COVID-19 vaccine side effects: The positives about feeling bad

Abstract

The side effects of SARS-CoV-2 vaccines are often troubling but may merely reflect transient production of type I interferons, a normal physiological response to contact with invading microorganisms.

Fig. 1.. mRNA vaccine activation of DC and induction of IFN-I.

After uptake, mRNA is translated into spike protein and presented as cell-surface MHC-bound peptides to CD4⁺ and CD8⁺ T cells. Cytosolic sensing of RNA by RIG-I and MDA5 plus TLR binding within endosomes leads to activation of IFN regulatory factor 3/7 (IRF3/7) and nuclear factor κB (NF-κB), which bind to DNA inducing gene transcription, and production of IFN-I and proinflammatory cytokines, respectively. MAVS, mitochondrial antiviral-signaling protein. Through up-regulation of DC costimulatory molecules, production of stimulatory cytokines, and a direct action on T cells, IFN-I guides and promotes the adaptive immune response of T and B cells.