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By Laura Stec

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About this blog: I've been attracted to food for good and bad reasons for many years. From eating disorder to east coast culinary school, food has been my passion, profession & nemesis. I've been a sugar addict, a 17-year vegetarian, a food and en...  (More)

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Food Safety and Coronavirus: A Comprehensive Guide

Uploaded: Mar 21, 2020

This is the best information I have read about how the virus interacts with food. Thanks to author and Wursthall San Mateo chef J. Kenji López-Alt, for an extensive piece published in
Serious Eats on March 20, 2020.

If we hear any updates, we'll let you know.

BIG TAKE AWAY: Respiratory viruses reproduce along the respiratory tract—a different pathway than the digestive tract food follows when you swallow it.

Article starts here:

SARS-CoV-2: What we know
SARS-CoV-2 is the coronavirus that is causing the current outbreak of COVID-19, the name of the disease associated with it (not to be confused with SARS-CoV-1, the coronavirus that caused the original 2002 SARS outbreak). It's important to remember that while SARS-CoV-2 bears close similarities to other coronaviruses (such as SARS-CoV-1 or MERS), it is a novel virus, and new information is emerging minute by minute.

Consequently, there's a lot we don't know. That said, there's also a lot that we do know with a good deal of confidence.

How does COVID-19 spread?
Coronavirus is a respiratory virus, which means that it's spread primarily through the respiratory system. According to the Center for Disease Control (the CDC), the main transmission route is through person-to-person droplet infection—that is, the inhalation of aerosolized saliva or mucus carrying a viral load. (Viral load is the amount of virus particles in a given volume of liquid—higher viral loads equate with stronger chances of infection.) This is similar to previous coronaviruses, such as SARS-CoV-1 or MERS. Additionally, people are most contagious when they are symptomatic; coughing and sneezing spreads the virus around.

Aside from inhalation, are there other ways coronavirus can spread?
The German Federal Institute for Risk Assesment (BfR) reports that it is also possible—but unlikely—that the virus could be spread through "smear" infection. In these cases, a healthy person would touch a contaminated surface with their hands—say, a can of soup, a touchscreen ATM, or a subway turnstile—then transfer the virus to their eyes or nose. There have been no known cases of this method of transfer, and it is thought to be far less likely than droplet infection. Washing your hands before touching your face further reduces this likelihood, as coronavirus cannot be absorbed through your skin.

Currently, the CDC reports that there have been no known cases of fecal-oral transmission of COVID-19. In such a case, viral load in the stool of a carrier would make its way into the mouth of a healthy person. Some possible oral-fecal transmission routes would be from poor hygiene during food preparation, but after exposure, the virus would also have to be able to infect its host somewhere along the digestive tract.

A recent, non peer-reviewed* Chinese study of 73 possible COVID-19 patients published in Gastroenterology reports that the viral RNA was detectable and viable in over 50% of patients with COVID-19. During the original SARS coronavirus epidemic, the CDC suggests that "fecal/oral transmission may have occurred in some settings." Harvard Magazine cites a particular outbreak at a Hong Kong apartment complex where 329 residents were infected with SARS, with a vertical pattern of spread. It's theorized that faulty plumbing could have facilitated the fecal-oral or fecal-respiratory spread of the virus.

Currently, the CDC reports no fecal-oral transmission of COVID-19, but the possibility is not ruled out.

*As all research on COVID-19 is new, very little, if any, has been through rigorous peer-review processes thus far.

How long does the virus stay on contaminated surfaces?
A study funded by the NIAID and published in the New England Journal of Medicine found that SARS-CoV-2 can be detected in aerosols (airborne droplets smaller than five micrometers) for up to three hours, on copper for up to four hours, on cardboard for up to 24 hours, and on stainless steel or plastic for up to three days. (Follow the link for more comprehensive graphs of viral load decay.)

This means that if a delivery person or package handler infected with the virus coughs or sneezes on packages or envelopes, the virus can stay on those packages for up to a day, while plastic take-out containers or steel work surfaces can hold the virus for three days. The viral load on any surface will decrease logarithmically with time; that is, the number of virus particles decreases rapidly at the start, then slowly approaches zero over time.

According to Chapman, there is currently no consensus on the minimum viral load necessary for infection. Some scientists put the number as low as a single virion—given ideal conditions (read: if your food has a lone virion on it, you’d have to intensely smear the food on your hands then purposely rub them in your eyes and up your nose).

