Surveillance across 10 specialist sexual health services in England detected a measurable fall in vaccine-type anal HPV. The study team analysed 5,787 rectal swabs from gay, bisexual and other men who have sex with men (GBMSM) collected in two phases: 3,291 specimens in Phase 1 (2017–19) and 2,496 in Phase 2 (2021–24). Data indicated a 36% decline in anal HPV16/18 prevalence between the two phases. This decline occurred in the context of a national programme that began in 2016 offering targeted HPV vaccination to GBMSM.
Short and direct: vaccine-type prevalence fell. Yet the pattern in subgroup comparisons was not straightforward, and the authors presented multiple explanatory possibilities based on available surveillance data.
The investigators used residual rectal swabs taken for chlamydia and/or gonorrhoea screening in sexual health clinics. Specimens were anonymised and linked to surveillance records containing sociodemographic variables, prior STI diagnoses, and reported HPV vaccination recorded in the UK Health Security Agency's national STI surveillance system. An in-house multiplex PCR with Luminex-based genotyping was used to detect type-specific HPV DNA in the samples. The source did not report additional laboratory validation parameters or assay sensitivity and specificity in the abstract.
Patients were aged ≤45 years, but the abstract did not provide further age distribution or behavioural risk details in the text provided here. The sample frame was clinic attendees undergoing STI screening, which the authors acknowledged as a sentinel population for monitoring HPV trends in GBMSM.
Investigators compared vaccine-type prevalence across phases and between individuals with and without any reported HPV vaccination. Overall prevalence of HPV16/18 was reported as 16.6% (95% CI 15.2–18.1) among those with recorded vaccination and 15.8% (95% CI 14.5–17.1) among those without recorded vaccination. Those point estimates were similar, despite the population-level decline between phases. The authors did not present vaccine dose schedules, timing of vaccination relative to specimen collection, or completeness of individual immunisation records in the abstract.
These comparable prevalences by recorded vaccination status contrast with the phase-to-phase decline and prompted the study team to caution against simple vaccine effectiveness calculations from these surveillance data.
The study team reported that available data did not permit accurate estimation of vaccine effectiveness. They attributed this limitation to several factors: underreporting of vaccinations in the surveillance dataset, the presence of herd protection effects that would lower prevalence even among unvaccinated or unrecorded individuals, and bias in who received vaccination. The abstract explicitly lists these three influences as likely to have confounded direct vaccine-effectiveness estimates.
The investigators therefore treated their analysis as ecological. They compared population-level prevalence changes over time rather than calculating individual-level effectiveness measures, because the surveillance linkage and reporting completeness were insufficient for robust causal inference at the person level.
Data indicated reduced circulation of vaccine-type HPV eight years after the targeted programme began. The authors noted that the decline in HPV16/18 prevalence is consistent with impact from the vaccination programme. They also emphasised that the evidence is ecological; direct attribution to vaccination at the individual level could not be confirmed with the available surveillance records.
This surveillance signal is clinically relevant for sexual health services that care for GBMSM. Falling vaccine-type prevalence may translate into fewer HPV-related lesions over time, but the abstract did not provide clinical outcome data such as anal intraepithelial neoplasia or cancer endpoints. The source did not report on subgroup effects by age at vaccination, HIV status, or number of vaccine doses in the abstract.
Limitations reported by the authors included underreporting of vaccinations to the national STI surveillance system, potential herd protection effects confounding comparisons between vaccinated and unvaccinated individuals, and biased vaccine uptake among clinic attendees. The study ended on these concrete uncertainties: available surveillance data could not produce an accurate vaccine effectiveness estimate, and the analysis remained ecological. Further work was implied—better linkage of vaccination records, assessment of clinical outcomes, and strategies to address underreporting—but the abstract did not specify next regulatory milestones or named future studies.