-2 spike protein, used by the virus to bind to human cells, while adults produce another directed response. to a different protein that is associated with the replication of the virus in the body.
“The youngest do not have the latter antibodies, which indicates that they are not affected by generalized infections. The immune response seems to be able to eliminate the virus before it replicates on a large scale ”, the immunologist tells Nature.
For the Spanish newspaper “El País”, Rodríguez Bano, head of the infectious diseases unit at Hospital Universitário Virgen Macarena, recalls how important the speed of response is to avoid initial viral replication: “A single SARS-CoV2 particle can make 100 thousand copies of itself in 24 hours ”.
Fewer virus receptors in children
Experts have also pointed out that the innate immune system, and not the one that humans develop as they discover new pathogens capable of causing disease, is more effective for this coronavirus. Still, it is acquired immunity that may determine the end of this pandemic, with the most advanced vaccines at the moment focusing precisely on the human body’s ability to recognize the spike protein of this virus and generate the appropriate response.
The fact that children have a lot of contact with seasonal coronaviruses, which cause colds, for example, and antibodies against those agents can also provide additional protection can also help a better response.
Since the beginning of the new coronavirus, researchers have also pointed to the fact that ACE2 receptors, used by SARS-CoV-2 to bind to human cells and that are present in cells of the nose, for example, multiply at the same time. as age advances. What would facilitate the entry of the virus into the body of the elderly.
“The reasons why covid-19 will affect children more and more adults will be many. Biology is rarely that linear, ”says Alasdair Munro, a researcher at Southhampton University Hospital in the UK, also heard by Nature.
Few outbreaks in schools and among students
According to figures from the World Health Organization on cases monitored between January and July, only 1.2% corresponded to children aged 0 to 4 years, 2.5% to the age group of 5 to 14 years and the 9.6% to adolescents and young adults between 15 and 24 years old.
An investigation published in the Lancet magazine this week and which analyzed the epidemiological situation in schools in England after its reopening in June concluded that “infections and outbreaks were rare in schools” in that period, that the incidence was higher between teaching and non-teaching staff than between children and young people and that there was a strong association between outbreaks and the level of virus transmission in the community where the school was located.
