... which were sent to the CDC to be sure I wasn't a carrier. Symmetrel was used for the cure. Then I was told to use every year during flu season for prevention. It, with the flu shot, has worked but my current primary physicianr indicated last year that it wasn't a preventative. I am on it only during flu season and stop taking around May and restart in September. Is this a good course of prevention to use? It has worked so far.