Amid a flurry of concern over reports that frozen chicken wings imported to China from Brazil had tested positive for the coronavirus, experts said on Thursday that the likelihood of catching the virus from food — especially frozen, packaged food — is exceedingly low.
“This means somebody probably handled those chicken wings who might have had the virus,” said Angela Rasmussen, a virologist at Columbia University. “But it doesn’t mean, ‘Oh my god, nobody buy any chicken wings because they’re contaminated.’”
Guidelines from the Centers for Disease Control and Prevention maintain that “there is no evidence to suggest that handling food or consuming food is associated with Covid-19.” The main route the virus is known to take from person to person is through spray from sneezing, coughing, speaking or even breathing.
“I make no connection between this and any fear that this is the cause of any long-distance transmission events,” said C. Brandon Ogbunu, a disease ecologist at Yale University. When the virus crosses international boundaries, it’s almost certainly chauffeured by people, rather than the commercial products they ship.
The chicken wings were screened on Wednesday in Shenzhen’s Longgang district, where officials have been testing imports for the presence of coronavirus genetic material, or RNA. Several samples taken from the outer packaging of frozen seafood, some of which had been shipped in from Ecuador, recently tested positive for virus RNA in China’s Anhui, Shaanxi and Shandong provinces as well.
Laboratory procedures that search for RNA also form the basis of most of the coronavirus tests performed in people. But RNA is only a proxy for the presence of the virus, which can leave behind bits of its genetic material even after it has been destroyed, Dr. Ogbunu said. “This is just detecting the signature that the virus has been there at some point,” he said.
To prove that a dangerous, viable virus persists on food or packaging, researchers would need to isolate the microbe and show in a lab that it can still replicate. These experiments are logistically challenging and require specially trained personnel, and aren’t a part of the typical testing pipeline.
After samples taken from the surface of the meat came up positive, officials performed similar tests on several people whom they suspected had come into contact with the product. They also tested a slew of other packaged goods. All samples analyzed so far have been negative for coronavirus RNA, according to a statement released by the Shenzhen Epidemic Prevention and Control Headquarters Office.
But the same statement cautioned consumers about imported frozen products, and early reports of the news sparked alarm on social media. In New Zealand, where a new outbreak has set off another lockdown, officials are tentatively exploring the possibility that the virus might have reentered the country via frozen products imported from abroad.
Both Dr. Ogbunu and Dr. Rasmussen said that an extraordinarily unusual series of events would need to occur for the virus to be transmitted via a frozen meat product. Depending on where the virus originated, it would need to endure a potentially cross-continental journey in a frozen state — likely melting and refreezing at least once along the way — then find its way onto someone’s bare hands, en route to the nose or mouth.
Even more unlikely is the scenario that a virus could linger on food after being heated, survive being swallowed into the ultra-acidic human digestive tract, then set up shop in the airway.
“The risks of that happening are incredibly small,” Dr. Rasmussen said.
Some viruses might be able to weather such an onerous pilgrimage. But the coronavirus probably isn’t one of them because it’s a so-called enveloped virus, shrouded in a fragile outer shell that’s vulnerable to all sorts of environmental disturbances, including extreme changes in temperature.
Viruses are often frozen in laboratories that maintain stocks of pathogens for experiments. But virologists must monitor that process carefully to avoid destroying the vulnerable bugs.
The Coronavirus Outbreak ›
Frequently Asked Questions
Updated August 12, 2020
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Can I travel within the United States?
- Many states have travel restrictions, and lots of them are taking active measures to enforce those restrictions, like issuing fines or asking visitors to quarantine for 14 days. Here’s an ever-updating list of statewide restrictions. In general, travel does increase your chance of getting and spreading the virus, as you are bound to encounter more people than if you remained at your house in your own “pod.” “Staying home is the best way to protect yourself and others from Covid-19,” the C.D.C. says. If you do travel, though, take precautions. If you can, drive. If you have to fly, be careful about picking your airline. But know that airlines are taking real steps to keep planes clean and limit your risk.
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I have antibodies. Am I now immune?
- As of right now, that seems likely, for at least several months. There have been frightening accounts of people suffering what seems to be a second bout of Covid-19. But experts say these patients may have a drawn-out course of infection, with the virus taking a slow toll weeks to months after initial exposure. People infected with the coronavirus typically produce immune molecules called antibodies, which are protective proteins made in response to an infection. These antibodies may last in the body only two to three months, which may seem worrisome, but that’s perfectly normal after an acute infection subsides, said Dr. Michael Mina, an immunologist at Harvard University. It may be possible to get the coronavirus again, but it’s highly unlikely that it would be possible in a short window of time from initial infection or make people sicker the second time.
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I’m a small-business owner. Can I get relief?
- The stimulus bills enacted in March offer help for the millions of American small businesses. Those eligible for aid are businesses and nonprofit organizations with fewer than 500 workers, including sole proprietorships, independent contractors and freelancers. Some larger companies in some industries are also eligible. The help being offered, which is being managed by the Small Business Administration, includes the Paycheck Protection Program and the Economic Injury Disaster Loan program. But lots of folks have not yet seen payouts. Even those who have received help are confused: The rules are draconian, and some are stuck sitting on money they don’t know how to use. Many small-business owners are getting less than they expected or not hearing anything at all.
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What are my rights if I am worried about going back to work?
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What is school going to look like in September?
- It is unlikely that many schools will return to a normal schedule this fall, requiring the grind of online learning, makeshift child care and stunted workdays to continue. California’s two largest public school districts — Los Angeles and San Diego — said on July 13, that instruction will be remote-only in the fall, citing concerns that surging coronavirus infections in their areas pose too dire a risk for students and teachers. Together, the two districts enroll some 825,000 students. They are the largest in the country so far to abandon plans for even a partial physical return to classrooms when they reopen in August. For other districts, the solution won’t be an all-or-nothing approach. Many systems, including the nation’s largest, New York City, are devising hybrid plans that involve spending some days in classrooms and other days online. There’s no national policy on this yet, so check with your municipal school system regularly to see what is happening in your community.
“The act of freezing and unfreezing is a kind of violent thermodynamic process,” Dr. Ogbunu said. “A virus, for all its toughness and robustness, is a very delicate instrument of infection.”
The C.D.C. has noted that “it is possible” that the coronavirus can spread through contaminated surfaces, including food or food packaging. But that’s not known to be among the main ways the virus gets around.
If you don’t want get infected, avoiding direct contact with other people is probably a better use of your time, Dr. Ogbunu said.
“Yes, we should continue to wash our hands and be mindful of surfaces where a lot of individuals are,” he said. “But it’s close proximity to others that can really facilitate transmission.”