Chinese authorities have been investigating imported meat, packaging and containers as a possible source of Covid-19 since June, after repeatedly discovering traces of the pathogen in packaging and food.

Coronavirus in frozen salmon can be contagious for more than a week, according to researchers in China who studied the role of frozen imported fish as a potential source of infection.

Researchers at the Rural University of Southern China and the Guangdong Academy of Agricultural Sciences in Guangzhou County have found that SARS-CoV-2, the virus that causes Covid-19 was found in salmon samples and could survive for up to 8 days at 4 degrees Celsius temperature.

This is approximately the temperature at which the fish are transported. The research was evaluated by the academic community this week.

Chinese authorities have been investigating imported meat, packaging and containers as a possible source of Covid-19 since June, after repeatedly discovering traces of the pathogen in packaging and food. Six of the more than 500,000 samples tested were positive for the coronavirus, China’s customs agency said in a report on Tuesday.

“SARS-CoV-2-contaminated fish from one country can be easily transported to another country within one week, thus serving as one of the sources for international transmission,” the researchers said, noting that fish are kept at a temperature of 0 to 4 degrees Celsius during shipping.

The government is trying to prevent contamination by strengthening cooperation with meat exporting countries. Since Monday, China had suspended imports from 56 companies in 19 countries as there have been cases of contamination of employees.

The first outbreak of the pandemic disease was initially linked to the Hunan seafood market in the central Chinese city of Wuhan in late 2019, while a outbreak in June was linked to the Xinfanti seafood market in Beijing.