Respiratory viral infections before the COVID-19 in Portugal: A single center study.

Objectives: We aimed to describe the respiratory viruses (RV) found in respiratory samples from patients admitted to Hospital de São Bernardo, Setúbal, Portugal, between October 2019 and March 2020, and to correlate these with clinical features. Design: This retrospective study explored 948 fresh frozen naso/oropharyngeal swabs, tested by reverse transcription-polymerase chain reaction. Results: Rhinovirus/enterovirus, influenza, and respiratory syncytial virus (hRSV) were the most prevalent RV. Half of the patients fulfilled the acute respiratory infection (ARI) and/or influenza-like illness (ILI) criteria, with increasing age significantly reducing the risk of ARI and/or ILI. Hospital admission was more frequently observed in symptomatic patients, but the length of stay and mortality were significantly lower. Most (96.5 %) patients had a main respiratory diagnosis. In adults, the most prevalent was pneumonia, which particularly affected older patients, while in children, the most common was bronchiolitis. The number of hospital admissions was high. Sudden onset, shortness of breath, older age, and hRSV detection significantly increased the risk of hospital admission overall. In bronchiolitis, female gender significantly increased the risk of hospital admission, while older age significantly reduced this risk. Twenty patients died within the first month of sampling, and all were older adults. Older age and male gender significantly increased the risk of death. Conclusions: Respiratory viral infections can have a significant clinical impact, particularly in young infants with bronchiolitis and older adults with pneumonia. This study provides the first snapshot of the respiratory viral infections just before the outbreak of SARS-CoV-2 in Portugal, providing relevant clinical insights.