Tamiflu - how long does this drug stay in your system?

I was recently put on tamiflu capsules. I had to take a tamiflu capsule once daily for ten days. Adult tamiflu stays in ur system until it breaks down the viral antibodies and completes its task. I asked the ER doctor whom prescribed me this medication how long it sit in my system and his direct answer was, "It may vary on the persons immune system and the type of flu virus tamiflu is trying fight away." So, Adults and children using tamiflu wanting to know how long this medication stays in your/their systems, well it may vary on the persons flu, and or body's immune systems.