A large study from Australia has demonstrated a significant reduction in genital warts following introduction of the quadrivalent HPV vaccination programme in mid-2007.

Eight sexual health services provided retrospective data from 2004 to 2011. Data were collected on demographics, sexual behaviour and diagnosis of genital warts; two large clinics also collected self-reported HPV vaccination status of new patients from 2009. The number of patients diagnosed with new genital warts was presented as a proportion of new patients seen. The proportion of Australian born patients who tested positive for chlamydia was used as a comparison.

The proportion of women diagnosed with warts during the pre-vaccination period rose from 8.9% in 2004 to 9.6% in 2007; this fell to 2.7% in 2011 during the vaccination period.

For women under 21 the proportion diagnosed with genital warts dropped from 11.5% in 2007 to 0.85% in 2011 (P < 0.001). None of those who reported having had HPV vaccination were noted to have genital warts, compared with 10.5% in this age group in 2006 when all women were unvaccinated. For heterosexual men under 21, there was a dramatic decline in the proportion diagnosed with warts from 12.1% in 2007 to 2.2% in 2011 (P < 0.001).

There was no significant decline in the proportion of women aged 21-30 diagnosed with genital warts in the pre-vaccination period. However, this proportion declined from 11.3% in 2007 to 3.1% in 2011, a decrease of 72.6% (P < 0.001). Likewise, the proportion of heterosexual men with warts in this age group decreased from 18.2% to 8.9% (P < 0.001).

There was no significant trend in the proportion of women or heterosexual men aged over 30 diagnosed with genital warts before or during the vaccination period. The trend in proportion of men who have sex with men (MSM) diagnosed with warts appeared to have declined in the vaccination period by 24.7%, from 8.5% to 6.4%.

There was a significant increase in the proportion that tested positive for chlamydia in MSM, and women and heterosexual men under 21 in the vaccination period.

The authors concluded that the greatest decline in genital warts was seen in the group eligible for free quadrivalent HPV vaccine (women under 21 years); many of whom would have been vaccinated at school before becoming sexually active.

The more modest reduction in women aged 21-30 may be explained by lower vaccination coverage. The fall in genital warts seen in two younger age groups of heterosexual men was likely to be due to herd immunity.

The small decline in genital warts in MSM might be explained by the increase in the number attending sexual health screening rather than protection conferred from herd immunity from young women (in the case of bisexual men or homosexual men who had ever had female partners).

In an accompanying editorial,¹ two UK consultants in sexual health gave the study findings a warm welcome. They state that the switch from bivalent to quadrivalent vaccine for the UK national programme in September 2012 should result in a substantial drop in workload for many sexual health clinics attributable to a fall in the incidence of genital warts in five to nine years’ time. Also, the proven efficacy of quadrivalent vaccines against oncogenic HPV may result in reduction in HPV-16 and HPV-18 associated cancers such as cervical, oropharyngeal and other head and neck cancers.

The Australian government has started a publicly funded HPV programme in 2013 for 12 to 13-year-old boys with a catch up for 14 to 15-year-old boys. This decision was based on the increasing incidence of HPV-related oropharyngeal cancers in men and also the fact that young MSM would not benefit from heterosexual herd immunity.

Time will tell if the UK government will follow suit but it might not be long before those of us in primary care see the reduction in impact due to other HPV-related conditions such as cervical smear abnormalities and certain cancers.

Dr Richard Ma