Revitalizing COVID-19 incidents related to cold chain food or packaging contamination
Revitalizing COVID-19 incidents related to cold chain food or packaging contamination

Revitalizing COVID-19 incidents related to cold chain food or packaging contamination

In a recent study published in the latest issue of Biomedical Journalresearchers reviewed the resurgence of coronavirus disease 2019 (COVID-19) in China related to frozen foods and packaging contaminated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).

Examination: Time course and epidemiological features of COVID-19 resurgence due to cold chain food or packaging contaminationn. Image Credit: Sorn340 Studio Images / Shutterstock

They identified one of the weak links in the SARS-CoV-2 epidemic, where the patient’s zero point often remained hidden and was difficult to detect, so that the onset of infectious diseases was only visible after a while and at that time had spread uncontrollably. Current research findings may help devise more effective COVID-19 control and intervention strategies for the future.


Following the first COVID-19 outbreak in late 2019 in Wuhan, China, several cases of COVID-19 resurgence related to frozen foods or packaging contamination have been reported as China imports frozen foods from countries where COVID-19 the epidemic is underway.

Most of these incidents reported since July 2020 are traced back to frozen shrimp imported from Ecuador. Later, in September 2020, the live SARS-CoV-2 virus was isolated from the outer packaging of imported frozen cod carried by the two stevedores that were found to be SARS-CoV-2 positive during a routine nucleic acid amplification test (NAAT) test of staff in Qingdao Port, China. According to the authors, this event is the first known case where live SARS-CoV-2 was discovered on refrigerated food in the world, confirming that it can survive on refrigerated food packaging and spread through cross-border transportation.

SARS-CoV-2 may not be responsible for the surface contamination of the material itself. Instead, the closed and very humid environment favors food packaging and processing facilities and transport material-to-human SARS-CoV-2 proliferation. To date, epidemiological features of such COVID-19 outbreaks and the risk of this route of transmission are still unclear.

In this study, researchers conducted a literature search on the official website of the Centers for Disease Control of China and local authorities to identify COVID-19 resurgence events related to cold chain foods or packaging contamination. In addition, they collected relevant epidemiological events and laboratory evidence in support of their work.

Occurrences of COVID-19 resurgence in China

On August 6, 2020, in Yingkou, Liaoning Province, China, three packaged food samples were SARS-CoV-2 positive, while all 43 employees and 306 employees of the company tested SARS-CoV-2 negative in NAAT and antibody tests. This finding led the researchers to one of the most exciting results in this literature review, which SARS-CoV-2 does not transmit via eating or purchasing cold chain foods. Thus, it is clear that only port staff, particularly stevedores, were at high risk of contracting SARS-CoV-2 as they came into direct contact with virus-contaminated materials and needed COVID-19 vaccination on priority.

Further, this finding led to the understanding that it succeeded Transfer of covid-19 for humans occurs only through the surface of the material when – i) a human (host) comes in direct contact with the SARS-CoV-2 contaminated material surface, including food packaging, and ii) the human carrier releases the virus to the surface.

Interestingly, SARS-CoV-2 remains viable (living) and stable on material surfaces, such as cardboard and plastic, for days, especially under refrigerated (4 ° C) and frozen (-10 to -80 ° C) conditions; but when it finds another human body through direct contact, it spreads rapidly via human-to-human transmission.

Deposits of COVID-19 resume in other countries

A fairly popular COVID-19 flare-up incident occurred in Auckland, New Zealand in August 2020. After 102 consecutive days with zero local cases of COVID-19 in Auckland, authorities reported four laboratory-confirmed COVID-19 cases in an Auckland household with no overseas travel history . In particular, one of the SARS-CoV-2-positive individuals in this household worked with a refrigeration chain company.

Within two days, three more employees tested SARS-CoV-2 positive, and seven family members of these cold chain workers also tested positive. In October 2020, there were 179 unknown cases with a C.12 line of SARS-CoV-2, designated as the eruption of the Auckland August Cluster.

Similarly, similar outbreaks have occurred in several other countries, including Australia, Japan, Germany and the United States, among workers at food processing plants.

In addition, there have been several cruise ship outbreaks of norovirus in the United States between July and October 2019. The current food supply review traced this infection to imported frozen raspberries from China, which then had to be recalled. Workplace conditions, such as prolonged close contact with colleagues, shared workplace and transportation, and collective housing, also increase the risk of SARS-CoV-2 infection.

According to data released by the Centers for Disease Control and Prevention (CDC), USA, between March 1st and May 31stst, 2020, there were 28,364 reported cases and 132 deaths among workers in 382 meat and poultry processing plants in several U.S. states. Often, these workplaces were overcrowded and very humid, overall conducive to human-to-human, human-to-material, and material-to-human transmissions.


To conclude, the study highlights the importance of survey materials and the whole area where imported products arrive, as frequent human tests alone are not sufficient. In addition, study data suggest that regular sampling and proper disinfection of imported products are effective ways to detect SARS-CoV-2 and prevent its spread on material surfaces.

In 2021, the Joint Prevention and Control Mechanism of the People’s Republic of China issued a series of technical guidelines for the prevention of COVID-19 transmission related to cold chain foods and the controlled occurrence of several outbreaks at the community level with the potential to become an epidemic.

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