HPV Vaccine Shows Sustained Real-World Impact in Denmark

A cohort study in Denmark has confirmed that national human papillomavirus (HPV) vaccination campaigns have significantly reduced infections with the cancer-linked HPV types 16 and 18 among vaccinated women. The findings, published in Eurosurveillance, offer real-world data that support long-term protection through vaccination and suggest a level of population immunity.

HPV types 16 and 18 nearly eliminated in vaccinated groups

In Denmark, girls have been eligible for free HPV vaccination since 2008. The study examined data from more than 17,000 women aged 22 to 30 years participating in cervical screening between 2017 and 2024. These participants had been vaccinated during adolescence with either the quadrivalent vaccine covering types 6, 11, 16 and 18, or the nonavalent vaccine, which was introduced in 2017.

Researchers analysed cervical samples to assess the presence, persistence and incidence of high-risk HPV. Among vaccinated women, the prevalence of HPV types 16 and 18 dropped below 1% by 2021, compared to pre-vaccination levels of 15% to 17%. By contrast, in unvaccinated women, HPV16/18 remained at a 5% prevalence, suggesting indirect protection through population immunity.

High-risk types not covered by vaccine remain prevalent

While vaccine-targeted HPV types showed substantial declines, other high-risk HPV types not included in the vaccines were still frequently detected. These types accounted for roughly one third of HPV-positive cases and were identified in both vaccinated and unvaccinated women. The study also found a higher incidence of these non-vaccine HPV types in vaccinated participants.

This persistence suggests that while the vaccine provides strong protection against covered strains, it does not eliminate the risk of HPV-related disease entirely. Continued cervical screening remains important, particularly until individuals vaccinated with the nonavalent vaccine reach the screening age.

Implications for screening strategies

The authors propose that screening protocols could be revised for cohorts vaccinated with broader-protection vaccines. However, the ongoing presence of non-vaccine high-risk HPV types in both groups indicates that reducing screening intensity should be considered cautiously and tailored to vaccine type and coverage.

Reference: Nonboe MH, Napolitano GM, Schroll JP, et al. Human papillomavirus prevalence in first, second and third cervical cell samples from women HPV-vaccinated as girls, Denmark, 2017 to 2024: data from the Trial23 cohort study. Eurosurveillance. doi: 10.2807/1560-7917.ES.2025.30.27.2400820

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