Adolescence, sexually transmitted infections and human papillomavirus vaccination.

INTRODUCTION: Human papillomavirus (HPV) is the most common sexually transmitted infection, with an 80% lifetime risk of infection. This study investigated adolescents' knowledge of sexually transmitted infections and examined whether this knowledge was associated with HPV vaccination status or influenced decisions regarding condom use. METHODS: This study has a cross-sectional design and was based on data from an annual questionnaire distributed to all ninth-graders in Tønder, Denmark, between 2020 and 2024. RESULTS: Among 1,254 pupils in ninth grade, 866 (69%) answered the questionnaire. 20% had their sexual debut at a median age of 14 years, and most within the year leading up to the questionnaire. Within the overall group, knowledge of three or more STIs was associated with HPV vaccination (p = 0.001). At their most recent sexual activity, 62% used condoms and/or oral contraceptives. The girls reported greater reliance on contraceptives than boys across different circumstances, with rates of 70-80%compared with 50-55%, respectively. The HPV vaccination was associated with an increased use of condoms. CONCLUSIONS: HPV-vaccinated adolescents knew more about sexually transmitted diseases and more often used condoms. FUNDING: None. TRIAL REGISTRATION: Not relevant.