# P-485. Healthcare-associated Respiratory Syncytial Virus (RSV) Infection During Prolonged Birth Hospitalization: Is There a Role for Nirsevimab?

## TL;DR

The study examines healthcare-associated RSV infections in infants during birth hospitalization and evaluates the potential role of nirsevimab in prevention.

## Contribution

The study provides insights into the frequency of healthcare-associated RSV in infants and assesses the potential impact of nirsevimab administration timing.

## Key findings

- From 2012 to 2024, 76 healthcare-associated RSV infections occurred in infants under 2 years, with 18 (24%) during birth hospitalization.
- None of the 18 infants had received RSV immunoprophylaxis, and no deaths were reported.
- Use of nirsevimab could prevent some healthcare-associated RSV cases but would require immunizing many infants.

## Abstract

On 8/3/2023, the CDC/Advisory Committee on Immunization Practices recommended nirsevimab, a long-acting monoclonal antibody, for prevention of RSV-associated lower respiratory tract infection in all infants aged < 8 months and some high-risk young children aged 8-19 months. At Nationwide Children’s Hospital (NCH; 673 beds) and its 7 affiliated NICUs ( > 3,000 admissions/year) in Columbus, OH, infants with prolonged birth hospitalization related to prematurity or other causes receive nirsevimab shortly before hospital discharge. Earlier use of nirsevimab for prevention of healthcare-associated (HA) RSV disease was not recommended. However, HA-RSV disease is associated with substantial morbidity and occasional mortality, mainly in children with underlying medical conditions. Our objective was to determine the magnitude and review the cases of HA-RSV infections at NCH and its NICUs in order to inform guidance on timing of nirsevimab administration.Healthcare-associated RSV infections during the birth hospitalization of 18 infants and young children <2 years of age

Healthcare-associated RSV infections during the birth hospitalization of 18 infants and young children <2 years of age

Retrospective analysis of prospectively obtained surveillance data of all HA-RSV infections that occurred during infants’ birth hospitalization. RSV PCR testing in infants who developed respiratory symptoms was at the discretion of the attending physician.

From 2012 to 2024, there were 76 cases of HA-RSV infections in infants and children < 2 years of age. Of the 76 cases, 18 (24%) occurred among infants during the birth hospitalization for a median of 1-2 cases/year with a range of 1 to 7 infants per year (Fig 1). Median (IQR) chronologic age at the time of the HA-RSV infection was 1.7 (0.8-3.5) months. 72% (13/18) of infants (gestational age, 22 to 40 wks; birth weight, 550 to 3590 g) were in the NICU (10, preterm; 4, BPD; 3, genetic disorder) while 2 (gestational age, 39 and 37 wks; birth weight, 3145 g and 3200 g) were in the Cardiothoracic-ICU (1, transposition of the great arteries, s/p SWITCH; 1, cardiomyopathy, pulmonary hypertension, s/p ECMO). None of the infants had received RSV immunoprophylaxis and none died.

HA-RSV disease was infrequent among infants during the birth hospitalization. Use of nirsevimab in addition to traditional infection prevention and control strategies would have resulted in immunization of many infants in order to prevent few HA-RSV cases.

Cristina Tomatis Souverbielle, MD, Merck inc: Research support, isp Asuncion Mejias, MD, PhD, MsCS, Enanta: Advisor/Consultant|Merck: Grant/Research Support|Moderna: Advisor/Consultant|Pfizer: Advisor/Consultant|Sanofi-Pasteur: Advisor/Consultant