Epidemiologic characterization of the 1918 influenza pandemic summer wave in Copenhagen: Implications for pandemic control strategies
Epidemiologic characterization of the 1918 influenza pandemic summer wave in Copenhagen: Implications for pandemic control strategies
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DOI：
10.1086/524065
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发表时间：
2008-01-15
影响因子：
6.4
通讯作者：
Simonsen, Lone
中科院分区：
文献类型：
--
作者：
Andreasen, Viggo;Viboud, Cecile;Simonsen, Lone
背景1918年至1919年的A/H1N1流感大流行在全世界造成约5000万人死亡。历史记录表明，1918年夏天，早期的大流行浪潮袭击了欧洲。我们获得了1910-1919年期间在丹麦哥本哈根每周汇编的监测数据;记录包括医学治疗的流感样疾病（ILI）、住院和按年龄划分的死亡。我们使用Serfling季节性回归模型来量化超额发病率和死亡率，并估计夏季、秋季和冬季大流行波的生殖数（R）。1918年夏天，哥本哈根发生了一场大规模的流行病;死亡人数的年龄分布是1918-1919年甲型H1N1流感大流行的总体特征。1918年，夏季的流感浪潮占所有过剩的ILI和住院病例的29%-34%，而病死率（0.3%）比秋季的流感浪潮（2.3%）低许多倍。在其他3个斯堪的纳维亚城市也观察到类似的情况。在所有城市中，夏季（2.0-5.4）的R显著高于秋季（1.2-1.6）。哥本哈根夏季的流感浪潮可能是由一种前体甲型H1N1流感病毒引起的，这种病毒传播效率高，但缺乏极端的毒性。在夏季波中测量的R可能是完全易感人群中传播率的更好近似值，并且远高于以前美国研究中发现的值。夏季的海浪可能对致命的秋季海浪提供了部分保护。
Background. The 1918-1919 A/H1N1 influenza pandemic killed similar to 50 million people worldwide. Historical records suggest that an early pandemic wave struck Europe during the summer of 1918.Methods. We obtained surveillance data that were compiled weekly, during 1910-1919, in Copenhagen, Denmark; the records included medically treated influenza-like illnesses (ILIs), hospitalizations, and deaths by age. We used a Serfling seasonal regression model to quantify excess morbidity and mortality, and we estimated the reproductive number (R) for the summer, fall, and winter pandemic waves.Results. A large epidemic occurred in Copenhagen during the summer of 1918; the age distribution of deaths was characteristic of the 1918-1919 A/H1N1 pandemic overall. That summer wave accounted for 29%-34% of all excess ILIs and hospitalizations during 1918, whereas the case-fatality rate (0.3%) was many-fold lower than that of the fall wave (2.3%). Similar patterns were observed in 3 other Scandinavian cities. R was substantially higher in summer (2.0-5.4) than in fall (1.2-1.6) in all cities.Conclusions. The Copenhagen summer wave may have been caused by a precursor A/H1N1 pandemic virus that transmitted efficiently but lacked extreme virulence. The R measured in the summer wave is likely a better approximation of transmissibility in a fully susceptible population and is substantially higher than that found in previous US studies. The summer wave may have provided partial protection against the lethal fall wave.