Department for Infectious Disease Epidemiology, Robert Koch Institute, DGZ-Ring 1, 13086 Berlin, Germany.
BMC Infect Dis. 2010 Jun 7;10:155. doi: 10.1186/1471-2334-10-155.
The first imported case of pandemic influenza (H1N1) 2009 in Germany was confirmed in April 2009. However, the first wave with measurable burden of disease started only in October 2009. The basic epidemiological and clinical characteristics of the pandemic were analysed in order to understand the course of the pandemic in Germany.
The analysis was based on data from the case-based, mandatory German surveillance system for infectious diseases. Cases notified between 27 April and 11 November 2009 and fulfilling the case definition were included in the study.
Two time periods with distinct epidemiologic characteristics could be determined: 23,789 cases (44.1%) occurred during the initiation period (IP, week 18 to 41), and 30,179 (55.9%) during the acceleration period (AP, week 42 to 45). During IP, coinciding with school summer holidays, 61.1% of cases were travel-related and one death occurred. Strict containment efforts were performed until week 32. During AP the majority of cases (94.3%) was autochthonous, 12 deaths were reported. The main affected age group shifted from 15 to 19 years in IP to 10 to 14 years in AP (median age 19 versus 15 years; p < 0.001). The proportion of cases with underlying medical conditions increased from 4.7% to 6.9% (p < 0.001). Irrespective of the period, these cases were more likely to be hospitalised (OR = 3.6 [95% CI: 3.1; 4.3]) and to develop pneumonia (OR = 8.1 [95% CI: 6.1; 10.7]). Furthermore, young children (0 to 2 years) (OR = 2.8 [95% CI: 1.5; 5.2]) and persons with influenza-like illness (ILI, OR = 1.4 [95% CI: 1.0; 2.1]) had a higher risk to develop pneumonia compared to other age groups and individuals without ILI.
The epidemiological differences we could show between summer and autumn 2009 might have been influenced by the school summer holidays and containment efforts. The spread of disease did not result in change of risk groups or severity. Our results show that analyses of case-based information can advise future public health measures.
德国首例 2009 年大流行性流感（H1N1）病例于 2009 年 4 月确诊。然而，仅在 2009 年 10 月才开始出现可衡量疾病负担的第一波疫情。为了了解德国大流行的进程，对大流行的基本流行病学和临床特征进行了分析。
该分析基于传染病基于病例的强制性德国监测系统的数据。纳入了 2009 年 4 月 27 日至 11 月 11 日期间符合病例定义的病例。
可以确定两个具有明显流行病学特征的时间段：23789 例（44.1％）发生在启动期（第 18 周至 41 周），30179 例（55.9％）发生在加速期（第 42 周至 45 周）。在启动期恰逢学校暑假，61.1％的病例与旅行有关，有 1 例死亡。严格的遏制措施一直持续到第 32 周。在加速期，大多数病例（94.3％）是本地发生的，报告了 12 例死亡。主要受影响的年龄组从启动期的 15 至 19 岁转移到加速期的 10 至 14 岁（中位数年龄为 19 岁对 15 岁；p <0.001）。有基础疾病的病例比例从 4.7％增加到 6.9％（p <0.001）。无论在哪个时期，这些病例住院的可能性更大（OR = 3.6 [95％CI：3.1; 4.3]），并且更容易发生肺炎（OR = 8.1 [95％CI：6.1; 10.7]）。此外，幼儿（0至 2 岁）（OR = 2.8 [95％CI：1.5; 5.2]）和流感样疾病（ILI）患者（OR = 1.4 [95％CI：1.0; 2.1]）与其他年龄组和无 ILI 的个体相比，患肺炎的风险更高。
我们在 2009 年夏季和秋季之间显示的流行病学差异可能受到学校暑假和遏制措施的影响。疾病的传播并没有改变风险群体或严重程度。我们的研究结果表明，基于病例信息的分析可以为未来的公共卫生措施提供建议。
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