SS 12-07LOW PREVALENCE OF GENITAL HUMAN PAPILLOMAVIRUS AMONG YOUNG HETEROSEXUAL MALES IN AUSTRALIA: EVIDENCE FOR THE IMPACT OF HERD PROTECTION FROM THE FEMALE VACCINATION PROGRAM

02. Epidemiology and natural history
D.A. Machalek 1, E.P. Chow 2, S.M. Garland 1, R. Wigan 3, A.M. Cornall 1, C.K. Fairley 2, J.M. Kaldor 4, J.S. Hocking 5, M.Y. Chen 2, S.N. Tabrizi 1.
1Department of Microbiology and Infectious Diseases, The Royal Women’s Hospital and Murdoch Childrens Research Institute, Melbourne, Victoria (Australia), 2Melbourne Sexual Health Centre, Alfred Health and Central Clinical School, Faculty of Medicine, Nursing and Health Sciences, Monash University, Melbourne, Victoria (Australia), 3Melbourne Sexual Health Centre, Melbourne, Victoria (Australia), 4The Kirby Institute for infection and immunity in society, University of New South Wales, Sydney (Australia), 5Melbourne School of Population and Global Health, University of Melbourne, Melbourne, Victoria (Australia)

Background / Objectives

Vaccination of adolescent females with the quadrivalent human papillomavirus (qHPV; HPV 6/11/16/18) vaccine commenced in Australia in 2007. Subsequently, a decrease in the prevalence of qHPV genotypes has been observed in, both vaccinated and unvaccinated women aged <25 years. In 2013, the program was expanded to include adolescent males. We evaluated genital HPV prevalence in sexually active 16–35 year old unvaccinated heterosexual males.


Methods

In 2014/15, a total of 596 heterosexual males aged 16–35 years were recruited for HPV testing from sexual health clinics and other community based settings across Australia. Participants provided a self-collected penile swab and completed a questionnaire. Genotyping of HPV was performed using Roche Linear Array. Adjusted prevalence ratios (aPRs) were estimated using binomial log linear regression, for qHPV and HR-HPV excluding HPV16/18, comparing unvaccinated men aged <25 to those ≥25 years. PRs were adjusted for source of recruitment, smoking status, age at first sex, and number of female partners in the previous 12 months. Vaccination status was confirmed against the National HPV Vaccination Program Register (NHVPR).


Results

NHVPR and HPV data were available for 477 (80%) participants (median age 23; IQR 20-27). Most (n=465, 97%) had not received the HPV vaccine. Of these, 72% were recruited from sexual health clinics, 29% were current smokers, 44% were ≤16 years of age at first sex, and 70% reported ≥2 female sexual partners in the previous 12 months. Prevalence of qHPV types was significantly lower in men aged <25 years compared with men aged ≥25 years: 3.4% [95% CI: 1.6­–6.2%] vs 14.6% [95% CI: 9.7–20.8%] respectively (p<0.001); aPR 0.28 [95% CI: 0.13–0.58%; p=0.001]. Prevalence of other HR-HPV types excluding 16/18 did not change with increasing age and was 17.4% [95% CI: 13.0–22.4%] among men aged <25 years, and 17.0% [95% CI: 12.0–23.1%] among those ≥25 years [p=0.925]; aPR 1.06, [95% CI: 0.70–1.60; p=0.777]). Men in the younger age group were significantly less likely to report current genital warts (7.1% [95% CI: 4.3–11.0%] versus 14.7% [95% CI: 9.6–21.3%] among those <25 and ≥25 years, respectively [p=0.013]; aPR 0.18, [95% CI: 0.06–0.53; p=0.002]).


Conclusion

In a cohort of highly sexually active unvaccinated heterosexual males we observed a significantly lower prevalence of qHPV types, but not other HR-HPV types, in males aged <25 years. Our results suggest that males may benefit almost to the same extent as females from a female-only vaccination program under high vaccine coverage (~70%), due to herd protection.


References