NEW YORK (Reuters Health) – A school-based, gender-neutral human papillomavirus (HPV) program reduced anal, penile and oral vaccine-targeted genotypes in young men who have sex with men (MSM), researchers say.
“We saw a huge reduction in HPV-related diseases in females in several countries after the implementation of a vaccination program, and therefore we also expected to see some reductions in gay and bisexual men,” Dr. Eric Chow of the Melbourne Sexual Health Centre, Alfred Health in Victoria told Reuters Health by email.
But the magnitude of the reduction was a surprise, he said. “In particular, we saw a 70% reduction in anal HPV genotypes 16, which causes most anal cancers. This suggests that vaccination may lead to a reduction in anal cancer.”
“Furthermore,” he added, “we also saw significant reduction in vaccine-preventable HPV genotypes in the genital site and oral cavity. These findings are very exciting.”
As reported in The Lancet Infectious Diseases, Dr. Chow and colleagues investigated HPV prevalence in young MSM before and after the implementation of a school-based quadrivalent HPV (genotypes 6, 11, 16, and 18) vaccination program for boys in Australia in 2013.
Four hundred MSM ages 16-20 years were recruited from two successive birth cohorts. The first was before implementation of gender-neutral vaccination (HYPER1 study, 2010-12); the second was the post-vaccination cohort (HYPER2 study 2017-18).
Each cohort included 200 individuals, and the median number of lifetime male partners in both was 10.
The prevalence of any anal quadrivalent vaccine-preventable HPV genotype was higher in the pre- (28%) than in the post-vaccination cohort (7%; adjusted prevalence ratio, 0.24); this was driven largely by decreases in HPV6, followed by HPV11, 16, and 18.
Anal HPV16 and 18 prevalences were also significantly reduced in the post-vaccination cohort compared to the pre-vaccination cohort (PR, 0.31).
In addition, the prevalence of any penile quadrivalent vaccine-preventable HPV genotype was higher in the pre-vaccination cohort (12% vs. 6%), driven by decreases in HPV 6 and 11, but not by 16 and 18.
Further, the prevalence of any oral quadrivalent vaccine-preventable HPV genotype was higher in the pre-vaccination cohort (4% vs. 1%).
No cases of oral HPV6 or 11 were detected in HYPER2. Overall, comparing the pre-vaccinated cohort with the 149 confirmed vaccinated men from HYPER2 showed a reduction in any quadrivalent vaccine-preventable HPV genotype for anal (PR, 0.09) and penile (PR,0.18) infection, but not for oral infection (PR, 0.17).
Dr. Marianne van der Sande of University Medical Centre Utrecht, coauthor of a related editorial, commented in an email to Reuters Health. “Available HPV vaccines are highly effective and safe, but it is vaccinations, not vaccines, that safe lives. Vaccines can only be effective if those who need them are vaccinated in time. MSM do not benefit from female-only vaccinations.”
“Vaccination at a young age is key, preferably before age 14, as most people get infected soon after becoming sexually active,” she noted. “The largest HPV burden occurs among populations with poorest access to both vaccinations and healthcare services that can diagnose and treat vaccine-preventable HPV diseases.”
“To enable high, sustained vaccination uptake among young adolescents, their concerns, needs and perceptions should be taken into account,” she added. “This requires context-specific approaches. That may take time and resources, but will be more effective and efficient than non-targeted campaigns with low uptake.”
“Integration of public health basics in primary school curricula can be a strong foundation to clarify the rationale for and uptake of timely vaccination,” she concluded.
The study was funded in part by Merck. Dr. Chow and five coauthors received grant money from the company to conduct the HYPER2 study.
SOURCE: https://bit.ly/2SaTRWT and https://bit.ly/3z1P9eE The Lancet Infectious Diseases, online May 24, 2021.
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