EXECUTIVE SUMMARY

New evidence has been published to support the CDC’s recent recommendation for a two-dose human papillomavirus (HPV) vaccine to prevent genital warts.

  • Investigators studied nearly 400,000 U.S. females 9-18 years of age to find the rate of genital warts based on the number of vaccine doses received. The analysis indicated that receiving two or three doses of the vaccine was effective. Both provided significantly more protection against genital warts than one or zero doses.
  • The CDC recommends that girls and boys 11-12 years of age receive two doses of HPV vaccine at least six months apart, rather than the previously recommended three doses.

Investigators have published clinical evidence that supports the CDC’s recent recommendation for a two-dose human papillomavirus (HPV) vaccine to prevent genital warts, showing that the two-dose vaccine provides the same level of protection as three doses.1

Researchers studied nearly 400,000 U.S. females 9-18 years of age to find the rate of genital warts based on the number of vaccine doses received. Their analysis indicated that receiving two or three doses of the vaccine was effective. Both provided much more protection than receiving one or zero doses.1

The CDC recommends patients 11-12 years of age receive two doses of HPV vaccine at least six months apart, rather than the previously recommended three doses. Those who start the series at 15-26 years of age will continue to need three doses of HPV vaccine to protect against cancer-causing HPV infection. The recommendation was issued shortly after the FDA approved the addition of a two-dose schedule for the nine-valent HPV vaccine (Gardasil 9) for adolescents 9-14 years of age age in October 2016. (For more information, please visit: http://bit.ly/2li1dma.)

Researchers, led by Rebecca Perkins, MD, an obstetrician at Boston Medical Center and the study’s lead author, concluded that prospective effectiveness studies of recommended two-dose schedules against clinical endpoints such as persistent infection, genital warts, and cervical dysplasia are necessary to ensure long-term protection of vaccinated patients.

Although the data supporting a two-dose schedule is encouraging, the research focused only on genital warts, not cancer outcomes or cervical dysplasia. It’s crucial for other researchers to collect such data, according to Perkins, who also is an associate professor of obstetrics and gynecology at Boston University School of Medicine.

“This study will be a stepping stone for future research into the effectiveness of the two-dose schedule of the HPV vaccine for other symptoms of the disease,” Perkins said in a statement accompanying the publication.

Vaccine Effect on Oral HPV

New data have emerged, suggesting vaccine efficacy against oral HPV infections.2 The findings were presented at the American Society of Clinical Oncology’s June 2017 annual meeting in Chicago.

Maura Gillison, MD, PhD, professor at the University of Texas MD Anderson Cancer Center, and her team analyzed data collected between 2011 and 2014 in the National Health and Nutrition Examination Survey (NHANES), which was designed to assess the health and wellness of Americans.

In 2011, NHANES participants began self-reporting if they had received one or more HPV vaccines. Researchers studied responses from more than 2,600 young adults 18-33 years of age, comparing the prevalence of an oral HPV infection in those who received one or more doses of the vaccine to those who did not. At that time, about 18.3 percent of young adults in the U.S. reported receiving one or more vaccine dose by age 26, with vaccination more common in women than men (29.2% vs. 6.9%).1

The findings indicate that the prevalence (population-weighted) of oral HPV16/18/6/11 infections was significantly reduced in vaccinated vs. unvaccinated individuals (0.11% vs. 1.61%; P = 0.008), corresponding to an estimated 88.2% (95% confidence interval, 5.7-98.5%) reduction in prevalence.

The analysis suggests that oral HPV16/18/6/11 prevalence was reduced significantly in vaccinated vs. unvaccinated men (0.0% vs. 2.13%; P = 0.007). In contrast, prevalence for 33 non-vaccine HPV types was similar (3.98% vs. 4.74%; P = 0.24). Accounting for HPV vaccine-uptake, the population-level effectiveness of HPV vaccination on the burden of oral HPV16/18/6/11 infections was 17.0% overall, 25.0% in women and 6.9% in men.1

Previously, researchers found that HPV is responsible for several cancer types in men and women, including cancers in the oropharynx. It is estimated HPV is linked with approximately 70% of oropharyngeal cancers.3

According to Gillison, no one has conducted clinical trials that have prospectively evaluated whether the existing FDA-approved HPV vaccines will prevent oral infections that lead to the disease. Therefore, the vaccine is not approved for the prevention for head and neck cancers; it is approved for the prevention of cervical, vulvar, vaginal, and anal cancers in women and anal cancers in men.

“We don’t know if there’s a potential solution to these rising rates already existing on the shelves,” Gillison said in a statement accompanying the presentation. “In the absence of that gold standard clinical trial, we looked at data from a study that we’ve been conducting in my lab to address the question as to whether or not existing HPV vaccines could be altering oral HPV infections in the U.S. population.”

REFERENCES

  1. Perkins RB, Lin M, Wallington SF, Hanchate A. Impact of number of human papillomavirus vaccine doses on genital warts diagnoses among a national cohort of U.S. adolescents. Sex Transm Dis 2017;44:365-370.
  2. Gillison ML, Broutian T, Graubard B, et al. Impact of prophylactic human papillomavirus (HPV) vaccination on oral HPV infections among young adults in the U.S. Presented at the 2017 Annual Meeting of the American Society of Clinical Oncology. Chicago; June 2017.
  3. Chaturvedi AK, Engels EA, Pfeiffer RM, et al. Human papillomavirus and rising oropharyngeal cancer incidence in the United States. J Clin Oncol 2011;29:4294-4301.