Of course, the illness cannot get worse without the virus first infecting a cell, and then replicating in that cell to infect other cells in the body, and then

Of course, the illness cannot get worse without the virus first infecting a cell, and then replicating in that cell to infect other cells in the body, and then potentially infecting other hosts; that is how a virus works, right? Now, if replication is stopped, AND the body is able to destroy the first infected cell, then the patient is cured, but otherwise? I guess that even if the body's immune system cannot get rid of that "patient cell zero", it is quite possible that a 6 month period is enough for the cell to die from the virus. I do not have any medical training though, so please correct me if I am wrong.