A quadrivalent HPV vaccination program for females dramatically reduced the prevalence of virus among unvaccinated young men, according to researchers from Australia. The data indicated male patients may benefit as much as female patients from a female-only, high-coverage vaccination program, they wrote.
“Surveillance data from several countries have provided growing evidence for the population-level benefits of HPV vaccination in young women, both direct, and through herd protection of those who remain unvaccinated,” Dorothy A. Machalek, BSc, MPH, of the department of microbiology and infectious diseases at The Royal Women’s Hospital, Melbourne, and colleagues wrote. “To further investigate the evidence for male herd protection through the female vaccination program, we estimated the age-specific prevalence of penile HPV genotypes among 16- to 35-year-old unvaccinated heterosexual males recruited through a network of clinic and community based settings across Australia.”
The researchers studied 511 male patients recruited from two national HPV studies — the National HPV Monitoring Program (IMPACT) and the Impact of HPV Vaccination Research Study (IMPRESS) — between January 2014 and May 2016. Machalek and colleagues analyzed HPV prevalence by reviewing self-collected penile swabs and questionnaires on risk and demographic factors.
Men aged 25 years or younger had a significantly lower HPV prevalence than those older than 25 years, the researchers reported (3.1% [95% CI, 1.5-5.7] vs. 13.7% [95% CI, 8.9-20.1]). Younger males had a 78% lower prevalence of HPV genotypes 6, 11, 16 and 18 compared with those aged older than 25 years. However, Machalek and colleagues reported high-risk genotypes other than 16 and 18 were similar in both age groups (16.8% [95% CI, 12.6-21.9] in men aged 25 years and under vs. 17.9% [95% CI, 12.4-25] in men aged older than 25 years).
The researchers attributed the difference in prevalence to herd protection from vaccination in females because of the similarity of infection rates for HPV genotypes not targeted by the vaccine.
“Cost effectiveness studies have been conducted to help inform whether any further health benefits from the addition of male HPV vaccination would be obtained. However, these have been based on mathematical modelling without actual male prevalence data such as those presented in this study,” Machalek and colleagues wrote. “With the introduction of male vaccination in Australia, ongoing surveillance of HPV prevalence with linkage to the national vaccine register will allow monitoring of the impact of HPV vaccination over time and will inform whether routine vaccination of boys will result in any benefits over and above that which have already been achieved through the existing female vaccination program.” – by Andy Polhamus
Disclosure: Machalek reports receiving educational grants from Seqirus for work related to HPV. Please see the full study for a complete list of all other researchers’ relevant financial disclosures.