What are the HPV vaccines?

Because of the seriousness of this problem, scientists spent a lot of time researching HPV. Finally, in 2006, the Food and Drug Administration (FDA) approved a much-anticipated HPV vaccine called Gardasil. This enormously important vaccine protects against four types of HPV—two that cause 90% of anogenital warts, and two that cause 70% of cervical cancers. It is important to note that there are more than 40 subtypes of genital HPV, so not all types are covered by the Gardasil vaccine. Gardasil is approved for both females and males from the ages of 9 through 26 years.

Another HPV vaccine was approved by the FDA in November 2009. This vaccine is called Cervarix and is approved for use in females aged 10 through 25 years. Cervarix is designed to protect against two types of HPV that cause cervical cancer. Both Gardasil and Cervarix consist of noninfectious, virus-like particles. In other words, you can't get HPV from receiving these vaccines. Gardasil and Cervarix are given by a series of three injections. The second shot is typically given 1 or 2 months after the first one, and the final shot is typically given 6 months after the first one. Past medical studies of Gardasil have demonstrated that it provides protection for 5 years. Ongoing studies are being conducted to determine if it actually provides protection for at least 14 years. Cervarix has been found to provide protection for 6 years.

What protection do the HPV vaccines provide?

Large scientific studies (one of them included more than 20,000 women between the ages of 16 and 26) have shown that women who were not previously exposed to HPV, and who completed the three-injection series of Gardasil, received virtually complete protection against the four types of HPV covered by the vaccine. Specifically, Gardasil provided protection against 99% of HPV 16-related lesions, 100% of HPV 18-related lesions, 99% of anogenital warts, and 100% of precancerous^[1] HPV 16- and 18-related vaginal and vulvar lesions.

Even in the patients who failed to complete the three-injection series or who were HPV-positive prior to the vaccine, there still was a sizeable reduction in HPV 16-and 18-related precancerous lesions. (It was a 42% and 81% decrease, respectively.) Moreover, it also has been recently discovered that Gardasil seems to provide cross-protection against other types of HPV that are not included in the vaccine. This positive development is the result of the similarity of proteins among the various types of HPV. Researchers are hopeful that this signals added protection for women against genital cancers.

Cervarix also provides protection against the two more common high-risk HPV types, HPV 16 and 18. The primary clinical study for Cervarix showed it was 93% effective in preventing precancerous cervical lesions caused by HPV 16 and 18 in females who had no prior known exposure to these HPV types.

Are the HPV vaccines recommended for adolescent girls?

The Advisory Committee on Immunization Practices (which consists of 15 experts on vaccine-preventable diseases who advise the Secretary of Health and Human Services and the CDC) recommends that the HPV vaccine should be administered to 11- and 12-year-old girls as part of a routine vaccination schedule. The American College of Obstetricians and Gynecologists, the Society for Adolescent Medicine, and the American Academy of Family Physicians have made similar recommendations.

When the HPV vaccination recommendations were first announced, there understandably was a lot of pushback from parents who initially felt that it was unnecessary to vaccinate their preteen-aged daughters against a sexually transmitted infection. However, as the word has gotten out that the whole point of the program is to inoculate children before they are exposed to HPV, the resistance has waned. Nevertheless, whenever it comes to vaccines—or any other type of medication or medical treatment—it is wise to become fully informed about them.

• [1] A condition in which there is the potential that a cancer will form. Precancerous cells on the cervix, if left untreated, may have the ability to form cervical cancer.