IMMUNIZATIONS – SPECIFIC VACCINES
Human Papillomavirus (HPV)
Human Papillomavirus (HPV) is a sexually transmitted viral illness that causes genital warts and cervical cancer. In the United States, more than 20 million people were infected with the virus in 2005, and more than 50% of sexually active people contract the disease during their lifetime. There are more than 100 different strains of the virus, but only seventeen of these have been shown to put people at higher risk for cancer and genital warts. Strains 16 and 18 are found in 50-80% of pre-cancerous lesions, and up to 90% of invasive cervical cancer. These strains along with types 6 and 11 are responsible for more than 90% of genital wart cases.
HPV is a “silent” virus, which means that until you develop genital warts or cervical cancer, you are unaware of the infection. Most people who are infected with HPV clear the infection on their own within a few months to a few years. Only a small percentage of infected women develop cervical cancer. Several factors that increase a woman’s risk of developing HPV-related cervical cancer are: early age at menarche (first period), early age at first intercourse, high number of sexual partners, and a high-risk strain of HPV.
In the US, there are more than 10 thousand new cases of cervical cancer each year, and cervical cancer leads to more than 3500 deaths per year. Women are screened for cervical cancer on Pap smears, but this often reveals late-stage cervical changes. Furthermore, adolescents and young women often avoid getting gynecologic examinations and Pap smears, prolonging the time between infection and diagnosis. Over the last few decades there has been a decline in the rate of advanced stage cervical cancer due to mass screening and early treatment of pre-cancerous lesions, but it is still a serious health concern.
Gardasil is a vaccine against the 4 strains of HPV that cause the most cervical cancer and genital warts (types 6, 11, 16, and 18). It is made of proteins from the virus, but not the virus itself, so it does not cause HPV infection. It is yeast-based, so people with an allergy to yeast, or those who have had a reaction to yeast-based vaccines in the past should not receive the injection.
Gardasil is most effective if given to pre-pubertal girls, as they are also unlikely to be sexually active. It can, however, be given to girls and women who have already been sexually active, and will protect against strains to which they have not yet been exposed. Although Gardasil prevents cervical cancer and genital warts from the 4 strains of virus contained in the vaccine, it does not protect against any of the other 95 strains. There is still a risk of non-vaccine HPV disease, and women who have been vaccinated still need to undergo regular Pap smears and gynecologic screening.
Gardasil is also available to boys & men. Although they can not get cervical cancer, the vaccine will still prevent genital warts & the likelihood of a male spreading the virus to a female.
The side effects of the vaccine are similar to other injected vaccines. There is a slightly increased risk of autoimmune disorders including lupus and rheumatoid arthritis, but for every new case of these disorders, 8 cases of cervical cancer were prevented.