The HPV vaccine prevents infection with the virus that is the cause of cervical cancer. It should be given to girls (typically around 11 years old). The vaccine is made up of one of the viral proteins that makes up the viral coat. When injected, the immune system responds by making antibodies to the protein that blocks any naturally acquired virus from infecting the body. It is recommended that two doses of the vaccine is given, however even one dose offers protection against infection with the HPV.
There are several different vaccines that have been developed. All vaccines protect against two or more of the ‘high-risk’, cancer-causing HPV types – in particular HPV16 and HPV18. The ‘second generation’ vaccines protect against nine HPV types. Vaccination against HPV16 and HPV18 alone is sufficient to prevent around 70% of cases of cervical cancer.
The cancer-causing high-risk HPV types are also associated with some head and neck cancers and a high proportion of anal cancer. Vaccination will also protect against those cancers.
The HPV vaccine is preventative. There is no strong evidence supporting it being effective in those who already have infection. Vaccinating early provides the best protection against cancer.