Dramatic Decline in Female Genital Warts Following HPV Vaccination

The introduction of the Australian national human papillomavirus (HPV) vaccination program has resulted in a significant reduction of genital wart prevalence among young women.

Researchers at the University of Sydney (NSW, Australia) conducted an analysis of 1,175,879 patient encounters with 11,780 general practitioners (GPs). Genital warts management rates were estimated for the periods before and after introduction of the program (pre-program, July 2002-June 2006; post-program, July 2008-June 2012). Control conditions included genital herpes and Gardnerella/bacterial vaginosis in female patients, and genital herpes and urethritis in male patients. Trends in management rates by year were also calculated.

The researchers found that the management rate of genital warts among women potentially covered by the program (i.e., ages 15–27 years) decreased by 61%, from 4.33 per 1,000 encounters in the pre-program period to 1.67 in the post-program period. Trend analysis showed a significant year-on-year reduction in the rate of genital warts management post-vaccination, and a significant increase in the management rate of control conditions per year. For all other age-sex groups there was no significant change in the management rate of genital warts between the pre- and post-program periods. The study was published in the September 2014 issue of PLOS One.

“The results show that the program has been a widespread success. Not only do genital warts cause distress in affected patients, but treatment is at a substantial cost to the health system,” said lead author Christopher Harrison, MSc, of the University of Sydney Family Medicine Research Centre (FMRC). “There was also no significant decrease in other sexually transmitted infections over this period, which means that the decrease in genital warts was likely due to the vaccination program, not a change in the women's behavior.”

Australia was one of the first countries to provide the HPV vaccine free to young women through a national immunization program. The program was initially promoted in terms of prevention of cervical cancer, as HPV types 16 and 18 are known to be the major etiological agents to cervical cancer in around 70% of cases worldwide. However, the quadrivalent vaccine also protects against HPV types 6 and 11, the major causes of genital warts.

Related Links:
University of Sydney