D22-14 Evaluation of Potential Disparities in Accessibility and Effectiveness of Nirsevimab in Newborns

Rationale Nirsevimab, a monoclonal antibody, protects infants from Respiratory Syncytial Virus (RSV) through their first winter season and was introduced in Fall 2023. This antibody offers an unprecedented opportunity to reduce serious RSV infection, a leading cause of hospitalization in infants. Intermountain Health (IH) is ensuring that the parents of all newborns born October-March in their hospitals are offered nirsevimab. The goal of this study is to identify any geographic, demographic, or economic disparities in nirsevimab receipt. Methods A limited dataset was sourced from IH hospitals for two RSV seasons: October-March 2023-2024 and 2024-2025. We used descriptive analytics to stratify groups and adjusted for year of receipt, as nirsevimab was more widely available in 2024-2025 than in 2023-2024. Demographics of interest included language spoken, race, ethnicity, birth weight, gestational age, rurality, and delivery hospital. Results 26,051 infants were eligible for nirsevimab at birth. Overall uptake varied across infant, maternal, and hospital characteristics. Infants born to Spanish-speaking mothers (n = 2,270; 53.3%) and mothers who spoke a language other than English or Spanish (n = 247; 57.1%) had higher receipt compared to those of English-speaking mothers (n = 23,517; 40.5%, p < 0.001). Infants of Hispanic/Latina mothers (n = 5,716) were more likely to receive nirsevimab (48.3%) than those of non-Hispanic mothers (n = 20,335; 39.9%, p<.0001). Uptake was higher among urban infants (n = 11,976; 44.6%) than rural infants (n = 2,419; 31.7%, p<.0001). By birth weight, receipt was greatest among very low birth weight infants (1,000-1,499 g; n = 161; 82.0%) and lowest among large birth weight infants (≥4,000 g; n = 1,391; 37.8%, p<.0001). Similarly, uptake was highest among very preterm infants (28-31 weeks; n = 160; 78.1%) and lowest among post-term infants (≥42 weeks; n = 34; 14.7%, p<.0001). Hospital-level variation was evident, with uptake ranging from 10.3% (n = 78) to 53.3% (n = 3,011) across facilities (p<.0001). Conclusion These findings show clear disparities in nirsevimab distribution, suggesting groups for whom targeted efforts could increase uptake in the coming years.