Observational studyPloS one2019
An observational study comparing HPV prevalence and type distribution between HPV-vaccinated and -unvaccinated girls after introduction of school-based HPV vaccination in Norway.
Observational study in PloS one, 2019. The graph could read no effect estimate from its abstract, so it casts no vote on the map. An erratum has been issued. It is linked to trial NCT02934724 (Impact of HPV Vaccine On The Prevalence Of Human Papillomavirus In Mouth And Vagina In Norway), which is not on this map. Cited by 15 papers, 4 of them syntheses that pooled it.
What it found
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The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Impact of HPV Vaccine On The Prevalence Of Human Papillomavirus In Mouth And Vagina In Norway
Who cites it
15 citing papers in PubMed, 4 syntheses or guidelines pooled it, 25 citations in OpenAlex.
- Effects of human papillomavirus (HPV) vaccination programmes on community rates of HPV-related disease and harms from vaccination.The Cochrane database of systematic reviews · 2025Pooled it
- Prevalence of non-vaccine high-risk HPV cervical infections in vaccinated women: a systematic review and meta-analysis.BMC infectious diseases · 2025Pooled it
- Low Rates of Dual-Site and Concordant Oral-Cervical Human Papillomavirus Infections and Cancers: A Systematic Review.Frontiers in oncology · 2022Pooled it
- The Effect of Prophylactic HPV Vaccines on Oral and Oropharyngeal HPV Infection-A Systematic Review.Viruses · 2021Pooled it
- Protection Against Persistent HPV-16/18 Infection After Different Number of Doses of Quadrivalent Vaccine in Girls and Young Women: A Randomized Clinical Trial.JAMA network open · 2025Trial
- HPV Type Replacement After HPV Vaccination.Current topics in microbiology and immunology · 2026Review
- Prevalence and genotype distribution of HPV infection among women in 2021-2023 in southern Iran: The rising trend of HPV infection among women.BMC women's health · 2025Article
- Prevalence of human papillomavirus (HPV) genotypes in patients with clinical symptoms in Kermanshah, western Iran: a cross-sectional study.BMC infectious diseases · 2025Article
- Human Papillomaviruses Genotype Distribution and Replacement by Year from 2014 to 2020 in Beijing, China.Women's health reports (New Rochelle, N.Y.) · 2024Article
- Human papillomavirus infection and seroprevalence among female university students in Mexico.Human vaccines & immunotherapeutics · 2022Article
- Acceptability of HPV Vaccination in Young Students by Exploring Health Belief Model and Health Literacy.Vaccines · 2022Article
- Article
- The Prevalence of High- and Low-Risk Types of HPV in Patients with Squamous Cell Carcinoma of the Head and Neck, Patients with Chronic Tonsillitis, and Healthy Individuals Living in Poland.Diagnostics (Basel, Switzerland) · 2021Article
- Strong reduction in prevalence of HPV16/18 and closely related HPV types in sexually active adolescent women following the introduction of HPV vaccination in Argentina.Papillomavirus research (Amsterdam, Netherlands) · 2020Article
- Article
Corrections and comments
- Erratum issued
Authors and funding
8 authors at 4 institutions in 2 countries.
Funding
Abstract
backgroundMany countries have initiated school-based human papillomavirus (HPV) vaccination programs. The real-life effectiveness of HPV vaccines has become increasingly evident, especially among girls vaccinated before HPV exposure in countries with high vaccine uptake. In 2009, Norway initiated a school-based HPV vaccination program for 12-year-old girls using the quadrivalent HPV vaccine (Gardasil®), which targets HPV6, 11, 16, and 18. Here, we aim to assess type-specific vaginal and oral HPV prevalence in vaccinated compared with unvaccinated girls in the first birth cohort eligible for school-based vaccination (born in 1997).
methodsThis observational, cross-sectional study measured the HPV prevalence ratio (PR) between vaccinated and unvaccinated girls in Norway. Facebook advertisement was used to recruit participants and disseminate information about the study. Participants self-sampled vaginal and oral specimens using an Evalyn® Brush and a FLOQSwab™, respectively. Sexual behavior was ascertained through a short questionnaire.
resultsAmong the 312 participants, 239 (76.6%) had received at least one dose of HPV vaccine prior to sexual debut. 39.1% of vaginal samples were positive for any HPV type, with similar prevalence among vaccinated and unvaccinated girls (38.5% vs 41.1%, PR: 0.93, 95% confidence interval [CI]: 0.62-1.41). For vaccine-targeted types there was some evidence of lower prevalence in the vaccinated (0.4%) compared to the unvaccinated (6.8%) group (PR: 0.06, 95%CI: 0.01-0.52). This difference remained after adjusting for sexual behavior (PR: 0.04, 95%CI: 0.00-0.42). Only four oral samples were positive for any HPV type, and all of these participants had received at least one dose of HPV vaccine at least 1 year before oral sexual debut.
conclusionThere is evidence of a lower prevalence of vaccine-targeted HPV types in the vagina of vaccinated girls from the first birth cohort eligible for school-based HPV vaccination in Norway; this was not the case when considering all HPV types or types not included in the quadrivalent HPV vaccine.
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