[Clinical and epidemiological differences and similarities of viral pneumonias in two pandemics].

Background: In a decade, we faced two pandemic viruses, influenza A H1N1pdm09 and SARS CoV-2, whose most serious manifestation is pneumonia.

Aim: To compare the clinical, epidemiological and management aspects of pneumonias caused by each pandemic virus in adults requiring hospitalization.

Material And Methods: Comparative, observational study carried out at a regional Chilean hospital, including 75 patients with influenza A H1N1pdm09 prospectively studied in 2009 and 142 patients with SARS-CoV-2 studied in 2020.

Results: Patients with SARS-CoV-2 pneumonia were older (56 and 39.7 years respectively, p < 0.01) and had significantly more comorbidities. Cough, fever and myalgias were more frequent in influenza. Dyspnea was more frequent in COVID-19. Patients with COVID-19 had more extensive lung involvement and a longer hospitalization (13.6 and 8.6 days respectively, p = 0.01). There was no difference on ICU admission requirements and mortality attributable to pneumonia. Patients with influenza had greater APACHE scores and a higher frequency of a PaO2/FiO2 ratio ≤ 200. During COVID-19pandemic chest sean replaced x-ray examination. Also high-flow nasal cannulas and awake prone position ventilation were added as treatments.

Conclusions: COVID-19 patients were older, had fewer classic flu symptoms but more dyspnea and longer hospitalization periods than patients with influenza.