A new study exploring the potential that COVID-19 can linger on food, including frozen seafood, draws connections between recent outbreaks of the virus in China, Vietnam and New Zealand.
The study, “Seeding of outbreaks of COVID-19 by contaminated fresh and frozen food,” was published in the journal BioRxiv which circulates preliminary findings that have not been scrutinized by peer review.
“An explanation is required for the re-emergence of COVID-19 outbreaks in regions with apparent local eradication. Recent outbreaks have emerged in Vietnam, New Zealand, and parts of China where there had been no cases for some months. Importation of contaminated food and food packaging is a feasible source for such outbreaks and a source of clusters within existing outbreaks,” according to the study’s abstract.
In June, traces of the coronavirus were discovered on fish chopping boards in Beijing’s Xinfadi seafood market, which had become the epicenter of a new cluster of COVID-19 infections. More recently, samples taken from one of the internal walls of a container transporting Ecuadorian shrimp to China tested positive for COVID-19, as well as on the outer surface of five boxes from these companies.
In New Zealand, some of the infections in a recent outbreak were traced back to the Americold cold storage facility in Auckland, the country’s most populous urban area. And Vietnam, a country that had won praise for its aggressive measures in containing the virus, suffered scores of infections and ten deaths in August.
The study’s researchers, from Singapore and Ireland, said their lab work shows the novel coronavirus can endure the time and temperatures associated with transportation and storage conditions for international food trade, according to a Fox News report.
Transmission of COVID-19 on food – deemed a “non-traditional” theory of transmission – was the focus of the study. It found that at 21–23 degrees Celsius, no viable SARS-CoV-2 remained after four hours on copper surfaces, 24 hours on cardboard and after three days on stainless steel and plastic surfaces.
However, studying the survival of SARS-CoV-2 on refrigerated and frozen meat and salmon over three weeks, the current study found that “there was no decline in infectious virus after 21 days at 4 degrees Celsius (standard refrigeration) and minus-20 degrees Celsius (standard freezing).”
“Our laboratory work has shown that SARS-CoV-2 can survive the time and temperatures associated with transportation and storage conditions associated with international food trade.”
The study counters a World Health Organization statement from August 13 that reported food or food packaging had not been linked to the transmission of COVID-19. However, the study’s authors posit that COVID-19 can potentially jump from contaminated seafood to a worker processing the product, who then can become a vector of the virus.
“Our findings, coupled with the reports from China of SARS-CoV-2 being detected on imported frozen chicken and frozen shrimp packaging material, should alert food safety competent authorities and the food industry of a ‘new normal’ environment where this virus is posing a non-traditional food safety risk,” the authors wrote.