There are two vaccines available on the market and they protect against different types of HPV.
The Gardasil vaccine produced by Merck & Co. (Merck) is a quadrivalent vaccine because it protects against four HPV types: 6, 11, 16 and 18. Gardasil is given through a series of three injections into muscle tissue over a period of six months. The US Food and Drug Administration (FDA) has approved Gardasil for use in females for the prevention of cervical cancer, and some vulvar and vaginal cancers, caused by HPV types 16 and 18 and for use in males and females for the prevention of genital warts caused by HPV types 6 and 11.
Another vaccine, Cervarix by GlaxoSmithKline (GSK), is bivalent because it targets two HPV types: 16 and 18. This vaccine is also administered in three doses over a period of six months. Findings have shown that Cervarix also protects against persistent infection with HPV 16 and 18.
Neither of these vaccines have proved to provide complete protection again persistent infection with other HPV types some of which cause cervical cancer. About 30% of cervical cancers and 10% genital warts will not be prevented by these vaccines. Neither vaccine prevents other sexually transmitted diseases, and they do not treat HPV infection or cervical cancer.
Because the vaccines do not protect against all HPV infections that cause cervical cancer, it is important for vaccinated women to continue to undergo cervical cancer screening as recommended for women who have not been vaccinated. - (Health24, August 2011)
Source: National Cancer Institute