RSV in older adults: a prospective multicentric cohort study in the primary care setting in Italy

Abstract Background Respiratory syncytial virus (RSV) is increasingly recognized as a cause of acute respiratory infections (ARIs) in older adults, yet its impact in primary care remains underappreciated. We conducted a multicenter study across four Italian regions to characterize RSV infection in older adults. Methods Between 2022 and 2024 winter seasons, we enrolled adults aged 60+ years who presented with ARI to participating general practitioners (GPs). At enrollment (T0), each patient provided a nasopharyngeal swab for multiplex RT-PCR testing. Those who tested positive for RSV were then followed up by telephone at 14 days (T14) and 30 days (T30) to record health status, treatments, and any hospital or emergency department (ED) visits. Results A total of 664 ARI patients were recruited, of whom 88(13%) were RSV-positive. The proportion of RSV cases declined, from 33/152 (22%) in 2022-23 to 15/126 (12%) in 2023-24 and 40/386 (10%) in 2024-25. Among RSV+ patients, the median age was 74 years (IQR 67-80). RSV B was the predominant subtype (69%), and 36% of RSV cases had at least one co-infection, most commonly H. influenzae (18%). At T0, the overall cohort of ARI patients most commonly reported coryza (69%), fatigue (59%), and productive cough (59%), with only 31% having fever. Among RSV+ patients, a different pattern was observed: coryza (77%), productive cough (62%), fatigue (53%), and fever (35%). 77(88%) RSV patients completed both follow-up interviews. Median RSV illness duration was 24 days (IQR 15-34). By day 30 post-enrollment, 57/77 (74%) had re-contacted their GP, 3/77 (4%) had visited the ED, and 2/77 (3%) had been hospitalized. Conclusions RSV significantly contributes to the burden of ARIs in Italian adults aged 60 and over, with prolonged illness durations and substantial healthcare utilization. The recent availability of RSV vaccines for older adults underscores the importance of implementing targeted immunization strategies to mitigate this burden. Key messages • Respiratory syncytial virus (RSV) is a common cause of acute respiratory infection in adults aged 60 and above, with a prolonged illness duration requiring multiple contacts with general practitioners. • Fever as a symptom is not highly prevalent in laboratory-confirmed respiratory syncytial virus (RSV) acute respiratory infection cases in adults aged 60 and above.