Comparative virulence of seasonal viruses responsible for lower respiratory tract infections: a southern European multi-centre cohort study of hospital admissions.

Objectives: Our study aimed to compare the clinical severity of lower respiratory tract infections (LRTI's) caused by Influenza and Respiratory Syncytial Virus (RSV).

Methods: We conducted a retrospective cohort study of LRTI admissions with positive PCR results for Influenza or RSV from 2017 to 2019 in three teaching hospitals in southern Europe. Data on clinical characteristics, viral agents and disease outcome were collected.