Herpes Simplex virus stays dormant in your body for the rest of your life. It breaks out as a cold sore whenever your immune system is weakened.

Herpes virus travels through the sensory neuron (taste buds) to the trigeminal ganglion - nerve intersection close to where your jaws meet
There are symptom relievers once the blister breaks out, but as of now the medicine has no cure for it. However, I got rid of my herpes 10 years ago!