Should I avoid touching things other people have touched?
Avoiding all potentially contaminated surfaces is unrealistic. Still, there are two easy ways you can minimize the risk: Transfer food and other goods—whether delivered to your door or bought at the store—to clean containers when it makes sense to, and wash your hands thoroughly after checking the mail or venturing out of your home.

Coronavirus is fragile and easily destroyed by hand soap, disinfectant wipes, and cleaning sprays (we’ll get to more specific details on this).

How long does the virus last on food?
The data for how long the virus can remain viable on food is limited, but in general, viral loads remain more stable on non-porous surfaces like metal and plastic, and break down faster on organic surfaces like cardboard.

Can I get COVID-19 from touching or eating contaminated food?
There is currently no evidence that COVID-19 has spread through food or food packaging.

According to multiple health and safety organizations worldwide, including the CDC, the USDA, and the European Food safety Authority, there is currently no evidence that COVID-19 has spread through food or food packaging. Previous coronavirus epidemics likewise showed no evidence of having been spread through food or packaging.

Are we sure food isn’t a vector of COVID-19 transmission?
No, we don't know for sure. However, there is strong evidence to suggest that food is not a vector. The epidemiology of food-borne pathogens is well studied, with government data going back to 1938. The spread pattern of COVID-19 does not fit models of foodborne outbreaks, which are defined as two or more people getting sick from the same contaminated food or drink.

For instance, Singapore has tracked its COVID-19 patients and submitted them to extensive interviews by teams from the Ministry of Health to try to determine patterns of spread. It's been found that most cases are linked to clusters of people, including hotel guests attending conferences, church groups, and shoppers, while none are linked to contaminated food or drink.

The fact that every person eats multiple times a day and thus far no link has been found between eating and viral clusters is strong evidence that no such link exists.

I’m still not convinced. How could food not be a vector?
Let’s say a food worker coughs while preparing my food, how could I not pick up the virus from eating it? This confused me as well, which is why I specifically inquired about it. According to Chapman, the risk is minimal. Even if a worker sneezes directly into a bowl of raw salad greens before packing it in a take-out container for you to take home, as gross as it is, it's unlikely to get you sick.

This 2018 overview of both experimental and observational study of respiratory viruses from the scientific journal Current Opion in Virology (COVIRO) explains that respiratory viruses reproduce along the respiratory tract—a different pathway than the digestive tract food follows when you swallow it. And while you might say that you just inhaled that salad, more likely you ate it with a fork and swallowed it

What about eating with your hands?
So if ingesting the virus isn't a concern, what about this scenario: a worker coughs on a cutting board then assembles a hamburger directly on that board before placing it in a take-out container. You then come home and eat that burger with your bare hands, then pick your nose, or do something else that deposits the virus along your respiratory tract. In this situation, the viral load has been diluted several times. First when it was transferred from the board to the burger bun. Next, more viral load was shed when the bun was placed in the takeout container. It is diluted again when you pick up the burger before interacting with your face in inadvisable ways. While he didn't rule out the possibility of picking up the disease this way, Chapman described it as "a moonshot, even before you touch your face."

Using clean silverware when possible and washing your hands after eating and before touching your face further minimizes that risk.

Are there any special risks associated with food?
None that have been recognized. Food handlers are specifically trained in proper safety and hygiene procedures. Federal and state-level regulations mandate everything: the location of handwashing sinks, the type of soap used in them, the frequency of work-surface sanitization, the temperature of the dishwasher, the temperature to which various foods must be cooked, the rate at which they must be chilled, the cleaning and storage process for raw product, et cetera. Any restaurant or market that handles, packages, or serves food should be—and usually is—following all of these guidelines. The penalties for noncompliance vary by jurisdiction, but are typically severe, ranging from posted notices for minor violations to outright shut-downs to multiple minor violations or major violations. (Here are California’s code and enforcement guidelines, for reference.)

The point is: Eating food is not any riskier than any number of other activities you perform on a daily basis in which you come into contact with items other people have handled. Indeed, the hygiene standards in place at food service operations make that risk even smaller.

Am I more likely to get COVID-19 from take-out, delivery, or cooking at home?
The main risk factor is proximity to other people, so inasmuch as you have a higher chance of coming in contact with other people outside your own home, picking up food is a higher risk than having it delivered or cooking it yourself.

