A handful of headlines claiming “Ice cream tests positive for coronavirus in China” have been doing the rounds on social media. Fortunately, it doesn’t mean this dairy dessert has fallen sick with the infection, but it does suggest that it's possible for food supply chains to become contaminated with the virus. Rest assured though, the risk of catching COVID-19 from any food remains extremely low.
Authorities in northern China say they've identified three samples of ice cream that were contaminated with SARS-CoV-2, the virus that causes COVID-19, according to Xinhua Chinese state media.
The ice cream was produced by Tianjin Daqiaodao Food Co. Ltd in Tianjin, a major port city in northeastern China. During their investigation to find the source of the contamination, they found that the ice cream was using ingredients from aboard, such as milk powder imported from New Zealand and whey powder imported from Ukraine. All 1,662 employees at the food company were placed under quarantine and tested for COVID-19 with 962 people still awaiting their results and 700 testing negative.
Not much information is available about the case, but it appears that the ice cream or some of its ingredients became contaminated by a person infected with COVID-19 at some point along the supply chain. It’s possible the virus may have entered up in the food simply an infected person coughing, sneezing, or even breathing near the food. Since ice cream is not heated or cooked during its processing, the virus was not inactivated. It is unlikely that chilling or freezing would be effective in inactivating COVID-19.
A study, published in the journal Environmental Chemistry Letters in October 2020, looked into the question of whether COVID-19 can be transmitted from food, concluding that foodborne transmission of COVID-19 might be possible and has largely gone ignored throughout the pandemic.
The study found that the virus could potentially survive in a frozen environment for several weeks, noting "the continuous low-temperature environment kept through the storage and transport of refrigerated and frozen foods can dramatically prolong the survival of SARS-CoV-2.” It also documents at least nine cases where SARS-CoV-2 had been detected on frozen foods, including packaging materials and storage environments, by health authorities across the world. However, they did not investigate how many people have actually become infected with COVID-19 via foodborne transmission.
Back in June 2020, there were reports from China that a COVID-19 outbreak in Beijing stemmed from contaminated meat or fish after a salmon cutting board at Xinfadi market tested positive for SARS-CoV-2. Genome sequencing of the virus identified it as a variant common in Europe, suggesting the virus had been carried by a frozen salmon from Europe to China. However, authorities were unable to confirm this theory and some suggested the outbreak was simply caused by an ill market worker.
In sum, food can become contaminated with SARS-CoV-2 and harbor the virus for some time. It’s also possible that infections can occur in anyone who ingests contaminated food that has not been cooked. While no studies have looked to quantify the risk of catching COVID-19 from food, the risk appears to be low in the grand scheme of things.