why is it hard to get rid of viuses?!

Why is it hard to get rid of viruses? This is what I know. If you get viruses inside of your body, the virus kind of hunts around for a cell. When it finds a cell it wants to attack it sticks on to that cell and releases its genetic material into it. That causes the cell to become sick and die. After it attacks that cell it keeps hunting around for more cells until a white blood cell can fight it off.