That said, there are other risks associated with cooking at home, particularly in shopping at supermarkets and handling potentially contaminated food packaging. The cook at your local restaurant most likely follows stricter hygiene and safety protocols than the supermarket worker stocking the shelves. A good rule of thumb is to treat anything that comes into your home from outside, whether food, mail, or other people, as potentially contaminated and act accordingly. Wash your hands after bringing it home, transfer to clean containers and/or sanitize packaging when possible, and wash your hands before, during, and after cooking. (And stop picking your nose.)

Does Chinese food pose a greater risk than other food? What about imported food and goods?
There’s no indication of additional risk associated with imported foods or other products. Viral load decreases on all products with time—whether that's a plastic toy or a bunch of bananas. The increased transportation time for imported goods means that it’s far more likely to be contaminated by the person unloading the shipping container or stocking the grocery store shelf than anyone at its point of origin.

While it is true that COVID-19 originated in China, all indications show that the transmission to other countries has been person-to-person, which is why efforts by authorities ranging from state and local governments to the WHO are focused on limiting person-to-person contact, not the movement of goods.

If I’m still concerned, does reheating food before eating it destroy the virus?
Yes. As with any bacteria or virus, safe cooking is a function of temperature and time. The hotter the temperature, the less time you'll need to reduce viral or bacterial load to a safe level. With salmonella, for instance, 165°F (75°C) is hot enough to make a 5-log reduction in bacterial load in under a second (that is, only one out of every 100,000 bacteriums will survive that temperature and time). At 145°F (63°C), the same reduction in pathogens would take around 10 minutes. (Bear in mind this is the temperature of the food, not the oven.

Temperatures and times for coronavirus are not yet fully researched, but scientists suggest a temperature of 149°F (65°C) for at least 3 minutes is sufficient. Experts assume that the virus will respond like other pathogens and that hotter temperatures will require shorter times, but we currently do not have experimental data to prove it.

When reheating or cooking solid foods, such as a chicken breast, a steak, or a loaf of bread, it is very unlikely that any viral or bacterial load will have penetrated past the surface unless the food has been pierced or cut, so heating just the exterior is sufficient (for safety, if not for palatability).

How do I sterilize my food?
• Heat liquids like soups, stews, and sauces to a brief simmer, making sure to stir frequently so that it heats evenly throughout.
• Microwave vegetables, pasta, thick purées like mashed potatoes, and meat until piping hot—hot enough that you’d worry about burning your mouth if you took a bite. For most microwaves, that means about 90 seconds per serving on high heat (but microwave power can vary).
• Sauté loose bite-sized items like short pasta shapes, loose vegetables, or stir-fries until they maintain a steady sizzle as you stir them around the pan. A minute or two in a preheated skillet is sufficient for a couple of servings.
• To reheat cutlets, casseroles, or bread in the oven, preheat the oven to 400°F (205°C), place the food on an oven-safe tray with shallow sides (high sides can block hot air from circulating), and heat until the surface of the food is too hot to touch for more than an instant.
• If you own a sous-vide circulator, follow the appropriate sous vide recipe guide in our archives. Treat whatever food you are reheating as if it were starting from raw. (See the next section for more information on the safety of slowly reheating food.)
• Chopped-and-formed foods like meatloaf, meatballs, dumplings, falafel, etc. should be thoroughly heated to the center, following the time and temperature guidelines stated above (heat to an internal temperature of at least 149°F/65°C, and hold it there for at least 3 minutes).

If you want to be extra-careful, use a digital thermometer to check the temperature of your food inside and out before serving or eating.

Does "the danger zone" apply to SARS-CoV-2?
You may be familiar with the concept of "the danger zone," the temperature range of 41°F to 135°F in which bacteria thrive. Proper food handling dictates that foods spend no longer than four hours total between those temperature ranges before consumption. When reheating food, this includes the original cook time, the cooling time, and the reheating time (pay extra attention to this when reheating foods sous vide). The good news is that viruses require a host cell to replicate, which means that the coronavirus will not multiply on your food, even within the danger zone. Indeed, just as it does on other surfaces, the viral load on your food will decrease with time.

That said, you should still continue to follow good food safety procedures and mind that danger zone—all the normal bugs are around, even during the coronavirus pandemic.

