Background: Since the announcement of COVID-19 in the last of 2019, it has been associated with respiratory systems, particularly the lungs. With increasing number of cases, reports from various research centers revealed that COVID-19 could have different routes and can be found in different organs and tissues. Accordingly, new effects of Coronavirus are expected to be encountered with time. The distribution of the virus in different tissues may explain its neuropathy, diabetic complications, its viral load, in addition to genetic polymorphism. Negative effects of Coronavirus in brain have been documented in some studies. In a recent study, it has been concluded that a deterioration in the structure of the brain tissue and influences in brain micro-environment help in worsening the pathologic course of COVID-19. Furthermore, vaccination side effects are varied and include various clinical presentations. The precise mechanisms beyond these phenomena are not well known.

The aims of the present special issue are to bring the efforts of scientists to participate in providing better understanding of the COVID-19 pathogenesis, clinical presentation, and the impact of vaccinations on public.

Several variants of COVID-19 have been reported, with different symptoms and accompanied pathology. The significance of this special edition comes from reporting and documenting various effects of Corona virus in different systems, organs, and tissues.