While a latex condom does in fact stop the herpes virus from crossing from one side to the other, and in doing so greatly reduces the risk, it is not a perfect protection from herpes. This is because of the highly contagious nature of the herpes virus.
While a latex condom does in fact stop the herpes virus from crossing from one side to the other, and in doing so greatly reduces the risk, it is not a perfect protection from herpes. This is because the herpes virus is not only restricted to the the area the condom covers, but rather the whole genital area.
Extra care should be taken if either of the partners have any blisters present, since these essentially are virus-filled colonies. It is recommended that you refrain from having sex when blisters are present because of this reason, and also because during a period of outbreaks you are much more likely to get infected with HIV.