key: cord-0903025-33kq8oj5 authors: Chen, Cao; Feng, Yenan; Chen, Zhixiao; Xia, Ying; Zhao, Xiang; Wang, Ji; Nie, Kai; Niu, Peihua; Han, Jun; Xu, Wenbo title: SARS‐CoV‐2 cold‐chain transmission: Characteristics, risks, and strategies date: 2022-04-08 journal: J Med Virol DOI: 10.1002/jmv.27750 sha: dcae9a161202e93827f25a2e551193229b269e87 doc_id: 903025 cord_uid: 33kq8oj5 Low temperature and certain humidity are conducive to severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) for long‐time survival and long‐distance spread during logistics and trades. Contaminated cold‐chain or frozen products and outer packaging act as the carrier of SARS‐CoV‐2, that infects the high‐risk population who works in the ports, cold storage or seafood market. Since the coronavirus disease 2019 (COVID‐19) pandemic worldwide, multiple localized outbreaks caused by SARS‐CoV‐2 contaminated imported cold‐chain products have been reported in China, which brought challenges to COVID‐19 prevention and control. Here, we review the evidences of SARS‐CoV‐2 cold‐chain transmission from six confirmed cold‐chain related COVID‐19 outbreaks in China, especially in terms of SARS‐CoV‐2 whole‐genome sequencing and virus isolation. In addition, we summarize the characteristics and mode of SARS‐CoV‐2 cold‐chain transmission from both six COVID‐19 outbreaks in China and the outbreaks suspected cold‐chain transmission in other countries. Finally, we analyze the underlying risks of SARS‐CoV‐2 cold‐chain transmission and propose the preventive countermeasures. and hidden transmission route, may introduce SARS-CoV-2 into the low prevalence countries and regions. [3] [4] [5] The survival time of SARS-CoV-2 is related to humidity, temperature and other conditions. Low temperature and certain humidity are conducive to the survival and infectivity of the virus, 3, 6 indicating that cold-chain fomites may be more suitable for SARS-CoV-2 long-time survival and long-distance spread during international trades. Since June 2020, SARS-CoV-2 RNA had been detected in imported cold-chain products in most provinces of China. 7 outbreaks have been confirmed in China. These outbreaks had ruled out the introduction of imported COVID-19 cases according to the field epidemiological investigation, thereby cold-chain products in contact with the initial case were the primary targets for further screening. According to the investigations of detailed field epidemiology, all six outbreaks were associated with SARS-CoV-2 contaminated imported cold-chain products exposure. [9] [10] [11] [12] [13] [14] The related cold-chain products importers came from the Europe or North America (Table 1) . To trace the source of SARS-CoV-2 that caused the outbreak, samples were taken from the surface of the initial or index cases associated coldchain products each outbreak, and were subjected to SARS-CoV-2 specific RT-PCR testing. Although the positive rates of SARS-CoV-2 RNA varied greatly (0.8%-40.7%), SARS-CoV-2 RNA was detected from the surface samples of cold-chain products in all six outbreaks. SARS-CoV-2 RNA was found on the surface of frozen food in two outbreaks and that in the outer packaging of frozen products in other four outbreaks. The key evidences of six COVID-19 outbreaks were marked in Figure 1 , including the presence of complete field epidemiological evidence, the relevance of SARS-CoV-2 full-length genomes of coldchain products to the initial cases, as well as the successful isolation of alive SARS-CoV-2 from initial case associated cold-chain products. Among that, the relevance of SARS-CoV-2 full-length genomes divided into three degrees: (I) Complete identical virus means that the genome of SARS-CoV-2 from the cold-chain products same as the one from initial case; (II) Former generation virus means that the genome of SARS-CoV-2 from the cold-chain products lacked one nucleotide mutation than the one from the initial case; (III) Highly homologous virus means that the genome of SARS-CoV-2 from the cold-chain products shared key nucleotide mutations with the one from the initial case. 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The authors declare no conflicts of interests. All data generated or analyzed during this study were kept by National Institute for Viral Diseases Control and Prevention, China CDC. Please contact author for data requests.