OBJECTIVES: Respiratory Syncytial Virus (RSV) is a major cause of severe respiratory illnesses in infants, presenting significant public health challenges in Paraguay. RSV is the leading cause of hospitalizations among infants, with most hospitalizations occurring in healthy, full-term infants, although prematurity also represents a risk condition.This study evaluates the public health impact and related cost of nirsevimab implementation versus current clinical practice for preventing RSV in infants from the perspective of Paraguay’s public healthcare system.

METHODS: A static decision-analytic model was used to assess monthly cohorts of infants under one year old over a one-year period, capturing RSV-related health outcomes and costs of hospitalisation, ICU admission, mechanical ventilation, emergency visits, and outpatient visits. The model considered the seasonal distribution of RSV cases and the age at immunization. The analysis included highrisk preterm infants, preterm infants not eligible for palivizumab, and term infants, using efficacy data from the Ph2b, MELODY, and HARMONIE studies. A universal immunization strategy with nirsevimab was compared to the standard of care (SoC), which uses palivizumab for high-risk infants.

RESULTS: Under the SoC, RSV leads to 5,333 hospitalizations, 1,338 ICU admissions, 278 cases requiring mechanical ventilation, 12,544 emergency visits, and 36,559 outpatient visits, totalling USD$34 million in costs. Nirsevimab implementation reduces health events compared to SoC, preventing 2,330 hospitalizations, 623 ICU admissions, 129 cases requiring mechanical ventilation, 4,998 emergency visits, and 14,803 outpatient visits. Nirsevimab results in cost savings of USD$7.5 million in hospitalizations, USD$2 million in ICU admissions, USD$1.4 million in mechanical ventilation, USD$3 million in emergency visits, and USD$700,000 in outpatient visits.

CONCLUSIONS: The findings support including nirsevimab in the national immunization program, highlighting its potential to reduce the healthcare and economic burden of RSV in Paraguay, thereby justifying its implementation.