Identifying the first infected case (patient zero) is key in tracing the origin of a virus; however, doing so is extremely challenging. Patient zero for coronavirus disease 2019 (COVID-19) is likely to be permanently unknown. Here, we propose a new viral transmission route by focusing on the environmental media containing viruses of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) or RaTG3-related bat-borne coronavirus (Bat-CoV), which we term the “environmental quasi-host.” We reason that the environmental quasi-host is likely to be a key node in helping recognize the origin of SARS-CoV-2; thus, SARS-CoV-2 might be transmitted along the route of natural host–environmental media–human. Reflecting upon viral outbreaks in the history of humanity, we realize that many epidemic events are caused by direct contact between humans and environmental media containing infectious viruses. Indeed, contacts between humans and environmental quasi-hosts are greatly increasing as the space of human activity incrementally overlaps with animals’ living spaces, due to the rapid development and population growth of human society. Moreover, viruses can survive for a long time in environmental media. Therefore, we propose a new potential mechanism to trace the origin of the COVID-19 outbreak.

中文翻译：

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自然宿主-环境媒介-人类：COVID-19爆发的新潜在途径


识别首个感染病例（零号病人）是追踪病毒起源的关键；然而，这样做极具挑战性。 2019 年冠状病毒病 (COVID-19) 零号病人可能永远不为人知。在这里，我们提出了一种新的病毒传播途径，重点关注含有严重急性呼吸综合征冠状病毒 2 (SARS-CoV-2) 或 RaTG3 相关蝙蝠传播冠状病毒 (Bat-CoV) 病毒的环境介质，我们将其称为“环境准宿主。”我们推断环境准宿主很可能是帮助识别SARS-CoV-2起源的关键节点；因此，SARS-CoV-2可能沿着自然宿主-环境介质-人类的途径传播。反思人类历史上的病毒爆发，我们认识到许多流行病事件是由人类与含有传染性病毒的环境介质直接接触引起的。事实上，由于人类社会的快速发展和人口增长，人类活动空间与动物生存空间逐渐重叠，人类与环境准宿主之间的接触大大增加。而且，病毒可以在环境介质中存活很长时间。因此，我们提出了一种新的潜在机制来追踪 COVID-19 爆发的起源。