Abstract
Immunity to the SARS-CoV-2 virus ensures protection against reinfection by this virus thanks to the combined action of neutralizing antibodies and T lymphocytes specific to viral proteins, in particular the Spike protein. It must be distinguished from the immune response that ensures healing of the infection following contamination that involves innate immunity, particularly type 1 interferons, and which is followed by adaptive cellular and humoral immunity. The importance of the effect of interferons is highlighted by the occurrence of severe forms of the disease in genetically deficient subjects or in patients with antibodies neutralizing type 1 interferon. Herd immunity is not an individual biological property. It is a mathematical property that qualifies the fact that when the proportion of subjects with individual immunity is high enough, there is little chance that an epidemic can occur. The level of that proportion-the herd immunity of the population can be computed under theoretical, often unrealistic, hypotheses, and is difficult to assess in natural conditions.
Highlights
Disparaître l’épidémie a été calculé dans des modèles mathématiques supposant la panmixie ; il est difficile à évaluer dans les populations réelles
Individual immunity is the protection conferred to an individual by the immune response to a viral infection against reinfection with the same virus
Immunity can have deleterious effects spontaneously, as in the case of auto immune diseases, or secondary to certain treatments and even when it deploys uncontrolled defense mechanisms against an infectious disease
Summary
The immune system’s main function is to protect from infections. This ensures the cure of the vast majority of COVID-19 cases and forms the basis for the use of vaccines. In the vast majority of cases (about 85%), the disease regresses spontaneously as a result of the adaptive immune response and is accompanied by protective immunity [4] This immune response involves both antibodies and T cells. Anti-SARS-CoV-2 T cells appear at the end of the first week after contamination They are specific for the various peptides that make up viral proteins, including the Spike protein. The role of the potential pathogenic effect of adaptive immunity, in particular anti-viral CD8+ T lymphocytes, remains to be elucidated They can themselves give rise to the release of cytokines and, above all, to the destruction of pulmonary and endothelial cells infected by the virus. A similar situation has already been described for other proteins in which the absence of the coding gene with neutralizing auto antibodies
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