The immune system
Immunity is the natural mechanism designed to fight external aggressions to the human body. These so-called aggressors are foreign cells or bodies, recognised as “non-self” by the body, which enter the body through the skin or mucous membranes. This includes, for example, bacteria, viruses, fungi, parasites, allergens, toxic pollutants, etc.
Immunity is provided by the immune system, a highly complex defence system comparable to a legion of tiny soldiers ready to fight when a threat arises.
This system is organised into two lines of defence:
Innate immunity: the fastest, it constantly monitors and prevents infectious agents (aggressors), whatever they may be, from penetrating and multiplying in the body. It calls on several types of “soldiers” (white blood cells, cytokines, interferons, etc.) and protective stratagems (tears, mucus, fever, etc.)
The ability of memory cells also explains why we only get some diseases once, against which we remain “immune”, once. It is this mechanism that is targeted by vaccination: by administering a low dose of an antigen, we stimulate the system to remember its profile and produce specific antibodies.
The particular case of COVID-19
1. Ana B. Pavel et al., Th2/Th1 Cytokine Imbalance Is Associated With Higher COVID-19 Risk Mortality, Front. Genet., 16 July 2021 | https:/doi.org/10.3389/fgene.2021.706902
2. V. Bonny et al., COVID-19 : physiopathologie d’une maladie à plusieurs visages – La Revue de médecine interne 41 (2020) 375–389
Source : https:/www.mongeneraliste.be/nos-dossiers-section/les-infections-virales-bacteriennes/