HPV Vaccination Sends Genital Wart Cases Plummeting: Study

Australian effort saw nationwide rates drop up to 93 percent in girls, young women.

By Alan Mozes
HealthDay Reporter

THURSDAY, April 18 (HealthDay News) -- In the five years since launching a nationwide human papillomavirus (HPV) vaccination program among girls between the ages of 12 and 26, Australia has seen a huge drop in the number of cases of genital warts, new research reveals.

Among Australian girls in the targeted age range for vaccination, the country saw genital wart cases plummet by 59 percent within just the first two years of the program's launch in 2007.

By aggressively vaccinating girls against HPV (which is responsible for 90 percent of genital wart diagnoses), Australia appears to have offered considerable protection not just to its female population but also its men as well.

How? Researchers point to a phenomenon known as "herd immunity," whereby the immunity acquired by a certain segment of the population -- in this case, women -- ends up protecting an unvaccinated segment of the population (men).

In the same timeframe Australia has seen a 39 percent drop in genital wart cases among heterosexual men as well.

"All indications are that the program has been an overwhelming success," noted study author Dr. Basil Donovan, who heads the sexual health program at the Kirby Institute of the University of New South Wales, in Sydney.

"But we won't be certain until HPV-related cancers [also] start dropping," he added, explaining that while genital warts tend to appear roughly three months following infection with HPV, "the incubation period from HPV infection to HPV-related cancer is typically at least 20 to 30 years."

HPV-associated cancers include cervical, penile, anal and throat cancers, according to the U.S. Centers for Disease Control and Prevention.

Donovan and his colleagues published their findings in the April 18 issue of the BMJ.

To explore the impact of HPV immunization efforts in the Australian context, the authors analyzed data collected from eight different sexual health service organizations covering a period from 2004 to 2011.

Collectively, the organizations had seen nearly 86,000 first-time patients in that timeframe, of whom about 9 percent were diagnosed with genital warts.

By comparing the pre-vaccination period of 2004 to mid-2007 with the vaccination period of mid-2007 through the end of 2011, the team found a remarkable plunge in genital wart rates.

Among girls under the age of 21, that drop amounted to nearly 93 percent, while among those between 21 and 30 a decline of almost 73 percent was observed.