Clinical Profile and Outcomes of Respiratory Syncytial Virus Compared with Other Viral Infections in Hospitalized Term Infants: A Prospective Multicenter Study

Background: Acute respiratory infections (ARIs) are a leading cause of infant morbidity and hospitalization, with respiratory viruses being the predominant etiological agents. Data on clinical profile and outcomes of viral ARIs in term infants from India remain limited. Our objective was to evaluate the epidemiology, clinical profile, laboratory profile, and outcomes of respiratory syncytial virus (RSV) and other viral ARIs in hospitalized infants (aged ≤ 12 months) born at term (>37 weeks gestation). Methods: This prospective, multicenter, hospital-based observational study was conducted in Eastern India between July 2023 and March 2025. Respiratory viruses were detected using real-time RT-PCR. Demographic, clinical, laboratory, radiological, treatment, and outcome data were analyzed. RSV-positive infants were compared with RSV-negative infants and with infants infected with other respiratory viruses. Results: Among 224 infants, respiratory viruses were detected in 56.3%, with RSV being the most common pathogen (19.6%). Compared with infants infected with other respiratory viruses, RSV-positive infants had a significantly higher frequency of fast breathing (72.7% vs. 53.6%, p = 0.03), higher levels of inflammatory markers, and a longer median hospital stay (8 vs. 6 days, p = 0.02). In exploratory multivariable analysis, RSV infection (adjusted OR [aOR] 2.4, 95% CI 1.3–6.1), low-flow oxygen requirement at admission (aOR 1.9, 95% CI 1.4–5.3), and feeding difficulty (aOR 1.3, 95% CI 1.0–2.9) were independently associated with severe disease. Conclusions: RSV was the leading viral cause of ARI in hospitalized term infants and was associated with greater respiratory involvement, a heightened inflammatory response, and prolonged hospitalization compared with other viruses. These findings highlight the importance of early recognition and appropriate supportive care in hospitalized term infants with RSV infection.