Background: Respiratory syncytial virus (RSV) infections have a significant impact on public health, particularly among children and the elderly. However, the burden on the older adult population in Italy remains underestimated due to a lack of comprehensive data. Methods: Data on the molecular detection of respiratory syncytial virus (RSV) in respiratory samples from laboratories spanning the country from north to south between September 2021 and May 2023 were retrieved and were analysed. Results:Data from133,269 tests were provided by 13 laboratories across Italy, resulting in RSV positive rate of 6.3%. In adults aged 60 years and older (32.2% of the total), the overall RSV positive rate was 3.7%. The two waves of the epidemic peaked in December 2021 and January 2023, with the second wave having a higher number of cases.RSV subtyping showed that RSV-B was the most common type in both epidemic seasons, compared to RSV-A. Conclusion: In Italy, RSV infections pose a significant public health concern, with a higher prevalence than in the pre-Covid-19 scenario. Analyses of RSV circulation among older adults (OA) in Italy reveal seasonal variability and emphasise the importance of testing for RSV in this population. These findings could inform the surveillance and management of RSV infections, as well as the development of future prevention strategies.

Introduction: Human respiratory syncytial virus (RSV) is one of the most frequent causes of respiratory infections in children under five years of age, but its socio-economic impact and burden in primary care settings is still little studied. Methods: During the 2022/23 winter season, 55 pediatricians from five Italian regions participated in our community-based study. They collected a nasal swab for RSV molecular test from 650 patients under the age of 5 with Acute Respiratory Infections (ARIs) and performed a baseline questionnaire. The clinical and socio-economic burden of RSV disease in primary care was evaluated by two follow-up questionnaires completed by the parents of positive children, on day 14 and 30. Results: RSV laboratory-confirmed cases were 37.8% of the total recruited ARI cases, with RSV subtype B accounting for the majority (65.4%) of RSV-positive swabs. RSV-positive children were younger than RSV-negative ones (median 12.5 vs 16.5 months). The mean duration of symptoms for all children infected by RSV was 11.47 ± 6.27 days. We did not observe substantial differences in clinical severity between the two RSV subtypes, but RSV-A positive patients required more additional pediatric examinations than RSV-B cases. The socioeconomic impact of RSV infection was considerable, causing 53% of children to be absent from school, 46% of parents to lose working days and 25% of families to incur extra costs. Conclusions: Our findings describe a baseline of the RSV disease burden in primary care in Italy before the introduction of upcoming immunization strategies.

INTRODUCTION. Respiratory syncytial virus (RSV) is the major cause of lower respiratory tract illness in young children and can also cause influenza-like illness (ILI). Here we investigated the epidemiological features of RSV infection in pediatric ILI cases in Lombardy (a region in Northern Italy accounting nearly 10-million inhabitants) from 2014-2015 to 2020-2021 winter seasons. MATERIAL AND METHODS. Data for this study were retrieved and statistically analyzed from the database of virological influenza surveillance of the regional reference laboratory for Lombardy within the Italian influenza surveillance network (InfluNet). RESULTS. RSV accounting for nearly 19% of pediatric ILI with a risk of infection nearly 2-fold greater than that of individuals ≥15 years. The RSV positivity rate increased to 28% considering 0-5 years old children. Although in children ≤5 years the risk of infection from influenza viruses resulted nearly 2-fold higher than the risk of RSV infection, the age group 4-6 months and 7-12 months showed 5-fold greater risk of infection from RSV than from influenza. Children ≤5 years of age with presence of one or more comorbidities had a nearly 5-fold greater risk of getting RSV infection than otherwise healthy 0-5 years old children. DISCUSSION. The use of the ILI sentinel surveillance allowed us to identify groups at higher risk of RSV and influenza infection and to define the start, duration, timing and intensity of the RSV and influenza community circulation, determining thresholds based on historical data. This surveillance approach can be implemented to assess the nearly real-time RSV circulation and impact.