New vaccine effective for 9 HPV strains

A new 9-valent vaccine to prevent human papillomavirus (HPV) has shown nearly 100% efficacy against 5 additional strains of the virus when compared with quadrivalent HPV vaccine, and it is now recommended for routine vaccination by the Centers for Disease Control and Prevention’s Advisory Committee on Immunization Practices (ACIP).

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The New England Journal of Medicine reports that in a randomized, controlled trial of 14,000 girls and young women aged 16 through 26 years, the 9-valent vaccine was shown to have nearly 100% efficacy against HPV strains 31, 33, 45, 52, and 58 (associated with cervical, vulvar, and vaginal disease) in addition to protection against the 4 types (HPV 6, 11, 16, and 18) contained in the quadrivalent HPV vaccine.

Human papillomavirus is associated with cervical, vulvar, and vaginal cancer in girls and women; penile cancer in boys and men; and anal and oropharyngeal cancers in both males and females. The majority of all HPV-associated cancers (70%) are caused by HPV 16 or 18, the 2 types targeted by 2-valent, quadrivalent, and 9-valent HPV vaccines. In the United States, approximately 64% of invasive HPV-associated cancers are caused by HPV 16 or 18, and about 10% are attributable to the 5 additional types in the 9-valent vaccine.

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The ACIP HPV Vaccine Work Group reviewed clinical trial data on the efficacy, immunogenicity, and safety of the 9-valent HPV vaccine versus quadrivalent HPV vaccine before updating the recommendation. Analyzing a phase III efficacy trial, the Work Group reported that in the 9-valent group of trial participants, more than 99% seroconverted to all 9 vaccine types 1 month after receiving 3 doses. In 1 immunobridging trial, more than 99% of trial participants seroconverted to all 9 HPV vaccine types, and in another, 100% of participants seroconverted to HPV 6, 11, 16, and 18. Safety profiles were similar in both quadrivalent and 9-valent HPV vaccines, with most adverse events being mild-to-moderate injection-site pain, swelling, and erythema.

The HPV vaccine is recommended for children aged 11 or 12 years, or as young as age 9 years, and for both young women aged 13 through 26 years and young men aged 13 through 21 years who have not been vaccinated previously or who have not completed the 3-dose series. After the initial dose, the second dose is administered at least 1 to 2 months later, followed by the 3rd dose at least 6 months after the initial dose. If the vaccination series is interrupted, there is no need to restart. The HPV vaccines are not recommended for pregnant women, but if a dose has inadvertently been administered during pregnancy, no intervention is needed.

In a recent editorial, Anne Schuchat, MD, the US assistant surgeon general, noted that HPV vaccine coverage in the United States remains “a problem.” Coverage for the first dose of the series among girls aged 13 to 17 years is 57%, trailing coverage for other recommended childhood vaccines by 20% to 25%. She says that if enough adolescents were offered the first dose of HPV vaccine and accepted subsequent doses each time they received another vaccine, first-dose coverage for HPV vaccine would surpass 90%. Currently, 4 of 10 girls have not even begun the HPV vaccine series.

More: Dr Schuchat discusses the decline HPV vaccination rate in teenagers

“Even with the availability of another HPV vaccine targeting additional cancer-causing virus types, 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,” she writes.

Because a 3-dose schedule for HPV vaccine can be intimidating to parents of teenagers and their healthcare providers, an ongoing clinical trial is testing a 2-dose schedule for the 9-valent HPV vaccine as well as the immunogenicity of alternative scheduling, and ACIP will review the results as data becomes available.