The vaccination protects a person from future infection by the HPV high-risk types that can lead to cancer. It is not a vaccine against cancer itself. A person receives a series of three shots over a 6-month period. Health professionals inject these virus-like particles into muscle tissue. Once inside, these particles trigger a strong immune response, so the vaccinated person's body makes and stockpiles antibodies that can recognize and attack the L1 protein on the surface of HPV viruses.