Changes in Childhood Immunization Rates by County Characteristics in Michigan: 2017-2023.

Abstract

To describe changes in Michigan's childhood immunization rates by county sociodemographic characteristics during 2017-2023. We analyzed county-level data from Michigan's immunization registry. For each quarter from quarter 1 2017 through quarter 1 2023, we calculated the mean completion rate of a childhood immunization composite, an adolescent immunization composite, the male human papillomavirus (HPV) vaccination series, and the female HPV vaccination series. We assessed changes in these rates among all Michigan counties and among county subgroups defined by median household income, rurality, and uninsurance rate. During the study period, the mean completion rate of the childhood and adolescent immunization composite declined from 75.7% to 66.8% and from 80.7% to 74.7%, respectively. The mean completion rate of the male and female HPV vaccination series increased from 35.1% to 42.3% and from 43.4% to 45.2%, respectively. These increases were smaller than the increase predicted by prepandemic trends. In counties with lower income and higher uninsurance, declines in the mean completion rate of both composite measures were greater compared with counties with higher income and lower uninsurance, whereas increases in the mean completion rate of the male HPV vaccination series were smaller. Changes according to rurality were inconsistent. Routine childhood and adolescent immunizations are declining in Michigan, and increases in HPV vaccination are slowing, particularly in counties with lower income and higher uninsurance rates. Findings suggest progress toward increasing childhood immunizations is stalling. Targeted efforts to increase immunizations in counties with lower income and higher uninsurance rates may be warranted.