Impact of the human papillomavirus (HPV) vaccine on genital wart diagnoses at Auckland Sexual Health Services.

AIM: To review cases of genital warts diagnosed at Auckland Sexual Health Service (ASHS) and to document any change following the introduction of the human papillomavirus (HPV) vaccination. The national HPV immunisation programme, using the quadrivalent vaccine Gardasil, commenced on 1 September 2008. The publically funded programme provides for the ongoing vaccination of girls in year 8 with an initial catch-up programme for young women born after 1 January 1990 until the end of 2010. Monitoring rates of diagnosis of genital warts should provide the earliest clinical indicator of a population response to the vaccine.
METHOD: The proportion of new clients attending ASHS who were diagnosed with genital warts from 1 January 2007 to 31 December 2008 was compared to the proportion diagnosed from 1 January 2009 to 30 June 2010.
RESULTS: 40,793 new clients attended the ASHS between 2007 and June 2010 and genital warts were diagnosed in 3125 (7.7%). Genital warts were diagnosed in 9.2% of new clients in 2007 decreasing to 6.6% for the first 6 months of 2010. Analysis of the subgroup of clients under the age of 20 years, found genital warts in males decreased from 11.5% in 2007 to 6.9% in 2010 while in females the rates decreased from 13.7% to 5.1% over the same time period. In comparison, the rates decreased from 7.5% in 2007 to 5.9% in 2010 for females aged 20 years and over. Thus there was evidence of a significant difference, in the pre to post vaccination era, in the proportion of female clinic visits for genital warts in those aged less than 20 years and those aged 21 years or older (p=0.02) and further a borderline significant difference for males aged less than 20 years (p=0.05).
CONCLUSION: A significant decline in the incidence of genital warts in the target population suggests an early response to the HPV vaccination programme with some evidence of an effect for males aged less than 20 years.