Background Australia provided free quadrivalent human papillomavirus vaccines to 12–18-year-old girls and women aged ≤26 years from mid-2007 until the end of 2009. After this time, only girls aged 12–13 years had access to free vaccines.

Methods Before and after the study, of the proportion of new patients attending Melbourne Sexual Health Centre from mid-2004 to mid-2011, diagnosed with genital warts (GW) by risk group.

Results From July 2004 to June 2011, 52 454 new patients were seen at Melbourne Sexual Health Centre and 5021 (9.6%, 95% CI 9.3% to 9.8%) were diagnosed with GW. From July 2004 to June 2007, the proportions with GW either increased or did not change in all groups. Comparing the two 12-month periods of 2007/2008 and 2010/2011, GW declined in women under 21 years from 18.6% to 1.9% and in heterosexual men under 21 years from 22.9% to 2.9%. The ORs per year for diagnosis of GW adjusted for number of sexual partners from July 2007 until June 2011 in women and heterosexual men <21 years were 0.44 (95% CI 0.32 to 0.58) and 0.42 (95% CI 0.31 to 0.60), respectively. There was no significant change in GW in women ≥30 years (OR 0.97, 95% CI 0.84 to 1.12), heterosexual men ≥30 years (OR 0.97, 95% CI 0.89 to 1.06) or in homosexual men (OR 0.95, 95% CI 0.85 to 1.07).

Conclusion The dramatic decline and near disappearance of GW in women and men under 21 years of age, 4 years after commencing this programme, suggest that the basic reproductive rate has fallen below one.