Hepatitis is a liver inflammation which has different etiologies, it can be caused pharmacologically or can be associated with fatty liver or alcohol consumption. However, viral infection as the most important cause. Recently, the World Health Organization (WHO) has published reports of outbreaks of hepatitis of unknown etiology in several countries in children less than 16 years. In this review we describe the general aspects of viral hepatitis, the molecular description of the hepatotropic viruses, laboratory findings, molecular diagnosis, prevention strategies. In addition, the main characteristics of some viruses that are not hepatotropic but have been previously reported to be related to some types of hepatitis are mentioned. Finally, a brief description of new cases of hepatitis of unknown origin is given and the adverse effects of SARS COV-2 vaccines are briefly discussed.