A population-level assessment of factors associated with uptake of adolescent-targeted vaccines in Michigan.

Purpose: Increases in adolescent vaccine coverage are needed. The aim of this study was to identify population-level clinical and demographic factors associated with adolescent vaccination.

Methods: A retrospective analysis of data from the Michigan Care Improvement Registry (MCIR), a statewide immunization registry, was performed for 2006-2010. The sample included 1,252,655 adolescents aged 11-18 years. Vaccine coverage levels were calculated for tetanus-diphtheria-acellular pertussis (Tdap), meningococcal conjugate (MCV4), flu (seasonal influenza), and human papillomavirus, females only (HPV) vaccines. For the subset of adolescents enrolled in Medicaid, claims data were used to obtain information about the type of visits in which vaccines were administered.

Results: As of 2010, statewide coverage levels for Tdap and MCV4 vaccines were 46.0% and 46.5%, respectively whereas only 15% of females had completed the HPV vaccine series. Only one in four female adolescents were up to date for all three of these vaccines. Statewide coverage among adolescents for flu vaccine during the 2009-2010 season was 8%. Age was the most significant predictor of HPV vaccination, whereas health care-associated factors (provider type and childhood immunization history) were the strongest predictors for the other three vaccines. Older adolescents were less likely to have received the flu vaccine but more likely to have receive HPV vaccine doses than younger adolescents. Among Medicaid-enrolled adolescents, most Tdap, MCV, and first-dose HPV vaccines, but only 29% of flu doses, were administered during preventive visits.

Conclusions: Noted variability in adolescent vaccine coverage by age, vaccine type, and health care-associated factors provides a framework for developing future outreach activities to increase adolescent vaccine use.