Quadrivalent HPV vaccine was included in the Norwegian childhood immunisation programme in September 2009 to girls in 7th grade. At present, 88% of all eligible girls have received at least one dose, and 86% all three vaccine doses. Since November 2016, catch up vaccination for girls up to 26 years is currently offered in a 2-year programme. In the national HPV-surveillance programme, HPV-testing in urine is used to monitor the impact of HPV vaccination on HPV prevalence and type distribution in pre-screening age. Two HPV prevalence base-line studies have previously been performed in non-vaccinated cohorts at age 17. The HPV-prevalence was 19.9% (girls born 1994) and 15.5% (girls born 1996), respectively.1 In this study, we include also the first vaccinated cohort (born 1997). We present preliminary results of the impact of HPV-vaccination on HPV-prevalence and genotype distribution in 17-year old girls. The study was conducted prior to the start of the catch-up programme.
Two birth cohorts of unvaccinated 17 year old girls (n=~56.000) and one birth cohort of vaccinated 17 year old girls (n=~30.000) were invited by mail to participate in the study. Sampling materials were sent to all girls who signed the informed consent form. The presence of HPV was investigated by using a modified GP5+/6+ PCR protocol 2, followed by hybridization of type-specific oligonucleotide probes coupled to fluorescence labeled polystyrene beads (Luminex suspension array technology)3, detecting and genotyping 37 HPV types (WHO validated protocol). Sample adequacy was evaluated through a beta-globin PCR. Individual vaccination records were retrieved from the Norwegian immunisation register, and HPV-prevalence in vaccinated and unvaccinated girls were compared.
Preliminary results show a significant reduction in overall HPV prevalence in vaccinated as compared to unvaccinated 17-year old girls. The prevalence of high-risk vaccine types 16 and 18 were dramatically reduced, and also for non-vaccine types a reduced prevalence was observed. Analyses are ongoing and detailed results will be presented in the poster.
In this large, population based study, a high effectiveness of the HPV-vaccination progamme for 12 year old girls was demonstrated, and HPV- testing in urine samples was found to be easy and highly feasible for vaccine surveillance in adolescent girls. Except from HPV type 11, quadrivalent vaccine targeted HPV types (HPV 6, 11, 16 and 18) were among the most prevalent types in the unvaccinated cohorts. The prevalence of vaccine types was greatly reduced in vaccinated girls at age 17, and clear evidence of cross-protection of non-vaccine types was observed.
1. Molden T, Feiring B, Ambur OH, Christiansen IK, Hansen M, Laake I, Meisal R, Myrvang E, Jonassen CM, Trogstad L. Human papillomavirus prevalence and type distribution in urine samples from Norwegian women aged 17 and 21 years: A nationwide cross-sectional study of three non-vaccinated birth cohorts. Papillomavirus Research, May (2016).
2. Söderlund-Strand et al. 2009. Modified general primer PCR system for sensitive detection of multiple types of oncogenic human papillomavirus. J. Clin. Microbiol. 47, 541-546.
3. Schmitt et al., 2006. Bead-based multiplex genotyping of human papillomaviruses. J. Clin. Microbiol. 44, 504-512.