Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) rapidly spread around the world during 2020, but the precise time in which the virus began to spread locally is difficult to trace for most countries. Here, we estimate the probable onset date of the community spread of SARS-CoV-2 for heavily affected countries from Western Europe and the Americas on the basis of the cumulative number of deaths reported during the early stage of the epidemic. Our results support that SARS-CoV-2 probably started to spread locally in all western countries analysed between mid-January and mid-February 2020, thus long before community transmission was officially recognised and control measures were implemented.

中文翻译：

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追踪 SARS-CoV-2 在西方国家社区传播的起始日期。

严重急性呼吸综合征冠状病毒2（SARS-CoV-2）在2020年在世界各地迅速传播，但对于大多数国家来说，很难追踪该病毒开始在当地传播的确切时间。在这里，我们根据疫情早期报告的累计死亡人数，估计了西欧和美洲受影响严重的国家中 SARS-CoV-2 社区传播的可能开始日期。我们的结果表明，SARS-CoV-2 很可能在 2020 年 1 月中旬至 2 月中旬之间开始在所有西方国家进行本地传播，远早于社区传播得到正式认可并实施控制措施。