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

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

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

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.

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.

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