have been created. The hepatitis B vaccine is the first vaccine that has been established to prevent cancer (hepatocellular carcinoma) by preventing infection with the causative virus. In 2006, the U.S. Food and Drug Administration approved a human papilloma virus vaccine, called Gardasil. The vaccine protects against four HPV types, which together cause 70% of cervical cancers and 90% of genital warts. In March 2007, the US Centers for Disease Control and Prevention (CDC) Advisory Committee on Immunization Practices (ACIP) officially recommended that females aged 11–12 receive the vaccine, and indicated that females as young as age 9 and as old as age 26 are also candidates for immunization. History The history of cancer virus discovery is intertwined with the History of cancer research and the history of virology. The oldest surviving record of a human cancer is the Babylonian Code of Hammurabi (dated ca. 1754 BC) but scientific oncology could only emerge in the 19th century, when tumors were studied at microscopic level with the help of the compound microscope and achromatic lenses. 19th century microbiology accumulated evidence that implicated bacteria, yeasts, fungi, and protozoa in the development of cancer. In 1926 the Nobel Prize was awarded for documenting that a nematode worm could provoke stomach cancer in rats. But it was not recognized that cancer could have infectious origins until much later as virus had first been discovered by Dmitri Ivanovsky and Martinus Beijerinck at the close of the 19th century. History of non-human oncoviruses The theory that cancer could be caused by a virus began with the experiments of Oluf Bang and Vilhelm Ellerman in 1908 at the University of Copenhagen. Bang and Ellerman demonstrated that avian sarcoma leukosis virus could be transmitted between chickens after cell-free filtration and subsequently cause leukemia. This was subsequently confirmed for solid tumors in chickens in 1910–1911 by Peyton Rous. Rous at the Rockefeller University extended Bang and Ellerman's experiments to show cell-free transmission of a solid tumor sarcoma to chickens (now known as Rous sarcoma). The reasons why chickens are so receptive to such transmission may involve unusual characteristics of stability or instability as they relate to endogenous retroviruses. Charlotte Friend confirmed Bang and Ellerman findings for liquid tumor in mice by . In 1933 Richard Shope and Edward Weston Hurst showed that warts from wild cottontail rabbits contained the Shope papilloma virus. In 1936 John Joseph Bittner identified the