Associations of adverse childhood experiences, sexual identity and sexual risk indicators with HPV vaccination uptake in Denmark – A nationwide epidemiological study

This dual-purpose study assessed whether adverse childhood experiences (ACEs) influence human papillomavirus (HPV) vaccination uptake among girls, young women and boys in Denmark and explored possible differences between HPV-vaccinated and HPV-unvaccinated young women with respect to sexual identity and sexual risk indicators. First, using nationwide register data for 673,609 girls and women born 1985-2009 and 77,667 boys born 2007-2009, Cox proportional hazards regression analyses estimated the influence of ACEs on HPV vaccination uptake through 2021. Secondly, among 9712 young women who participated in the nationally representative Project SEXUS study in 2017-2018, associations of HPV vaccination status with sexual identity and sexual risk indicators were studied in logistic regression analyses. During 1.09 million person-years of follow-up, ACEs were associated with reduced HPV vaccination uptake, with statistically significant confounder-adjusted hazard ratios (aHRs) for Household challenges (girls: aHR = 0.88; 95% confidence interval 0.88-0.89, boys: aHR = 0.88; 0.87-0.90), Material deprivation (girls: aHR = 0.88; 0.87-0.89, boys: aHR = 0.85; 0.82-0.88), and the cumulative number of ACEs (girls: aHR = 0.84; 0.83-0.84, boys: aHR = 0.81; 0.79-0.84, for 3+ vs. 0 ACEs). Significantly fewer non-heterosexual than heterosexual women were HPV-vaccinated (adjusted odds ratio = 0.64; 0.52-0.78), while none of the examined sexual risk indicators differed significantly between HPV-vaccinated and HPV-unvaccinated women. In sum, our study showed that Danish children and young women with one or more ACEs are less likely to become HPV-vaccinated than individuals without ACEs. Also, while non-heterosexual women appear to be undervaccinated against HPV, sexual risk indicators seem not to be associated with HPV vaccination status.