Is Gardasil® Recommended for Young Women Already Exposed to HPV?

From Medscape Pharmacists
Ask the Experts about Pharmacotherapy
Posted 04/01/2009
Laurie L. Briceland, PharmDAuthor Information

Should Gardasil® (human papillomavirus [HPV] quadrivalent [types 6, 11, 16, and 18] vaccine) be administered to young women who test positive for oncogenic-risk HPV strains, or to those who have abnormal Papanicolaou ("Pap") smear results?

Response from Laurie L. Briceland, PharmDProfessor and Director, Experiential Education, Department of Pharmacy Practice, Albany College of Pharmacy, Albany, New York

Genital human papillomavirus (HPV) is the most common sexually transmitted infection in the United States, with an estimated 20 million people already infected and over 6 million people infected annually.[1]

Although most infections prove to be self-limiting or asymptomatic, persistent infection with oncogenic strains (such as types 16 and 18) can lead to cervical cancer.
Seventy percent of cervical cancers are attributed to HPV types 16 and 18; HPV types 6 and 11 contribute to 90% of cases of genital warts.[2]

The HPV quadrivalent (types 6, 11, 16, and 18) vaccine (Gardasil®) was approved by the US Food and Drug Administration in 2006 and is indicated for use in 9- to 26-year-old females for the prevention of diseases caused by those 4 virus strains.
These diseases include cervical, vulvar, and vaginal cancer caused by HPV types 16 and 18; cervical, vaginal, and vulvar cancer precursor and dysplastic lesions; and genital warts caused by HPV types 6 and 11.[3]
Clinical trials indicate that the vaccine is effective in preventing HPV infection and precancerous lesions in females who have not already been infected with the respective HPV type.[2]
Thus, the goal is to administer the vaccine series to females prior to their sexual activity debut, with the recommended age being 11-12 years.[2]

Vaccination is also recommended for 13- to 26-year-old females who have not been vaccinated, or who have not completed the vaccination series, even if the female is already sexually active and could have contracted HPV infection.
No evidence exists of protection against vaccine HPV types that have already infected the female at the time of vaccination.
However, females infected with fewer than all 4 of the vaccine HPV types before vaccination would likely receive protection and partial benefit against the other vaccine types upon vaccination.[2]
Vaccination is recommended for females with an abnormal Pap test in order to impart partial benefit from vaccine type(s) to which the female has not already been infected.
As Pap test results increase in severity, risk for infection with HPV 16 or 18 increases, potentially decreasing the benefit of vaccination.[2]

Patients should be counseled that the vaccine will not have any therapeutic benefit on existing HPV infection or lesions based on clinical trial data.[2]
It is important to note that patients who receive Gardasil® should continue to undergo routine cervical cancer screenings by Pap test as recommended by their physicians.[2,3]