While there is substantial evidence on excess mortality in the first two years of the COVID-19 pandemic, no study has conducted a cause-specific analysis of excess mortality for the whole period 2020–2022 across multiple countries. We examined cause-specific excess mortality during 2020–2022 in Denmark, Finland, Norway, and Sweden—four countries with similar demographics and welfare provisions, which implemented different pandemic response policies. To this end, we utilized nationwide register-based information on annual cause-specific deaths stratified by age and sex, and applied linear regression models to predict mortality in 2020–2022 based on the reference period 2010–2019. Excess deaths were obtained by contrasting actual and expected deaths. Additional analyses employed standardization to a common population, as well as population adjustments to account for previous deaths. Our results showed that, besides deaths due to COVID-19 (a total of 32,491 during 2020–2022), all countries experienced excess deaths due to cardiovascular diseases (in total 11,610 excess deaths), and under-mortality due to respiratory diseases other than COVID-19 (in total 9878) and dementia (in total 8721). The excess mortality due to cardiovascular diseases was particularly pronounced in Finland and Norway in 2022, and the under-mortality due to dementia was particularly pronounced in Sweden in 2021–2022. In conclusion, while COVID-19 deaths emerge as the most apparent consequence of the pandemic, our findings suggest that mortality has also been influenced by substitutions between different causes of death and over time, as well as indirect consequences of COVID-19 infection and pandemic responses—albeit to different extents in the different countries.

虽然有大量证据表明 COVID-19 大流行前两年的超额死亡率，但没有研究对多个国家/地区 2020-2022 年整个期间的超额死亡率进行特定原因分析。我们研究了丹麦、芬兰、挪威和瑞典在 2020-2022 年期间的因果超额死亡率——这四个国家具有相似的人口统计和福利规定，实施了不同的大流行应对政策。为此，我们利用了按年龄和性别分层的年度特定原因死亡的全国登记信息，并应用线性回归模型根据 2020-2022 年参考期预测 2010-2019 年的死亡率。超额死亡是通过对比实际死亡和预期死亡来获得的。其他分析对常见人群进行了标准化，并对人口进行了调整，以解释以前的死亡情况。我们的结果表明，除了 COVID-19 导致的死亡人数（2020-2022 年共有 32,491 人）外，所有国家都经历了心血管疾病导致的超额死亡（总计 11,610 例超额死亡），以及 COVID-19 以外的呼吸系统疾病导致的死亡率不足（总计 9878 例）和痴呆症（总计 8721 例）。2022 年，芬兰和挪威因心血管疾病导致的超额死亡率尤为明显，2021-2022 年瑞典因痴呆导致的死亡率不足尤为明显。总之，虽然 COVID-19 死亡是大流行最明显的后果，但我们的研究结果表明，死亡率也受到不同死因之间替代的影响，随着时间的推移，以及 COVID-19 感染和大流行应对的间接后果——尽管程度不同国家。