To explore the different clinical and CT features distinguishing COVID-19 from H1N1 influenza pneumonia.

COVID-19 pneumonia patients showed less proportions of underlying diseases, fever and respiratory symptoms than those of H1N1 pneumonia patients (p<0.01). White blood cell count, neutrophilic granulocyte percentage, C-reactive protein, procalcitonin, D-Dimer and lactate dehydrogenase in H1N1 pneumonia patients were higher than those of COVID-19 pneumonia patients (p<0.05). H1N1 pneumonia were often symmetrically located in the dorsal part of lung inferior lobes, while COVID-19 pneumonia were unsually showed a peripheral but non-specific lobe distributions. Ground glass opacity was more common in COVID-19 pneumonia and consolidation lesions was more common in H1N1 pneumonia (p<0.01). COVID-19 pneumonia lesions showed a relative clear margin compared with H1N1 pneumonia. Crazy-paving pattern, thickening vessels, reversed halo sign and early fibrotic leisions were more common in COVID-19 pneumonia than H1N1 pneumonia (p<0.05). Pleural effusion in COVID-19 pneumonia was significantly less common than H1N1 pneumonia (p<0.01).

Compared with H1N1 pneumonia in Zhejiang, China, the clinical manifestations of COVID-19 pneumonia was more concealed with less underlying diseases and slighter respiratory symptoms. The more common CT manifestations of COVID-19 pneumonia included ground glass opacity with a relative clear margin, crazy-paving pattern, thickening vessels, reversed halo sign and early fibrotic leisions, while the less common CT manifestations of COVID-19 pneumonia included consolidation and pleural effusion.

Inclusion Criteria:

• pneumonia

Exclusion Criteria:

• no pneumonia

pneumonia with COVID-19 pneumonia or H1N1 influenza