20世纪出现了3次流感大流行,分别由A型流感病毒H1N1、H2N2和H3N2三种不同的抗原亚型引起,其中1957年和1968年的两次流行发生在现代病毒学时代,流感病毒的特征得到了系统的研究。流感流行事件表明流感大流行在时间和形式上是不可预测的。有证据显示流感大流行主要是由人流感病毒与动物A型流感病毒的基因重排而产生新血凝素亚型的病毒引起。 Three influenza pandemics occurred in the 20th century, which were caused by three different subtypes of influenza A H1N1, H2N2 and H3N2, respectively. The two epidemics in 1957 and 1968 occurred in the era of modern virology. Influenza viruses The characteristics have been systematically studied. Influenza pandemic events indicate that the influenza pandemic is unpredictable in time and in form. There is evidence that the influenza pandemic is caused primarily by viruses that produce neohemagglutinin subtypes through genetic rearrangement of human and influenza A viruses.