Time and geographic variations in human papillomavirus vaccine uptake in Washington state.

This study examines geographic variations of human papillomavirus (HPV) vaccine uptake, the most significant disparity in HPV vaccination, in Washington State. We evaluated Washington State Immunization Information System (WA-IIS) data on target age (11-12 year old adolescents) between 2008 and 2018. A Bayesian spatio-temporal analysis was conducted to examine uptake at the census tract level. Urban-rural disparities in vaccine rates were assessed using t-tests. Persistently high and low vaccine areas and their contributing sociodemographic factors were then identified using a multinomial logistic regression. HPV vaccine uptake gradually increased after 2010, but remained persistently low. Average vaccine uptake rates from 2010 through 2018 in urban areas were 11%-34% for initiation and 4-19% for completion. These rates were 9-22% initiation and 3-11% completion in rural areas. We observed statistically significant (p < 0.05) differences between the estimated vaccine rates for urban and rural census tracts. Race/ethnicity and socioeconomic status were associated with this urban-rural disparity. The odds of being in low vaccine rural areas increased with increase in Area Deprivation Index (ADI) (OR = 1.14, CI = (1.10, 1.19)), and decreased with percentage increase in Black (OR = 0.43, CI = (0.02, 0.85)) and Hispanic (OR = 0.97, CI = (0.94, 1.00)) population. Bayesian spatial analysis was effective in capturing spatio-temporal patterns in HPV vaccine rates and identifying areas with persistently low vaccination over time. This analytic approach can be used to guide public health policies and geographically target interventions to reduce HPV vaccine disparities and to prevent future HPV-related cancers.