Influenza virus is one of genera of Orthomyxoviruses. It belongs to RNA viruses’ family. Influenza virus is of 3 types: Influenza virus A, Influenza virus B, Influenza virus C. Influenza virus causes disease influenza (flu). Flu is a contagious disease, spreads very easily and attacks all age groups. It is a common viral infection leading to a deadly effect. This disease can be prevented partly by vaccination.