Department of Infection and Immunity, Faculty of Medicine, The University of Sheffield, Sheffield S10 2RX, UK.
J Infect. 2011 Oct;63(4):252-9. doi: 10.1016/j.jinf.2011.04.013. Epub 2011 May 12.
To analyse the records of past influenza outbreaks to determine a definition for pandemics.
Analysis of publications of large outbreaks of influenza which have occurred since 1889/90, and to match the results against the current definitions of an influenza pandemic.
According to the general understanding of a pandemic, nine outbreaks of influenza since 1889/90 satisfy the definition; however, for two of these, occurring in 1900 and 1933, the data are limited. The special condition for an influenza pandemic requires, in one definition, that the virus strain responsible could not have arisen from the previous circulating strain by mutation; and in the second, that the new strain be a different subtype to the previously circulating strain. Both these restrictions deny pandemic status to two, and possibly three, influenza outbreaks which were pandemics according to the more general understanding of the term. These observations suggest that a re-evaluation of the criteria which define influenza pandemics should be carried out.
The contradiction outlined above brings the previous definitions of an influenza pandemic into question; however, this can be resolved by defining an influenza pandemic by the following criteria. Thus, an influenza pandemic arises at a single, specific place and spreads rapidly to involve numerous countries. The haemagglutinin (HA) of the emergent virus does not cross-react serologically with the previously dominant virus strain(s), and there is a significant lack of immunity in the population against the emergent virus. These three criteria are interlinked and can be determined early to alert authorities who could respond appropriately. Other criteria associated with pandemics are necessarily retrospective, although important and valid. The implications of this definition are discussed.
分析过去流感大流行的记录，确定大流行的定义。
分析自 1889/90 年以来发生的大流感暴发的文献，并将结果与当前流感大流行的定义相匹配。
根据大流行的一般理解，自 1889/90 年以来发生的九次流感暴发符合定义；然而，对于其中两次，即 1900 年和 1933 年发生的暴发，数据有限。流感大流行的特殊条件要求，在一种定义中，负责的病毒株不能由前一轮流行株的突变产生；而在另一种定义中，新株必须与前一轮流行株的亚型不同。这两种限制都否认了两种流感大流行的大流行地位，可能还有三种，根据该术语的更广泛理解，这两种流感大流行都是大流行。这些观察结果表明，应该对定义流感大流行的标准进行重新评估。
上述矛盾使以前的流感大流行定义受到质疑；然而，通过以下标准定义流感大流行可以解决这个问题。因此，流感大流行在一个特定的地点突然发生，并迅速传播到许多国家。出现的病毒的血凝素（HA）在血清学上与以前占主导地位的病毒株不发生交叉反应，人群中对出现的病毒存在显著缺乏免疫力。这三个标准是相互关联的，可以早期确定，提醒当局采取适当的应对措施。与大流行相关的其他标准必然是回顾性的，尽管它们很重要且有效。讨论了这一定义的含义。
