An observational study comparing HPV prevalence and type distribution between HPV-vaccinated and -unvaccinated girls after introduction of school-based HPV vaccination in Norway

Autoři: Espen Enerly aff001;  Ragnhild Flingtorp aff001;  Irene Kraus Christiansen aff002;  Suzanne Campbell aff001;  Mona Hansen aff002;  Tor Åge Myklebust aff003;  Elisabete Weiderpass aff005;  Mari Nygård aff001
Působiště autorů: Department of Research, Cancer Registry of Norway, Oslo, Norway aff001;  Department of Microbiology and Infection Control, National HPV Reference Laboratory, Akershus University Hospital, Lørenskog, Norway aff002;  Department of Registration, Cancer Registry of Norway, Oslo, Norway aff003;  Department of Research and Innovation, Møre and Romsdal Hospital Trust, Ålesund, Norway aff004;  International Agency for Research on Cancer (IARC), World Health Organization, Lyon, France aff005
Vyšlo v časopise: PLoS ONE 14(10)
Kategorie: Research Article



Many 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).


This 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.


Among 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.


There 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.

Klíčová slova:

Cohort studies – Human papillomavirus – Human papillomavirus infection – Human sexual behavior – Vaccination and immunization – Vaccines – Norway – Facebook


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