Comparison of hospitalized patients with severe pneumonia caused by COVID-19 and influenza A (H7N9 and H1N1): A retrospective study from a designated hospital.

Considerable attention has been focused on the clinical features of coronavirus disease 2019 (COVID-19), but it is also important for clinicians to differentiate it from influenza virus infections. In the present study, the rate of coexisting disease was lower in the severe COVID-19 group than in the influenza A group ( = 0.003). Radiologically, severe COVID-19 patients had fewer instances of pleural effusion ( < 0.001). Clinically, severe COVID-19 patients had relatively better disease severity scores, less secondary bacterial infections, shorter times to beginning absorption on computed tomography, but longer durations of viral shedding from the time of admission ( < 0.05). Although the more severe influenza A patients required noninvasive respiratory support, these two groups ultimately yielded comparable mortalities. Based on the multiple logistic regression analysis, severe COVID-19 infection was associated with a lower risk of severe acute respiratory distress syndrome [odds ratio (OR) 1.016, 95% [confidence interval (CI)] 1.001-1.032, = 0.041] and a better pneumonia severity index (OR 0.945, 95% [CI] 0.905-0.986, = 0.009); however, these patients exhibited longer durations of viral shedding (OR 1.192, 95% [CI] 1.047-1.357, = 0.008) than patients with severe influenza A infection. In conclusion, the conditions of severe influenza A patients appeared to be more critical than that of severe COVID-19 patients. However, relatively lower mortalities of these two severe cases are expected in the context of sufficient medical supplies.