205 - Census Tract-Level Nirsevimab Immunization Rates among Infants in a Southwest Ohio Medicaid Accountable Care Organization

Publication Number: 2197.205

Anne K. Jackson, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States; Carson Hartlage, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States; Cole Brokamp, University of Cincinnati College of Medicine, Cincinnati, OH, United States; Andrew F. Beck, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States

Background: In 2023, a long-acting monoclonal antibody (nirsevimab), effective at preventing Respiratory Syncytial Virus (RSV) bronchiolitis, was recommended for infants < 8 months in their first RSV season. Multisite data from 2023-2024, and local data from 2024-2025, demonstrate disparities in nirsevimab uptake, with lower uptake among Black infants, publicly-insured infants, and those from lower opportunity areas. Disparities in uptake could worsen existing disparities in bronchiolitis morbidity.

Objective: To identify and characterize area-level clusters of low and high nirsevimab immunization uptake among eligible infants in a Medicaid Accountable Care Organization (ACO).

Design/Methods: We used data from an ACO covering ~50% of all Medicaid-insured infants in 8 Ohio counties to identify nirsevimab-eligible infants (aged < 8 months during 10/1/2024-3/31/2025) and nirsevimab receipt. We geocoded infants' addresses, identifying corresponding census tracts. We excluded tracts with < 5 eligible infants. We calculated nirsevimab uptake by dividing those immunized by those eligible within each tract. We used Moran's I testing to assess geospatial clustering within this population of Medicaid-insured infants. We then used the local Getis-Ord Gi* test to identify tracts with low uptake rates surrounded by other tracts with low rates (low), and tracts with high uptake rates surrounded by other tracts with high rates (high). We compared census tract-level deprivation index scores in low and high uptake clusters using ANOVA.

Results: Of 4573 eligible infants, 1023 (22.4%) received nirsevimab during the study period. Eligible infants were 49% female, 32% Black, and 7% Hispanic. Nearly 95% of addresses were geocoded, and 3941 infants in 304 tracts were included in geospatial analyses. Tracts had a range of 5-118 eligible infants; immunization uptake ranged from 0%-80%. We found significant geospatial clustering in immunization uptake (Moran's I p< 0.0001). We identified 44 statistical "low" immunization clusters and 28 "high" clusters (Getis-Ord GI* threshold p< 0.05; Figure 1). Low uptake clusters were more commonly identified in rural areas while high uptake clusters were more commonly identified in urban areas. There was no difference in deprivation between low and high uptake clusters (p=0.84), potentially because this analysis was conducted entirely with Medicaid recipients.

Conclusion(s): We identified geospatial clusters of low and high nirsevimab uptake among eligible infants in a Medicaid ACO. Such findings may be used to help guide population health strategies focused on equitable immunization access and uptake.

Figure 1. Map of census tract-level immunization rates with clusters of low and high nirsevimab immunization uptake
Legend: Census tracts that were excluded due to having <5 eligible infants are gray. Census tracts identified by the Getis-Ord Gi* test as low and high uptake clusters are designated with red and blue borders, respectively.