Australia is on track to eliminate genital warts, thanks to a world leading vaccination program to tackle human papillomaviruses (HPVs), say experts presenting at the Australasian Sexual Health Conference in Darwin.
The program is expected to also slash rates of cervical and other genital and throat cancers, and was recently expanded to include school-age boys – the first and only country in the world to do so. Statistics released on Monday show rates of genital warts in women and heterosexual men are already decreasing.
'Vaccination against human papilloma virus in Australia has been extremely successful, decreasing rates of genital warts in women and heterosexual men," says Associate Professor David Wilson of The Kirby Institute, University of New South Wales.
Australia began its HPV vaccination for women and girls in 2007. The ongoing programme offers free vaccination to girls aged 12-13 years in schools. In addition, from 2007 to 2009 two catch-up programmes were implemented"one for 13-18 year old school girls and the other for 18-26 year old women in the community.
The vaccine has now been offered to boys aged 12-13 years, with a catch-up program includes boys aged 14-15. The USA recommends vaccination for 12-15 year old boys but does not pay for it as part of a public health program.
In research presented at the conference, Assoc Prof Wilson's colleagues at the Kirby Institute, Professor Basil Donovan, Dr Hammad Ali and their co-authors compared trends in proportion of patients diagnosed with genital warts in the pre-vaccination (2004 to mid-2007) and vaccination (mid-2007 to 2012) periods across 8 Australian sexual health clinics.
The results show that, in the pre-vaccination period, there was no change in proportion of men diagnosed with genital warts. In the vaccination period, there were significant declines in proportions of heterosexual men aged under 21 years (88%, compared to 90% decline in women of the same age) and 21-30 year old men (58%, compared to 72% in women of the same age) diagnosed with genital warts. The absolute declines in incidence in men diagnosed with genital warts under 21 years were from 12.1% in 2007 to 1.5% in 2012, and in men aged 21-30 years from 18.2% in 2007 to 7.7% in 2012 respectively.
There was no significant decline in diagnosis of genital warts in men >30 years of age, or in homosexual or bisexual men"this is because the programme initially targeted only women and girls. In around five years, when the first cohort of boys reaches age 17-18 years and becomes sexually active, a benefit in all of them, including those who are gay or bisexual, can be expected," says Professor Donovan.
Dr Ali adds: 'With the introduction of male vaccination program, the model predicts a much lower incidence, approaching elimination in both males and females, in coming decades."
Assoc Prof Wilson adds: 'These results speak to the resounding success of the HPV vaccination program in Australia," said A/Professor Wilson. 'Heterosexual men seem to be benefiting from the vaccine through a phenomenon known as herd immunity, resulting from high coverage in the young women who are their sexual partners, and we can expect even better results since the vaccination program has now been rolled out for boys."
Due to the extended period of time it takes for cervical cancer to develop, it remains too early to determine the effect of the programme on cervical cancer in women or other cancers causes by HPV, such as throat and anal cancers in both sexes and cancers of the penis in men. However early published research has shown that the programme has reduced the lesions that can develop into cervical cancer in women.
'There is every reason to believe that what the vaccine has done for genital warts will eventually happen to most HPV-related cancers," concludes Prof Donovan.