Examining determinants for reporting suspected adverse events following HPV vaccination in Denmark

HPV vaccination has been offered to 12-year-old girls as part of the Danish Childhood Vaccination Programme since 2009. From 2013, an increasing number of suspected severe adverse events (AE) without a documented causal link to the vaccine was observed, resulting in public concerns about vaccine safety and a decline in uptake. This study aimed at describing the group of females reporting AE and comparing them to vaccinated peers not reporting AE. A questionnaire focusing on demographics, lifestyle, and health-related issues was distributed to 251 female cases who had reported severe AE and 1,003 female controls randomly selected from the population-based Danish Vaccination Registry. All had been HPV-vaccinated. There were no significant differences on measures of self-reported psychiatric or somatic conditions before vaccination. More cases reported being physically very active prior to first HPV vaccination (OR 4.2) whereas fewer cases than controls sometimes (OR 0.31) or often/always (OR 0.36) felt sad. This is unexpected because two recent Danish registry-based case-control studies concluded that females reporting severe AE were more likely to consult a psychologist/psychiatrist and to have pre-existing psychiatric conditions before first HPV vaccination. One of these studies also showed that cases had increased health-care seeking regarding a number of somatic conditions prior to first vaccination. Our study adds value when seeking to understand the lifeworld of the affected females and their interpretations of their everyday lives pre- and post-HPV vaccination.