It looks like one of the strategies that herpes viruses use to defeat immune response is to provide a 'decoy' target for antigens. Attached to the surface of the viral capsid is a glycoprotein, called glycoprotein D, that allows the virus to enter a cell. It seems to have a secondary purpose of prompting an immune response that is only partially effective in fighting infection, thereby allowing the virus to survive the immune response long enough to cause the host to become contagious.
Hosts who have not been infected with either HSV1 or HSV2 are able to acquire immunity with the Einstein vaccine. But if a host has been infected with either HSV1 or HSV2, the vaccine is much less effective. I wonder if lowering the white blood cell count of a host will improve the immune response of the host to the vaccine and allow immunity.