In 2006, United States pharmaceutical company Merck released the Gardasil vaccination series, which protected recipients against four strains of Human Papillomaviruses, or HPV. HPV is a sexually transmitted infection which may be asymptomatic or cause symptoms such as genital warts, and is linked to cervical, vaginal, vulvar, anal, penile, head, neck, and face cancers. In 2006, based on research conducted by researchers Ian Frazer and Jian Zhou in the 1990s, Merck released a four-strain version of Gardasil, which protected boys and girls aged nine and older against the major HPV strains HPV-6, HPV-11, HPV-16, and HPV-18. In 2014, Merck released Gardasil 9, a nine-strain version that protected from the original four HPV strains plus strains HPV-31, HPV-33, HPV-45, and HPV-58. Gardasil is a preventative measure and reduces the risk of contracting HPV and HPV-related cancers by up to ninety-seven percent.

On 20 August 2007, in Frazer v. Schlegel, the United States Court of Appeals for the Federal Circuit decided that researchers Ian Frazer and Jian Zhou owned the rights to the vaccine patent for Human Papillomavirus, or HPV, instead of a research team led by Richard Schlegel. Frazer v. Schlegel reversed the decision that the Board of Patent Appeals and Interferences had previously made, awarding the patent to Schlegel on the basis that Frazer’s patent application contained inaccurate science. However, once appealed, the Federal Circuit judges found Frazer’s science to be accurate, granting him rights to the vaccine patent. In 2006, the US Food and Drug Administration, or FDA, approved the first HPV vaccine, which has since been effective in protecting women from cervical cancer by up to ninety-seven percent if they were vaccinated before contracting HPV. The Circuit’s decision gave Frazer ownership of the patent for the HPV vaccine, which physicians have administered over 120 million doses of to people in the US.

The Human Papillomavirus (HPV) strains 16 and 18 are the two most common HPV strains that lead to cases of genital cancer. HPV is the most commonly sexually transmitted disease, resulting in more than fourteen million cases per year in the United States alone. When left untreated, HPV leads to high risks of cervical, vaginal, vulvar, anal, and penile cancers. In 1983 and 1984 in Germany, physician Harald zur Hausen found that two HPV strains, HPV-16 and HPV-18, caused cervical cancer in women. In the early twenty first century, pharmaceutical companies Merck & Co. and GlaxoSmithKline created HPV vaccines protecting against HPV-16 and HPV-18, which have reduced the number of HPV infections by fifty-six percent in the US. Discovering HPV strains 16 and 18 allowed physicians to test for those cancer-causing cell populations using Pap smears, a diagnostic tool that collects cells from the woman's cervix to identify cancerous cases of HPV infection. By identifying the cancerous strains of HPV-16 and HPV-18 and utilizing preventative measures such as the Pap smear and HPV vaccines, the rates of cervical cancer and other HPV-related cancers have reduced.