HPV vaccine and its recommendations, 2007.(Human papillomavirus)

Quadrivalent human papillomavirus vaccine against the viral types most likely to cause cervical cancer (types 16 and 18) and genital warts (types 6 and 11) has been licensed in the United States. The vaccine is 95% to 100% efficacious against cervical intraepithelial neoplasia and adenocarcinoma in situ and 99% efficacious against genital warts caused by serotypes in the vaccine. Local pain injection site pain and swelling are the main adverse reactions. Routine vaccination of females at 11 to 12 years of age is recommended. Catch-up vaccination is recommended for females age 13 to 26 years who have not yet been vaccinated, and vaccination of girls 9 and 10 years of age is permitted at the discretion of the physician.

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Human papillomavirus (HPV) is the most common sexually transmitted infection (STI) in the United States, with 20 million individuals currently infected with HPV and 6.2 million new cases each year. (1) Although most HPV infections are self-limited, HPV infection that persists for years to decades can cause cervical, vulvar, vaginal, penile, and anal cancer, as well as genital warts (condylomata acuminata).

Cervical Cancer

The American Cancer Society estimated the number of new cervical cancer cases during 2006 to be 9710, with 3700 deaths due to cervical cancer. (2) The estimated lifetime cervical cancer risk is 3.67%, and the lifetime cervical cancer mortality risk is 1.26%. (3) The main cause of cervical cancer is HPV infection (CENTERFOLD, FIGURE 1). Molecular studies show that HPV DNA is present in almost all (99.7%) cervical cancers, (4,5) with HPV type 16 responsible for 50.5% of cases and type 18 for 13.1% of cases. (6)

Cervical cancer prevention entails both primary and secondary prevention approaches. Primary prevention measures include sexual practices that limit exposure to HPV (eg, lifelong monogamy and use of condoms) and HPV vaccination. Secondary prevention efforts include cervical cytology and HPV screening as well as removal of HPV-infected precancerous lesions.

HPV Epidemiology and Natural History

HPV is a group of almost 200 viruses, which can be classified as high oncogenic risk and low-risk based on their type. Of these, 15 high-risk types, particularly HPV types 16 and 18, have been associated with cervical cancer. Viral proteins E6 and E7--which prolong cell replication--promote genomic instability and progression to cancer. Low-risk HPV types, especially types 6 and 11, are associated with genital warts and laryngeal papillomas.

Exposure to HPV within a few years of sexual debut is common but not universal. In one study of female college students, 39% were infected with HPV within 24 months of sexual debut, rising to about 54% infected with HPV by 48 months. (7) The most common individual HPV types for first infection were high-risk types 16 and 56 and low-risk type 6. An estimated 80% of sexually active persons have been infected with at least 1 HPV serotype by age 50 years. Among virgins, nonpenetrative sexual contact (eg, finger-vulvar or oral-penile) has been associated with an increased risk of HPV. (7) Prevalence of HPV infection is highest among females age 20 to 24 years. In one study, the percentage of adolescent females reporting a history of sexual activity was 29% among 9th graders, 39% among 10th graders, 50% among 11th graders, and 60% among 12th graders. (8)

In most cases, HPV infections are asymptomatic and transient. About 70% of new HPV infections clear within 1 year and about 91% clear within 2 years (9,10);…