not very good. With the drug Valtrex or possibly Famvir, the likelihood of transmission is greatly reduced. However, I would advise you to use condoms every single time and possibly have the person who does not have hsv take a 500mg dose of valtrex to prevent transmission altogether. If Valtrex is given early enough (within like a few hours) it can prevent transmission altogether. This is because it kills the virus before it even has a chance to establish itself in the nerve ganglia. If you are in a relationship where one person has HSV and the other does not, you have a very difficult decision to make. If you really love them and want to have children, would you be willing to contract herpes for that? Its not lethal and just more annoying than anything. Like I said, the best way is just preventative therapy. Take valtrex before you **** the person who has herpes to prevent transmission. No guarantee but I'd say it would reduce the odds by atleast 90%!!!

NurseJohn