Use of human papillomavirus (HPV) vaccine causes dramatic fall in genital warts

An important new study by a team of researchers working in a sexual health clinic in Melbourne, Australia has shown that 4 years after a government funded program of vaccinating girls and women aged 12-18 there was a dramatic decline in new cases of genital warts in heterosexual women and also of men with a new diagnosis of genital warts. Cases of genital warts attending the Melbourne Sexual Health Centre fell from 18.6% of all new diagnosis in women under 21 in 2007-2008  to 1.9% in 2010-2011. Interestingly there was a similar dramatic fall in new cases of genital warts in men under 21 over the same time period from 22.9% to 2.9%. The odds ratio per year for diagnosis of genital warts that was adjusted for number of sexual partners from July 2007 until June 2011 in women <21 years was 0.44 (95% CI 0.32 to 0.58) and in heterosexual men aged <21 was 0.42 (95% CI 0.31 to 0.60)  – a fall of over 55% in both sexes.

There was no drop in the incidence of new genital warts diagnosis in women aged over 30 or in men who have sex with men adding weight to the authors’ conclusions that the fall in new wart cases in younger men and women was a consequence of vaccination. It is argued that a reduction in new infections in young women had resulted in a reduced pool of infection and hence also caused a similar drop in their male sexual partners.

The Australian government was providing the vaccine free to all girls and women aged 12-18 from 2007 until the end of 2009. Since then free vaccine has been only offered girls aged 12-13.  The vaccine used in Australia contains antigens from HPV 6 and 11 which are the commonest HPV genotypes associated with genital warts as well as HPV 16 and 18 associated with cervical cancer.

Unfortunately the quadrivalent vaccine is not the one chosen for use by the Department of Health in the UK. A recent study which we reported earlier showed that the quadrivalent vaccine is more cost effective than the bivalent vaccine currently recommended for use in the UK.

 

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