Do parental education and income matter? A nationwide register-based study on HPV vaccine uptake in the school-based immunisation programme in Norway

OBJECTIVE Vaccine against human papillomavirus (HPV) has been offered free of charge to all 12-year-old girls in Norway since 2009. Nevertheless, the uptake of HPV vaccine is lower than for other childhood vaccines. The aim of this study was to examine whether parental education and income are associated with initiation and completion of HPV vaccination. DESIGN Nationwide register-based study. SETTING Publicly funded childhood immunisation programme in Norway. PARTICIPANTS 91,405 girls born between 1997 and 1999 and registered in the Norwegian Central Population Registry were offered HPV vaccine during the first 3 programme years. Of these, 84,139 had complete information on all variables and were included in the study. MEASUREMENTS Information on HPV-vaccination status was obtained from the Norwegian Immunisation Registry. Data on socioeconomic factors were extracted from Statistics Norway. Risk differences (RDs) and CIs were estimated with Poisson regression. RESULTS In the study sample, 78.3% received at least one dose of HPV vaccine and 73.6% received all three doses. High maternal education was significantly associated with lower probability of initiating HPV vaccination (multivariable RD=-5.5% (95% CI -7.0% to -4.0%) for highest compared with lowest education level). In contrast, high maternal income was significantly associated with higher probability of initiating vaccination (multivariable RD=10.1% (95% CI 9.0% to 11.3%) for highest compared with lowest quintile). Paternal education and income showed similar, but weaker, associations. The negative association between education and initiation was only seen for incomes below the median value. CONCLUSIONS In spite of the presumably equal access to HPV vaccine in Norway, we found socioeconomic disparities in vaccine uptake. More studies are needed to explain the underlying factors responsible for the observed socioeconomic differences. Insight into these factors is necessary to target information and increase vaccination coverage to ultimately reduce HPV-related disease across socioeconomic barriers.