The immune system of children would be more effective in defeating the Covid-19 virus but would not memorize it.
- As of January 28, 2023, there have been 4,513 new cases of Covid-19 in the past 24 hours, according to Santé Publique France.
- As of January 26, 2023, the percentage of the population having received a booster vaccination was 60.4%.
Our body – or more precisely some of our immune cells – keeps the memory of the infections it has already fought, according to National Institute of Health and Medical Research (Inserm). But this would be less the case for children with regard to Covid-19, according to a study which has just been published in the journal Clinical Immunology.
Covid-19: children are more at risk of being reinfected
“The children were not exposed to many viruses, explains Professor Tri Phan, one of the main authors. Because they do not develop memory T cells, they are at risk of becoming ill when reinfected. As they get older, with each new infectious episode, their T cells are at risk of “depleting” and [devenir] ineffective, such as T cells in the elderly”.
When a pathogen first enters the body, the immune system sets up a first line of defense to immediately fight the intruder. In parallel, a second line of defense is set up with the B lymphocytes, which produce antibodies adapted to the virus, and the T lymphocytes, which will in particular recognize and destroy the cells which it has infected. After infection, all these lines of defense disappear and only B and T lymphocytes remain, which have become “memory” lymphocytes. In the event of a new infection, they will be immediately reactivated. Thus, the response of the immune system will be more specific, rapid and effective.
Memory T cells less effective in children
To analyze how the little ones’ immune system worked, the researchers analyzed the T cells and cellular immune responses of a small group of children and their families. Either they had no symptoms of Covid-19 or they had only very mild ones.
So they discovered that the children had a lot of T cells that had never encountered Covid, but could fight this virus. In contrast, after recovery, their memory T cells were not functioning.
In adults, participants had few T cells that had never encountered Covid but their post-recovery memory T cells performed much better than those of children.
The authors therefore recommend vaccination against Covid-19 for children in order to preserve their immune system and prevent them from getting too sick.
