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Study Finds Nine-Strain HPV Vaccine Highly Effective

Study Finds Nine-Strain HPV Vaccine Highly Effective

February 20, 2015 — A vaccine that targets nine human papillomavirus strains that are known to cause cancer was highly effective at preventing disease, according to a study published Thursday in the New England Journal of Medicine, MedPage Today's "The Gupta Guide" reports (Smith, "The Gupta Guide," MedPage Today, 2/18).

Vaccine Details

FDA approved the new vaccine, Merck's Gardasil 9, in December 2014. The original HPV vaccine, Gardasil, protects against four HPV strains, including two types linked to roughly 70% of all cervical cancer cases, while the new vaccine protects against five additional strains. These nine strains account for about 90% of cervical cancer cases (Women's Health Policy Report, 12/11/14).

Study Details

Researchers conducted a randomized, controlled noninferiority trial comparing the effectiveness of the updated and original HPV vaccines in 14,215 women ("The Gupta Guide," MedPage Today, 2/18). The women were ages 16 to 26 and lived in Australia, Austria, Brazil, Canada, Colombia, Denmark, England, Germany, Hong Kong, Norway, Taiwan or the U.S. For each participant, researchers analyzed 10 Pap tests and genital swabs over four and a half years for DNA evidence of 14 HPV strains (Kaplan, "Science Now," Los Angeles Times, 2/18).

According to the study, the updated vaccine was 96.7% effective at preventing high-grade cervical, vaginal or vulvar disease linked to the five additional HPV strains it targets. In addition, the newer vaccine was equally effective as the original against disease caused by the four other HPV stains ("The Gupta Guide," MedPage Today, 2/18).

Specifically, 14 cases of cervical, vulvar and vaginal diseases occurred per 1,000 individuals in each group. However, new cases of HPV were 43% lower in the group that received the nine-valent vaccine. Overall, the study found that the newer vaccine was 100% effective at protecting against the nine targeted strains of HPV, and it reduced the risk of contracting other types of HPV by 20%.

CDC Official Calls Findings 'Milestone' for Coverage

Anne Schuchat, director of CDC's National Center for Immunization and Respiratory Diseases, called the study a "milestone in expanding the coverage of cancers associated with" HPV ("Science Now," Los Angeles Times, 2/18).

However, she noted in an accompanying editorial that "four of 10 adolescent girls have not even begun HPV vaccination," which could be due in part to the expense of the vaccine, even for those with insurance coverage, and the need to make three office visits to complete the vaccination series.

Schuchat wrote, "Vaccination of a much higher proportion of preteens is needed. Otherwise, decades from now oncologists will still be talking about HPV-associated cancers with thousands of new patients every year" ("The Gupta Guide," MedPage Today, 2/18).