Most vaccines don't "wear off". It depends on the person, not the vaccine. Even people sick with chicken pox once can get it again. All of us are at risk of shingles later on in life after getting chicken pox just once. I have to wonder why there is no herpes vaccine? That virus hides in our body to come bite us in the lip or ***** repeatedly through our lives. I guess it doesn't cause cancer like HPV though.
Mods, if this is too off-topic, please feel free to move it. Wall of text incoming:
Well, the herpes viral family is pretty vast and complex. Most people are carriers of some members of the herpes family without even knowing it. Herpes viruses are very good at establishing latent infections in people (making it very difficult to target with the immune system) and also using a variety of viral proteins to help subvert and circumvent other immune surveillance. The herpes family includes some very common viruses - Herpes Simplex I and II (oral and genital ulcers and potential neurological disease), Varicella Zoster (chickenpox and shingles), cytomegalovirus aka CMV (congenital defects, neurological disease and mononucleosis), Epstein-Barr virus aka EBV (mononucleosis, Burkitt's lymphoma, nasopharengeal carcinoma).
Just about any herpes infection can result in becoming a carrier, and most people are infected/carriers with CMV and EBV and some of the other lesser known herpes viruses. In my field of immunology, researchers are trying to decipher why some herpes viruses sometimes cause disease in some otherwise healthy people (why doesn't the immune system just wipe the virus out), what causes their latent infections and the mechanisms of latency and re-activation as well as detection of latent viruses, and some work on vaccines, which seems to be very complicated in herpes viruses. Coincidentally, latent viruses don't seem to boost the immune system, thus don't aid in long-term immune memory.
However, both chickenpox and shingles have vaccines available. If you have never had chickenpox, you can get that and won't have to worry about the disease becoming latent and getting shingles later in life. However, if you have had chickenpox, you can still get a shingles vaccine (usually recommended after 60 years old) which can cut down your chances of getting shingles by about 65-70%. The targeted virus is the same, but my best guess is the exact vaccine differs in how the immune system responds to it, with the chickenpox vaccine eliciting more of a humoral response, and the shingles vaccine more of a cell-mediated response.
Epstein-Barr virus, most commonly known for causing mononucleosis, can also cause cancer. However, like all herpes viruses, it can establish latent infections and the prevalence of cancer is not the dominant effect of an infection, since about 95% of the population becomes infected during their lifetime, and Burkitt's lymphoma is not common in industrialized countries. I don't want to get into the politics of vaccines, but Burkitt's lymphoma is more common in equatorial Africa, where malaria is also dominant (malaria is thought to reduce resistance to Epstein-Barr virus). Of your original post though, Herpes Simplex I and II do not cause cancer. There is a phase III clinical trial in the United States for a Herpes Simplex II vaccine, called Herpevac, which seems to prevent the disease in some women (about 70-80%), but has not been shown to be effective in men.
Tricky things, those herpes viruses.
