The Immunopathology of Covid-19

SARS-CoV-2 is a virus causing Covid-19, with a genome encoding proteins for replication. The innate immune system responds rapidly, employing pattern recognition receptors (PRRs) detecting viral presence. Mucosal tissues offer initial defense, with interferons inhibiting viral replication. Inflammatory cytokines and chemokines attract immune cells, sometimes resulting in cytokine storm. However, excessive inflammation may worsen disease outcomes. The adaptive immune system, comprising CD4+ T cells, CD8+ T cells, and B cells, organize targeted responses. CD4+ T cells activate immune cells and coordinate responses, while CD8+ T cells eliminate infected cells using cytotoxic molecules. B cells produce antibodies that neutralize the virus. Memory B and T cells provide long-term immunity, aiding rapid response upon reinfection. Recovered individuals often exhibit reduced reinfection risks due to memory immunity. Vaccines, like mRNA-based and viral vector-based types, stimulate similar immune responses, bolstering immunity and reducing severe illness.