Are we going to run out of food?
Because limiting your time out of home can slow the spread of the virus, it’s a good idea to make fewer, larger trips to the supermarket. But how much food do you really need? Initial panic and hoarding behavior has caused short-term shortages at supermarkets and grocery stores across the country. But there’s good news: the FDA reports that there are currently no long-term issues with food supplies. In all likelihood, you’re still going to be able to buy eggs, dairy, dried and canned goods, paper products, fresh meat and produce, and even soap next week and next month. There’s no need to buy a three month supply of canned soup or years’ worth of toilet paper.

That said, we have yet to see the long-term effects of COVID-19 on farms (especially as it relates to seasonal workers whose dense living arrangements are ripe grounds for coronavirus spread), or the trucking and shipping industry. Food wholesalers will also have to alter supply chains to accommodate higher sales in supermarkets and online retailers, and lower sales in restaurants. Many restaurants have shuttered for an indeterminate period, an others, like my own restaurant, Wursthall, have shifted to limited, take-out-and-and-delivery-only menu formats. (Beyond food safety, this brings with it a host of other economic implications.)

Time will tell, but the reality is that those of us who were food-secure before this outbreak will likely remain so. It’s those of us who were most vulnerable before the outbreak who are most likely to suffer now. I urge you to look into local organizations that assist families and individuals in need to see how you can help. Time and money are equally valuable resources these days.

Here are a few ways you can keep yourself safe at the supermarket:

• Go at off-peak hours to avoid crowds. Bonus: Most supermarkets restock their shelves with deliveries late at night. Hit them up at this time or early in the morning and you’ll be rewarded with wide open, freshly-stocked aisles.
• Keep your distance in line. I've seen people lining up right next to each other for the pharmacy and the supermarket checkout. Don't do that! Wait in line at least 6 feet away from the person in front of you, and gently request that anyone behind you follow the same rule, for everyone's safety.
• Overfill your prescriptions if possible. Talk to your Doctor about ensuring you have enough of your prescription medications to last for at least several weeks to avoid extra trips to the pharmacy.
• Using the self-checkout lane reduces your contact with other people, but it also increases interaction with secondary potential infection points, like the touchscreen display and the bar code scanner. On balance, I’d recommend avoiding person-to-person contact over surface contact and stick with the self-checkout. If you do go with a cashier, bag your own groceries rather than having them handled by another person any longer than necessary.
• Wash your hands when you get home and if possible, use a hand sanitizer after leaving the store and before touching the door to your vehicle or home.
• Don't hoard. This is not the zombie apocalypse. Get what you’ll need for a few weeks at most.
• Use touchless pay systems. Your phone probably already has a touchless pay system you can link to your bank account. If you can't go touchless, use a credit card and avoid cash when possible.

Is it okay to buy produce from open bins?
So long as you are following proper food preparation procedures at home—clean, separate, cook, and chill—and following the basic hygiene guides explained here and elsewhere, the risk from getting COVID-19 through produce that other people have touched is minimal.

Remember: not a single positive case has been linked to food.

Read more of the article here

Source: Food Safety and Coronavirus: A Comprehensive Guide
Serious Eats
by J. Kenji López-Alt

What is it worth to you?


Posted by CrescentParkAnon., a resident of Crescent Park,
on Mar 21, 2020 at 2:29 pm

Wow!, very interesting and amazingly thorough, thanks.

Posted by CrescentParkAnon., a resident of Crescent Park,
on Mar 22, 2020 at 10:07 am

Found this on You-Tube that suggests that with increased vitamin D levels upper respiratory infections decreased.
Vitamin D & the Upper Respiratory Tract: Web Link

Perhaps COVID-19 defense can be enhanced with vitamin D supplementation?

Posted by Sam Abdullah, a resident of Crescent Park,
on Mar 22, 2020 at 12:41 pm

While news of a novel and deadly virus spreading across the globe may be terrifying, it's important to recognize that there's another, more familiar virus in this country to be concerned about: it's the flu. According to the CDC, there have already been up to 51 million cases of the flu this season, leading to hundreds of thousands of hospital admissions and up to 55,000 deaths.
Getting a flu shot is a great first step if you're worrying about avoiding illness. Other measures to protect yourself from the flu (such as staying away from others who are sick and taking care to not infect others if you're sick) are basic strategies that can also help you avoid the new coronavirus.

