Epidemiological and virological surveillance of Severe Acute Respiratory Infections in the 2019/2020 season in Siena, Tuscany, Italy

Background: Influenza is a major public health issue. Indeed, in Italy there were 7.6 million symptomatic cases of influenza in the 2019/2020 influenza season (from October 2019 to April 2020). We analysed influenza A and B viruses in hospitalized adult and elderly patients with Severe Acute Respiratory Infections (SARI) at Le Scotte University Hospital in Siena. Methods: Oropharyngeal swabs were taken from 68 SARI patients, who also completed a questionnaire recording their underlying diseases and vaccination status. Total RNA was extracted from each respiratory swab by means of the QIAamp Viral RNA Mini kit, and RT-PCR was carried out. All statistical analyses were performed by means of GraphPad Prism 6 software and STATA. Results: The average age of subjects was 79.4 years (C.I.: 76.6-82.3) and 52.9% were female. The subjects had fever (89.7%), fatigue (77%), headache (47%), cough (75%), sore throat (70.5%), and breathlessness (63.2%). We found that 20% of the 68 subjects were positive (13% for A H3N2 and 7% for A H1N1). Of the 68 subjects, 25% had received a seasonal influenza vaccine (91.6% trivalent and 8.4% quadrivalent). Conclusions: The virological surveillance of influenza is important in order to determine the timing and spread of influenza viruses and track changes in circulating influenza viruses, so as to inform seasonal influenza vaccine composition. SARI surveillance has been implemented in the European Region since 2009. Seasonal vaccination is considered the most effective way to prevent influenza and its complications