Long Distance Transmission of SARS-CoV-2 from Contaminated Cold Chain Products to Humans — Qingdao City, Shandong Province, China, September 2020

Abstract

What is already known about this topic?Though coronavirus disease 2019 (COVID-19) has largely been controlled in China, several outbreaks of COVID-19 have occurred from importation of cases or of suspected virus-contaminated products. Though several outbreaks have been traced to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) isolated on the outer packaging of cold chain products, live virus has not been obtained. What is added by this report?In September 2020, two dock workers were detected as having asymptomatic SARS-CoV-2 infection using throat swabs during routine screening in Qingdao, China. Epidemiological information showed that the two dock workers were infected after contact with contaminated outer packaging, which was confirmed by genomic sequencing. Compared to the Wuhan reference strain, the sequences from the dock workers and the package materials differed by 12-14 nucleotides. Furthermore, infectious virus from the cold chain products was isolated by cell culture, and typical SARS-CoV-2 particles were observed under electron microscopy. What are the implications for public health practice?The international community should pay close attention to SARS-CoV-2 transmission mode through cold chain, build international cooperative efforts in response, share relevant data, and call on all countries to take effective prevention and control measures to prevent virus contamination in cold-chain food production, marine fishing and processing, transportation, and other operations.

SARS‐CoV‐2 cold‐chain transmission: Characteristics, risks, and strategies

“…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 cold‐chain products each outbreak, and were subjected to SARS‐CoV‐2 specific RT‐PCR testing.…”

Strengthening Community Defenses to Prevent and Control the Spread of COVID-19 in China

“…With the increase of e-commerce, more people buy foods that need cold chain transportation from overseas online shopping platforms. The epidemic situation abroad is serious, and it is difficult to avoid carrying the virus in the outer package of express delivery or even cold chain food ( 5 ). People working in the cold chain or receiving deliveries are at risk of infection.…”

“…Currently, China's epidemic prevention focuses on people from overseas and domestic high-risk areas, as well as imports of cold-chain items. While vaccines remain highly effective at preventing severe disease and death (2-3), they do not fully prevent transmission (4). After the community finds a positive infected person, it is important to determine the close contacts and subclose contacts as soon as possible and transfer them as soon as possible.…”

Possible processes and origin-tracing methods of “human-to-item” contamination and “item-to-human” infection with SARS-CoV-2

“…Since the “item-to-human” phenomenon of SARS-CoV-2 has been confirmed by scientific methods [2] , the possibility exists that the same batch of articles can simultaneously cause multiple transmission chains in the same area. This process can be illustrated by a group of people sharing a pizza ( Figure 1 ), with each person randomly eating a part of the pizza with a certain ingredient (tomato/green pepper/bacon).…”

“…The outbreak of COVID-19 in mainland China was declared controlled after April 2020. Since then, the origins of all local outbreaks were imported cases of COVID-19 infection or imported articles contaminated with SARS-CoV-2 [1] , [2] , [3] . The volume of import and export trade in China is enormous, and the entry of SARS-CoV-2-contaminated articles into China is inevitable.…”