Abstract: Influenza epidemic in the latest season in the USA is the most serious one in recent 10 years. And in China, the latest influenza epidemic is more serious than those in past 3 years. In this article, the authors briefly introduce the epidemics of influenza in both the USA and China and analyze the main causes of serious epidemic of influenza in the USA. Due to the important role of radiological examinations in the diagnosis and therapeutic efficacy assessment of influenza pneumonia, we also review the imaging demonstrations of type A influenza pneumonia, including the most common ground glass opacity and consolidation opacity and the common findings of lobular septal thickening and pleural effusion as well as cords like opacity after lesion absorption. The latest influenza epidemic indicates that promotion of influenza vaccination is necessary. Meanwhile, medical and health institutions of all levels should exert their own responsibilities and more health education campaigns are needed.

Key words: Influenza, Viral pneumonia, Emerging infectious diseases, Radiology of infectious diseases