Tehran University of Medical Sciences Iranian Journal of Microbiology 2008-3289 18 3 2026 06 07 367 374 EN Forough Tavakoli Department of Bacteriology and Virology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran Sharareh Moghim Department of Bacteriology and Virology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran Vahid Salimi Department of Virology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran Mohammad Ali Pourmirzaiee Department of Pediatrics, Research Institute for Primordial Prevention of Non-Communicable Disease, Child Growth and Development Research Center, Isfahan University of Medical Sciences, Isfahan, Iran 2025 12 07 2026 02 14 Background and Objectives: Respiratory syncytial virus is the most common virus causing acute respiratory infections in children under 5 years old. We aimed to investigate the prevalence and circulating strains of RSV in hospitalized children in Isfahan. Materials and Methods: Between January and May 2024, children under 5 years of age were enrolled in this study. Nasal swabs were collected from 100 children with acute respiratory infections admitted to the referral pediatric ward at Imam Hossein Children’s Hospital in Isfahan, Iran. The prevalence of circulating RSV was investigated using the RSV qPCR detection kit. The virus type was identified by RT-PCR using type A- and B-specific primers. Results: A total of 51 (51%) samples tested positive for RSV. Among them, typing was done in 33 specimens, of which 66.6% (22/33 cases) were assigned as subtype B and 33.3% (11/33 cases) as subtype A. Infants under 6 months were most severely affected by RSV (47.1%, 24/51). RSV-positive samples peaked in February (43.1%), followed by January (29.4%). Conclusion: The results of the current study revealed a high prevalence of RSV and co-circulation of subtypes A and B, with subtype B more prevalent among children. This highlights the importance of ongoing surveillance of RSV. https://ijm.tums.ac.ir/index.php/ijm/article/view/5992 https://ijm.tums.ac.ir/index.php/ijm/article/download/5992/1896