|HPV vaccination for women also benefits men. Image: jostrust|
A study of human papillomavirus (HPV) by Monash University researchers at the Melbourne Sexual Health Centre has found – for the first time – that HPV vaccination programs for women are also benefitting men.
Australia introduced a school-based quadrivalent vaccination program for HPV for girls in April 2007 targeting four genotypes of HPV: genotypes 6 and 11, which are responsible for genital warts and the high-risk genotypes 16 and 18 which can cause malignant cancers including ovarian, penile and anal cancers. Genital HPV, a common sexually transmitted infection, has many types.
It was already known that the program reduced rates of HPV infection in young women but the study marked the first time the effects on young heterosexual men were analysed.
Researchers led by Dr Eric Chow and centre director Professor Kit Fairley conducted a retrospective analysis of urine and urethral swab chlamydia positive specimens taken from heterosexual men aged 25 years or younger attending the centre from 2004 to 2015. They analysed data from a number of other HPV genotypes as well as the four targeted by the vaccines.
The results were striking: of the Australian-born men, the prevalence of the low-risk genotypes 6 and 11 dropped from 11% to 1%, whilst genotypes 16 and 18 dropped from 9% to 1%. The non-vaccine targeted genotypes considered increased from 16% to 18%.
Data was also conducted comparing Australian-born men with men in other countries that had bivalent vaccination programs for HPV genotypes 16 and 18, (England, Scotland, Wales, the Cook Islands, Northern Ireland and the Netherlands). The findings showed that prevalence of these genotypes in the post-vaccination period decreased significantly whilst the prevalence of non-vaccinated genotypes 6 and 11 didn’t.
The study, which appeared in the journal Lancet Infectious Diseases, noted that the trends were consistent with the magnitude in reduction in genital warts in men from previous findings but were the first evidence of what is called “herd protection” from the two high-risk genotypes.
Dr Chow said the clinic now sees far fewer cases of genital warts but that rates of cancer associated with HPV are harder to monitor because of the time it takes for cancer to develop.
HPV vaccination programs for boys began in Australia in 2013.
Reference: Chow EP, Machalek DA, Tabrizi SN, Danielewski JA, Fehler G, Bradshaw CS, Garland SM, Chen MY, Fairley CK. Quadrivalent vaccine-targeted human papillomavirus genotypes in heterosexual men after the Australian female human papillomavirus vaccination programme: a retrospective observational study. Lancet Infect Dis. 2016 Jun 6. pii: S1473-3099(16)30116-5. doi: 10.1016/S1473-3099(16)30116-5. [Epub ahead of print]
See also the Fresh Science story.