Both hepatitis B vaccine and one of the human papillomavirus HPV vaccines (Gardasil) contain yeast proteins. These vaccines are made by inserting the gene that makes one viral surface protein into a plasmid (small circular pieces of DNA) and putting the plasmid into baker's yeast. When the yeast cells grow, they also make the viral proteins that eventually become the vaccine. Hep. B and HPV vaccines contain between one and five milligrams (thousandths of a gram of yeast proteins. Two HPV vaccines are available: Gardasil-This vaccine was first made available in June 2006. It contains proteins from four common HPV types: 6, 11, 16, and 18. Types 16 and 18 cause 70 of 100 cases of cervical cancer, and types 6 and 11 cause 90 of 100 cases of anal and genital warts. If anyone has a severe reaction to this immunization, then they should not get any more. However, when asking how scientists know who should get it, the answer can be found when doctors look under the microscope of pap smears. Most women infected with HPV rid themselves of it, but in some, the virus continues to infect cells of the cervix, causing pre-cancerous and then cancerous changes. All women who pass through three stages of cervical infection will get cervical cancer. HPV vaccine has been clearly shown to prevent this. In 2009 the FDA licensed the Gardasin vaccine for boys and men between 9 and 26 years of age. It was based on studies that showed it to be effective in preventing anal and genital warts. Unfortunately, the Advisory Committee on Immunization Practices did not fully recommend the vaccine, instead giving it a permissive recommendation, meaning people can use it if they want. Unfortunate, because now insurance companies may not pay for the vaccine for boys. And it will be harder to prevent anal and genital warts and cancers in men, and to lessen transmission of HPV from men to women.
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