The vaccine against human papillomavirus (HPV) infections has been found to be more effective than expected. A study published in The Journal of Infectious Diseases stated that since the vaccine was introduced in 2006, the incidence of HPV has decreased 56% among all, vaccinated and unvaccinated, females aged 14 to 19, including those who had not been vaccinated. Amongst vaccinated females, HPV incidence decreased 88%. Introducing the vaccine at a younger age prevents the virus from being passed through other sexually active people later on in life and lowers the incidence of certain cancers of the whole population in the future.
HPV consists of a group of 150 viruses, of which 40 can be spread through direct skin-to-skin contact.
HPV itself is usually not dangerous, since around 75% of men and women have HPV infections during their lifetimes, most of which resolve themselves and do not cause cancer. However, a few HPV strains such as HPV types 16 and 18 cause nearly all cases of cervical cancer and anal cancer. HPV types 16 and 18 are also responsible for half of vaginal, vulvar, throat, and penile cancers, and have been also been linked to oral cancers. HPV infections cause 5% of all cancers worldwide. However, it is important to apply Bayesian reasoning and remember that most HPV infections do not cause cancer.
Because of the high rate of prevalence and general harmlessness of the infection, STD tests do not usually screen for HPV. Pap tests can be conducted for females to identify lesions and cytologic abnormalities that may result because of HPV and progress into cervical cancer if left untreated. There are currently no FDA-approved tests to detect HPV infections in men. There is also currently no medical treatment for HPV infections, but precancerous lesions can be exised in various ways, such as through freezing, surgical removal, or with lasers.
Since it would be commercially unviable to develop vaccines that protect against all strains of HPV, vaccines are developed to protect against a few strains that are linked to cancer.
However, only a third of girls 13-17 have taken the full three-stage vaccine against HPV. This may have been caused by parental fear that vaccinated against a sexually transmitted disease would promote promiscuity among teenagers. But along with showing the decrease in HPV incidence, the study also found that sexual behaviour did not vary significantly between groups of vaccinated and unvaccinated females.
The vaccine was introduced to 11 year old girls in 2006 and recommended for boys in 2011. Unfortunately there is no data as to how many boys have received the vaccine.
There are currently two HPV vaccines available: Gardasil and Cervarix. Gardasil is covered by the undergraduate university health plan, and offered in Health Services for male and female students. Gardasil protects against HPV types 17 and 18, responsible for 70% of cervical cancers, and HPV types 6 and 11, associated with 90% of genital warts.