No effect of human papillomavirus vaccination on sexual debut of school children

We aimed to describe sexual behaviour and knowledge about sexually transmitted infections (STI) among Danish adolescents stratified by gender and human papillomavirus (HPV) vaccination status. We conducted a questionnaire study in Viborg Municipality, Denmark. A validated questionnaire was sent to all ninth-grade pupils without prior notice to either teachers or pupils. In 2014, 776 pupils attended the ninth grade, 685 (88%) of whom participated in the study. A total of 376 (55%) reported having received the HPV vaccine. HPV-vaccinated girls (p = 0.03) and boys (p = 0.04) had more knowledge about STI than those who were unvaccinated. A total of 157 (23%) pupils reported having had intercourse, with a mean age at debut of 14.4 (standard deviation ± 1) years and no significant difference by gender or vaccination status. From first to latest intercourse, we found a significant decline in total condom use among all pupils (p < 0.001), with the most significant decline being observed among HPV-vaccinated pupils (p < 0.001), in particular among HPV-vaccinated girls (p < 0.001). In addition, a non-significant increase was observed in the lack of use of contraception (16% versus 27%) from first to latest intercourse, with no difference being observed by gender or vaccination status. Overall, no difference in the proportion of pupils with sexual debut or mean age at sexual debut was observed between HPV-vaccinated and unvaccinated adolescents in Denmark. However, HPV-vaccinated adolescents were more likely to stop using a condom despite their higher STI awareness. Author Anne Hammer received funding from the Danish Cancer Society. not relevant.