RSV epidemiology in Italian adults over 60: a multicenter cross-sectional study

Objective: Respiratory syncytial virus (RSV) infections have a significant impact on public health, particularly among children and the elderly. However, the burden on older adults in Italy is underestimated due to a lack of comprehensive data. Methods: Data on the molecular detection of RSV in respiratory samples from laboratories across Italy, from north to south, between September 2021 and May 2023 were collected and analyzed. Results: A total of 138,783 tests were provided by 13 laboratories, with an overall RSV positivity rate of 6.4 %. Among adults aged ≥60 years (35.4 % of the total), the RSV positivity rate was 3.5 %. Two epidemic waves were observed, peaking in December 2021 and January 2023, with the second wave showing a higher number of cases. RSV subtyping revealed that RSV-B was the predominant subtype in both epidemic seasons, compared to RSV-A. Conclusion: Analyses of RSV circulation in older adults highlight seasonal variability and underscore the importance of testing in this population. These findings may inform surveillance, clinical management, and the development of future preventive strategies, including vaccination.