Contamination and Transmission of SARS-CoV-2 Variants in Cold-Chain Food and Food Packaging.

The emergence of coronavirus disease 2019 (COVID-19) has posed a significant threat to global health and well-being. Vaccination serves as a vital strategy in preventing and mitigating the severity of clinical symptoms. However, due to natural selection, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has evolved, resulting in various mutations (1). Currently, the World Health Organization (WHO) has identified five variants of concern, including Alpha, Beta, Gamma, Delta, and Omicron (2). Of these, only Omicron remains in circulation and has already produced nearly one thousand sub-lineages or subvariants. These mutating variants demonstrate increased infectivity and vaccine breakthrough rates, as well as more pronounced antibody escape rates (3). COVID-19 is primarily a respiratory illness, with its main transmission routes being direct contact and the spread of droplets or aerosols (4). The Food and Agriculture Organization of the United Nations (FAO) has reported that the likelihood of SARS-CoV-2 transmission via food or food packaging is low, as the virus cannot multiply on such surfaces. In addition, upon exposure to environmental factors, viral particles degrade and become less infectious (5). Despite this, emerging epidemiological evidence suggests that imported cold-chain foods and their packaging may contribute to outbreak occurrences. According to the literature, there have been seven reported outbreaks in China associated with exposure to cold-chain food and food packaging contaminated with SARS-CoV-2. For instance, viral strain analysis revealed that the virus isolated from the outer packaging of imported cod was linked to the SARSCoV-2 infections found among dock workers during the 2020 Qingdao outbreak (6). Moreover, several COVID-19 outbreaks have occurred in meat processing facilities overseas, with a diagnosis rate of 18.2% among workers in some states of the United States (7). Individuals working in cold, humid, and crowded environments are at an increased risk for both contracting and transmitting the virus. Cold-chain food and packaging may become contaminated through two primary means: 1) viral shedding from hands coming into contact with food and packaging surfaces, and 2) expelled respiratory particles generated from talking, coughing, sneezing, and singing (8). In the investigation of the COVID-19 outbreak in Qingdao, live SARS-CoV-2 strains were successfully isolated and cultured from imported frozen seafood packaging (9). This finding suggests that SARS-CoV-2 can survive at low temperatures for several weeks, thereby enabling its spread across borders. Consumers may then transfer infectious particles from contaminated food surfaces and packaging to their eyes, noses, and mouths (10). Even during periods of strict control measures, the potential spread of SARS-CoV-2 through frozen food items and packaging, particularly imported frozen food and packaging, warrants close attention.