A single-center observational study of nirsevimab for prevention of RSV infection in preterm infants

Objective: This study aims to evaluate the clinical efficacy of nirsevimab in preventing respiratory syncytial virus (RSV) infection in preterm infants, highlighting its potential to improve neonatal respiratory health. Methods: We conducted a retrospective cohort study involving preterm infants admitted to the Neonatology Department of Inner Mongolia Maternity and Child Health Care Hospital between November 2024 and January 2026. The immunization group included infants receiving nirsevimab, while the non-immunized group was matched via propensity score matching. Both groups received standard care. Clinical data, as well as diagnostic and therapeutic processes, were collected. The efficacy and safety of nirsevimab were evaluated, and the incidence and severity of RSV-associated respiratory infections in two groups were followed up (severe cases were defined as those requiring respiratory support or experiencing adverse outcomes). Results: < 0.05). (2) In the non-immunized group, twelve preterm infants (15.18%) developed RSV-associated respiratory infections, among whom 4 cases (5.06%) required non-invasive ventilator support, 2 cases (2.53%) experienced myocardial injury, 1 case (1.26%) had liver injury, 1 case (1.26%) experienced myocardial injury combined with liver injury, and 1 case (1.26%) exhibited wheezing symptoms. (3) All preterm infants infected with RSV in the non-immunized group required rehospitalization, with an average hospital stay of 15.5 days; in contrast, no rehospitalization was required in the immunized group. (4) No significant adverse reactions were observed in the immunized group following nirsevimab injection. Conclusions: During the RSV epidemic season, our findings indicate that prophylactic treatment with nirsevimab significantly reduces the incidence of RSV infection in preterm infants, decreases the rehospitalization due to RSV infection in preterm infants, and demonstrates a favorable safety profile.