Most of HPV infections have a long-term clinical course asymptomatically. In the past, it was thought that once HPV enters the body, it could never be cleared off the body and would become chronic. Contrary to popular belief, 60-70% of HPV infections are cleared off the body by the immune system within 1 year, and 70% within 2 years. It is very important to have a strong immune system for the elimination of HPV from the body. A weak immune system is the biggest obstacle to the eradication of the virus from the body Since the virus does not get into the blood stream, there is no strong systemic immune response, and the virus is mostly cleared off body by regional immune mechanisms. The virus that cannot be eliminated from the body may cause cancer precursor lesions in the following years.