The Auckland Sexual Health Service says the rate of young women presenting with genital warts has more than halved in the past three years.
It says the drop occurred after the introduction of the anti-cervical cancer vaccine Gardasil.
The vaccine, designed to protect against strains of the human papilloma virus linked with cervical cancer and genital warts, is free for girls aged 12 to 18.
The Auckland Sexual Health Service says that in 2007 nearly 14% of the women under 20 it saw had genital warts. That rate, it says, has been cut to 5%.
The service's lead researcher, Dr Jeannie Oliphant, says the results are incredibly exciting, and the first indication that Gardasil is working.
