792 - Infant RSV immunoprophylaxis: A single center’s experience with early adoption of nirsevimab for all infant protection in Syracuse, New York

Publication Number: 792.5211

Holly Stacey, State University of New York Upstate Medical University, Syracuse, NY, United States; Ahmed Eltayeb, SUNY Upstate Medical University Hospital - - Syracuse, NY, syracuse, NY, United States; Kevin B. Hu, State University of New York Upstate Medical University, Syracuse, NY, United States; John J. Alfarone, State University of New York Upstate Medical University, Syracuse, NY, United States; Cara Smith, State University of New York Upstate Medical University, Syracuse, NY, United States; Ava Conklin, State University of New York Upstate Medical University, Syracuse, NY, United States; Steven Blatt, SUNY Upstate Medical, Syracuse, NY, United States; Joseph Domachowske, Upstate Golisano Children's Hospital, Syracuse, NY, United States; Danielle K. Daniels, Upstate Golisano Children's Hospital, Pennellville, NY, United States

Background: Passive immunoprophylaxis (IP) for infant protection against RSV infection first became available at the start of the 2023-2024 season.

Objective: We describe administration of RSV IP and disease burden among eligible patients in a hospital based pediatric clinic.

Design/Methods: We performed a single site retrospective chart review of infants eligible to receive RSV IP during the 2023-2024 RSV season. Pearson’s chi-square tests were performed to compare demographics and RSV burden by nirsevimab status. The study was approved by our local Institutional Review Board (IRB # 2172611).

Results: We identified 598 patients who were eligible to receive RSV IP. Of these, 295 (49%) received IP. The average age of administration was 74.4 days old (range: 0-406 days). The reason for not receiving nirsevimab was documented in 63% of records (Figure 1). A delay in routine vaccine administration was associated with not receiving nirsevimab (p < 0.001). Significant differences in ethnicity, insurance, and chronic medical conditions existed between those that received nirsevimab and those that did not (Table 1).

Infants who did not receive nirsevimab were more likely to be diagnosed (p < 0.001) and hospitalized for RSV (p=0.009). 50 of the 598 (8.4%) patients eligible to receive RSV IP developed a medically-attended RSV illness, 15 (30%) of whom were hospitalized; 4 (27%) required ICU care. The mean age for RSV-associated hospitalization was 11.6 weeks (range 1-51 weeks); 3 (20%) were born preterm. Among those hospitalized, only 2 (13%) had received nirsevimab and 1 was receiving monthly doses of palivizumab. 12/15 (80%) of hospitalized infants did not received either IP. 3 (11%) of the palivizumab eligible patients developed a medically-attended RSV infection. None had received RSV IP.

Among the 27 infants who met regional criteria for palivizumab, 1 (4%) received palivzumab alone, 4 (15%) received nirsevimab alone, and 13 (48%) received both. Only 2 infants were born to mothers who received RSV vaccine during pregnancy. Both were born at 40 wks GA; both also received nirsevimab.

Conclusion(s): Among this low-resource population, nirsevimab uptake was higher than the national average during the first available RSV season. 49% of eligible patients received one or more forms of protection despite the timing and restricted availability of both nirsevimab and maternal vaccine. 92% of infants were Vaccines for Children (VFC) eligible, thus improving access to nirsevimab. Education regarding safety and real-world effectiveness will be necessary to combat hesitancy and optimize immunization rates during future RSV seasons.

Documented reasons for not receiving nirsevimab
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Demographics and RSV disease burden among RSV IP eligible patients during the 2023-2024 RSV season
Slide1.jpegPearson’s chi-square tests were performed to compare demographics and RSV disease burden between those who received nirsevimab and those who did not. The Child Opportunity Index (COI) score is a composite score that measures opportunity in neighborhoods within the United States from 1 to 100.