Abstract
Respiratory Syncytial Virus (RSV) is a prevalent pathogen of the respiratory tract, posing a significant threat to individuals with compromised immune systems, particularly the elderly and neonates in hospital settings. The primary objective of this study was to identify a specific period within the epidemic season during which healthcare providers can anticipate an increased incidence of RSV infections and characterize the epidemic season in Poland. Molecular biology techniques were employed to diagnose samples at Sanitary Stations and the National Institute of Public Health (NIC) in Warsaw. Epidemiological data were collected using the SENTINEL surveillance system. In the 2020/2021 season, there were no reported cases of RSV due to the prioritization of SARS-CoV-2 diagnostics. Before the pandemic, the period of heightened RSV infection risk typically commenced in the 51st week or later, with a statistically significant correlation indicating that a later start was associated with a shorter season duration (p = 0.034). In post-pandemic seasons, the temporal distribution of RSV cases exhibited a notable shift, with earlier season onset, peak, and conclusion. Data indicate that RSV is predominantly diagnosed in pediatric populations; however, since the 2017/2018 season, there has been an increase in RSV diagnoses among other age groups. Given the observed shifts in the seasonal peak following the SARS-CoV-2 pandemic, ongoing surveillance is required to ascertain whether these changes are permanent or transient.