- The Chinese CDC has concluded that the recent Qingdao outbreak started after two people were infected from handling contaminated frozen food packages.
- The conclusions seem to be in line with what is known about the virus so far. SARS-CoV-2 can survive on surfaces for hours, it lives longer in dark, cold places, and fomite transmission is possible.
- However, the CDC failed to provide irrefutable proof that the two people were not infected elsewhere and then contaminated the food packages themselves. Also, it’s unclear from the available reports whether the virus on those packages was infectious.
The Chinese CDC released a new warning on Saturday saying that frozen food packaging contaminated by active coronavirus could cause infection. The latest finding concerning food packaging and the novel coronavirus in a few months. China battled a COVID-19 outbreak in Beijing a few weeks ago, months after the capital had no confirmed cases. In the process, Chinese scientists disclosed they’d discovered traces of coronavirus on a table in a market used for cutting salmon. This drove the entire salmon supply chain in a temporary frenzy, with the crisis spanning thousands of miles to China’s trade partners.
The WHO reminded people at the time that food isn’t infectious, although fomite transmission was a theoretical possibility. For months, we’ve known that the virus can survive for hours to days on certain materials; that’s why authorities advise people to wash their hands often and clean commonly used surfaces. A more recent study showed that the virus could survive for 28 days at room temperature in total darkness.
Soon after the Beijing outbreak, New Zealand officials revealed they were also looking at frozen food packaging as a potential coronavirus source for a new outbreak. Later, researchers showed the virus could survive at low temperatures. China CDC’s new findings follow a new outbreak in the city of Qingdao.
Reports a few days ago said China was going to test the entire Qingdao population after a few cases were discovered in the city. The plan was to test nine million people in five days to determine the outbreak’s scope and identify the source.
The China CDC now says it has isolated living coronavirus on the outer packaging of frozen cod, as it was tracing the virus in Qingdao. If the findings are accurate, it indicates China would have the ability to perform a similar investigation into the pandemic’s actual source.
Nearly 10 months after the coronavirus health crisis began in Wuhan, China is yet to explain how it all started. The country said time and again that the virus had not escaped from a lab. Researchers have already proved that the virus evolved naturally in animals before jumping to humans. A few months ago, China said the first outbreak did not originate in the Wuhan market, which was the first version of the coronavirus origin story. But it never offered an additional explanation. A joint China-WHO investigation should look into the matter at some point in the future.
China CDC’s findings would be a world first, per Reuters — that the virus can travel over long distances via frozen goods. The agency tested nearly 3 million samples from 24 regions by September 15th, including 670,000 from cold-chain food or food packaging, 1.24 million from staff, and 1.07 million from the environment. Only 22 samples from the cold-chain food or food packaging tested positive for the virus. It’s unclear whether all of them contained live viruses or just genetic material.
It started with two Qingdao dock workers who were initially diagnosed as asymptomatic in September, but they brought the virus to a hospital where it spread to 12 other people. It’s unclear whether the patients ever became symptomatic, and whether they were in presymptomatic phase at the time. It’s widely accepted that asymptomatic people do not spread the virus as much as symptomatic ones, but many people are infections in the presymptomatic phase. China has played fast and loose with coronavirus figures in its reports. The country did not count asymptomatic patients when releasing COVID-19 data, but it did quarantine them.
China’s CDC findings do make some sense. Research has shown that the virus can survive on surfaces for days, that it fares better in a darker, colder, environment, and that it’s still infectious.
But the disease control authority has not provided solid proof that the two workers got the illness from food packaging and not from a different source. Jin Dong-Yan, a virology professor at the University of Hong Kong, told Reuters the two could have contaminated the food packaging themselves. Jin also pointed out that samples taken from surfaces would test positive even if the virus is no longer contagious. As a reminder, the same thing happened with samples from a cruise ship several months ago. The US CDC found traces of the novel coronavirus 17 days after the Diamond Princess was evacuated. Experts explained that the virus was probably not infectious at the time.
The Chinese agency said it detected living coronavirus on the packages. The agency could have performed experiments that show the virus can infect cells.
While more research is surely required to determine what the risk of fomites transmission from frozen food packaging is, China CDC’s conclusions are still useful. The agency advises workers who handle, process and sell frozen food to avoid direct skin contact with products that could be contaminated. Staff should refrain from touching their face (nose, mouth, eyes) before taking off work garments that could also carry the virus. They should wash their hands before touching the face and should be tested regularly. The agency also said there was no instance of a consumer being infected after contact with frozen food and that the risk continues to remain low.
