Kovir, also known as Oseltamivir phosphate granules, this drug has mainly preventive and therapeutic effects against influenza. Oseltamivir phosphate is the precursor drug of the active metabolite, which is a selective inhibitor of influenza virus neuraminidase, a glycoprotein on the surface of the virus, and the activity is important for the release of newly generated viral particles from lung infected cells, while the infectious further dissemination has a very important role. The active metabolite of oseltamivir phosphate inhibits the neuraminidase activity of influenza A and B viruses, and this drug plays a therapeutic and preventive role in influenza by inhibiting the release of viruses from infected cells, thereby reducing the spread of influenza A or B viruses. This drug is clinically indicated for the treatment of influenza A and B. It can also be used for the prevention of influenza A and B.