Abstract
SARS-CoV-2 primarily causes mucosal infections of the respiratory or intestinal tract. This virus, unlike other viruses responsible for similar mucosal infections, is characterized by an extraordinary ability to modify the immune response at several levels and thus cause a range of clinical complications.
These manipulations create a false picture of pyogenic bacterial infection. The course of the disease is mainly determined by the natural mucosal immunity which can stop the virus from multiplying in the early stages of infection before it can exert its influence.
COVID-19 has two main clinical forms: mucosal infection (respiratory or intestinal) and pneumonia. Pneumonia is associated with activation of the vascular endothelium and a procoagulant state.
Viremia does not belong to the standard course of the disease. Affecting organs other than the lungs - whether during an active infection or later (long covid) - is usually caused by immunopathological reactions or hormonal regulation disorders.