Influenza is a highly infectious viral disease, characterized by fever, headache, muscle ache, runny nose, cough and sore throat. The incubation period for influenza is usually about 1-3 days.

• 流行性感冒（简称流感）是一种传染性极高的病毒性疾病。徵状包括发烧、头痛、肌肉疼痛、流鼻水、咳嗽及喉咙痛。流感的潜伏期通常约为一至三日。