BACKGROUND
Germany experienced one of the lowest COVID-19 case-fatality rates (CFRs) in Western Europe in the first pandemic wave, and further CFR decreases in the spring and summer of 2020. However, Germany’s CFR increased markedly during the second wave, becoming one of the highest in Western Europe. Furthermore, CFRs varied considerably across German federal states. The drivers of this CFR time trend and the state differences remain unclear.

OBJECTIVE
We aim to identify the contribution to the CFR differences across and within German states of (1) the population age structure, (2) the age structure of confirmed infection rates, and (3) the age-specific fatality.

METHODS
We use data documenting COVID-19 cases and deaths from the COVerAGE-DB, applying demographic decomposition methods proposed by Kitagawa and Horiuchi.

RESULTS
The CFR decrease between spring and autumn 2020 in Germany resulted from a shift toward younger ages in confirmed infection rates and decreasing age-specific fatality. The CFR increase that followed was predominantly driven by a shift toward older ages in the age composition of confirmed infection rates. Although most of the CFR variation across German states resulted from differences in the population age distribution, differences in the age structure of detected infection rates contributed substantially to this variation.

CONCLUSIONS
Differences in German CFRs depended mainly on the age structure of the population and the confirmed infection rates. Age-specific fatality played a noteworthy role only in CFR changes over time.



中文翻译：

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德国的 COVID-19 死亡率：第一波和第二波期间德国联邦州之间和内部病死率变化的人口统计学决定因素（作者：Saskia Morwinsky、Natalie Nitsche、Enrique Acosta）

背景
德国在第一​​波大流行中经历了西欧最低的 COVID-19 病死率 (CFR) 之一，并在 2020 年春季和夏季进一步下降。 然而，德国的 CFR 在第二波期间显着增加，成为西欧最高的之一。此外，德国联邦各州的 CFR 差异很大。这种 CFR 时间趋势和状态差异的驱动因素仍不清楚。

目标
我们旨在确定以下因素对德国各州之间和各州内部 CFR 差异的贡献：（1）人口年龄结构，（2）确诊感染率的年龄结构，以及（3）特定年龄死亡率。

方法
我们使用来自 COVerAGE-DB 的记录 COVID-19 病例和死亡的数据，应用 Kitagawa 和 Horiuchi 提出的人口统计分解方法。

结果
德国 2020 年春季和秋季之间的病死率下降是由于确诊感染率向年轻化和年龄别死亡率下降所致。随之而来的病死率增加主要是由于确诊感染率的年龄构成向老年转变。尽管德国各州的大多数病死率差异是由于人口年龄分布的差异造成的，但检测到的感染率的年龄结构差异对这种差异有很大贡献。

结论
德国病死率的差异主要取决于人口的年龄结构和确诊的感染率。特定年龄的死亡率仅在 CFR 随时间的变化中发挥了值得注意的作用。