Seasonal Prevalence of Influenza, RSV, and SARS-CoV-2 Among ARI and SARI Patients in a Tertiary Hospital, West Bengal, 2025

Background: Respiratory viruses such as Influenza, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and respiratory syncytial virus (RSV) remain major global health concerns causing acute respiratory infection and severe acute respiratory infection (ARI and SARI) with overlapping clinical presentations and seasonal co-circulation. These are a leading cause of morbidity and mortality, making identification and burden assessment across all age groups critical and essential. Aims and Objectives: The present study was undertaken to estimate the prevalence, seasonal trends, and age-wise distribution of Influenza, RSV, and SARS-CoV-2 among ARI and SARI patients in a tertiary care hospital in Kolkata, West Bengal and to identify the predominant circulating subtypes during the surveillance period. Materials and Methods: A hospital-based observational study was conducted at viral research and diagnostic laboratories (VRDL), Department of Microbiology from January 2025 to January 2026. Nasopharyngeal and oropharyngeal swabs were collected from symptomatic individuals in outpatient department, in-patient department, and community Center. Detection of Influenza, RSV along with their subtypes and SARS-CoV-2 was performed using BioRad platform with Indian Council of Medical Research-National Institute of Virology multiplex reverse transcription polymerase chain reaction assay kit. Results: Of 1329 samples, 58 (4.36%) were Influenza positive, 82 (6.17%) RSV positive, and 3 (0.23%) SARS-CoV-2 positive. Influenza B (55.17%) cases were more than Influenza A (44.83%). All Influenza A cases were H3N2 and noH1N1 was detected. RSV infections were high, peaking in August–September, indicating a seasonal shift. Most casesoccurred between May and October with 48.7% SARI and 51.3% ARI cases. Overall mortality remained low (0.8%). Conclusion: Early identification of respiratory viruses enables timely antiviral therapy, reduces unnecessary antibiotic use, and informs public health interventions. The study highlights the importance of VRDL-based surveillance for accurate and early detection and monitoring of the respiratory viruses.