Background Acute Respiratory Infections (ARIs) have a relevant impact on public health in terms of prevalence and costs associated with the diseases. Since COVID-19 pandemic highlighted the need to adopt accurate surveillance systems to face new emergencies, the aim of our work is to describe the impact of ARIs on healthcare facilities. s. Methods A retrospective analysis was conducted on electronic medical records from Pisa University Hospital, from January 2017 to December 2021. To link ED admissions and lab test, multiple linear regression models were used to understand the phenomenon and to assess the contribution of each virus within different age groups. Results During the study period, 33,101 ARI admissions in ED were registered, resulting in 7,426 hospital admissions. We observed a seasonal pattern between week 42 of each year and week 17 of the following year. A reduction in ED admissions has been found in 2020, while, the average weekly rate was of 30.8% in 2020, as compared with 21.7% in 2017-2019. Analysis by age group showed a peak of accesses in the last weeks of 2021 for the <1 and 1-4 years old. Conclusions Data on ARI-related admissions provide valuable insights into the dynamic patterns of seasonal air-borne infections and specific age-related vulnerabilities. This could be useful in directing health policies to identify indicators of future epidemic waves. These findings contribute to the ongoing efforts to enhance preparedness and response strategies for respiratory infections, laying the groundwork for more effective public health interventions in the future.

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.