Posted by Plagiarism?, a resident of Adobe-Meadow,
on Mar 22, 2020 at 4:22 pm

Is it okay to verbatim repost someone else's content here?

Posted by Laura Stec, a resident of Portola Valley,
on Mar 22, 2020 at 4:34 pm

I asked the author, and have credited him through various means.

This information is critical.

Posted by Mark Weiss, a resident of Downtown North,
on Mar 23, 2020 at 1:09 pm

Mark Weiss is a registered user.

Hi, Laura.
I am still wondering about using the Mitchell Park kitchen to feed people during a concert in the adjacent El Palo Alto Room Ball room. So far the closest we've gotten is using the kitchen as a green room when the other meeting spaces are booked by someone else day of show.
Which reminds me: I taped an Alice Waters special on PBS Friday, and she was friends with Les Blank the filmmaker whose work colors or informs or "exhales" (inspires) my taste in music -- see "Werner Herzog Eats His Shoe".

I gained 20 pounds during the time that Ramen Nagi has opened on my street, Bryant downtown. I was their first customer -- in fact waited thru the line twice on their opening day -- and overall have had maybe 20 bowls there. My question: do you think being slightly overweight helps ward off viruses or the opposite I am putting that much more stress on my heart and lungs?

Posted by Laura Stec, a resident of Portola Valley: other,
on Mar 23, 2020 at 7:16 pm

Mark Weiss, have you tried food trucks at the shows?

Interesting you gained weight on broth. Look more to alcohol, sweets, soda and processed foods. Extra weight doesn't seem to help many medical conditions, it's more stress on the body of course, but ask your doctor, or dietician.

Thanks for using your name.

Posted by John Zussman, a resident of Portola Valley,
on Mar 25, 2020 at 12:37 pm

Well-researched and very timely. Thanks for posting, Laura.

Posted by Laura Stec, a Almanac Online blogger,
on Mar 26, 2020 at 12:43 pm

Laura Stec is a registered user.

This video by a Michigan MD shows tips about how to handle / sanitize packaging of food. I am using it for now, we need to know more.

Posted by Violet, a resident of Old Palo Alto,
on Mar 27, 2020 at 6:48 pm

Covid19 is not just a respiratory disease, it also presents in some as a gastrointestinal disease, and appears to attack other organs like the heart in some people. The experts keep saying “don't touch your face" for a reason - because you can get it by picking up the virus on your hands and then it getting into your eyes, nose, or mouth. Those are two important things that I wish were expressed in this interesting article.

Posted by Laura Stec, a resident of Portola Valley,
on Mar 27, 2020 at 7:09 pm

Violet, Gosh that is so true, why aren't we talking about it?

I've got to think about that for a moment - thank you

Posted by resident, a resident of Midtown,
on Mar 29, 2020 at 9:45 am

I have read reports from other doctors debunking that Michigan doctor scrubs video which takes food cleaning way beyond what most Americans currently do or are even willing to do. Here is a much simpler approach that a Harvard professor published in the Washington Post: Web Link

Posted by Laura Stec, a resident of Portola Valley: other,
on Mar 29, 2020 at 10:03 am

Thank you resident. More info is good info as we learn how best to handle food during this crisis.

Posted by CrescentParkAnon., a resident of Crescent Park,
on Mar 29, 2020 at 10:17 am

It's not good that this information-filled article has slipped off the front page, so to speak, of the blog posts. Can't something be done to keep this front and center?

Posted by Laura Stec, a resident of Portola Valley,
on Mar 29, 2020 at 10:27 am

CPA, the posts circulate on a 7 day cycle. I could post it again I guess?

Posted by CrescentParkAnon., a resident of Crescent Park,
on Mar 29, 2020 at 3:06 pm

I don't know the policies of Palo Alto Online, other than to pick on my poor posts for editing and deleting ;-) , but that sounds like a reasonable idea to me. Or you could post something in the Town Square and then any new comment would pop it to the top, right? Thanks for this information by the way, very useful.

Posted by Ed, a resident of Nixon School,
on Jun 13, 2020 at 10:16 am

I would like to know if the person making my Hamburger is talking and his/her spray from there mouth goes onto my Bun does the virus live on that bun .. and now i eat this... is this a possible way to spread the virus ??

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