Is the Risk of Transmission of Coronavirus From Groceries Significant?

Check out this answer from Consensus:

The risk of transmission of coronavirus from groceries is multifaceted, involving direct contact, aerosol transmission, and potential foodborne routes. While the risk from groceries is not negligible, it can be mitigated through proper ventilation, social distancing, and hygiene practices. Further research is needed to fully understand the long-term survival and infectivity of the virus on food surfaces and to develop comprehensive risk mitigation strategies.

The COVID-19 pandemic has raised numerous concerns about the various ways the virus can be transmitted. One area of particular interest is the potential risk of contracting the virus through groceries. This article aims to explore the evidence and assess whether the risk of transmission of coronavirus from groceries is significant.

Transmission Risks in Grocery Stores

Grocery stores are essential services that have remained open throughout the pandemic, making them a focal point for potential virus transmission. A study conducted in a grocery retail store in Massachusetts, USA, found that 20% of the workers tested positive for SARS-CoV-2, with a significant portion being asymptomatic. Employees with direct customer exposure were five times more likely to test positive for the virus, highlighting the risk associated with close contact in grocery environments1.

Aerosol Transmission in Markets

Aerosol transmission is another potential route for the spread of COVID-19 in grocery settings. A case study of the South China Seafood Market used quantitative microbial risk assessment (QMRA) to evaluate the risk of aerosol transmission. The study found that the median risk of a customer acquiring SARS-CoV-2 infection via aerosol after one hour of exposure was relatively low but could increase significantly with multiple infected individuals present. The risk decreased rapidly outside the market due to air dilution2.

Foodborne Transmission

The possibility of foodborne transmission of SARS-CoV-2 has also been investigated. While there is no conclusive evidence of foodborne transmission, studies have shown that the virus can persist on frozen and refrigerated foods for extended periods. For instance, SARS-CoV-2 remained stable under refrigerated conditions (4°C) and freezing conditions (-10 to -80°C) for 14-21 days on various food surfaces. This suggests that contaminated cold-storage foods could pose a risk for virus transmission, especially in the context of international trade3.

Ventilation in Grocery Stores

Adequate ventilation is crucial in minimizing the risk of airborne transmission of SARS-CoV-2 in grocery stores. Research has indicated that poorly ventilated indoor spaces pose a higher risk for virus transmission. Computational fluid dynamics simulations have shown that the design of ventilation systems in grocery stores can significantly affect the risk of aerosol exposure, with some designs creating “hot spots” of reduced ventilation and increased risk4.

Is the risk of transmission of coronavirus from groceries significant?

Donald Schaffner has answered Unlikely

An expert from Rutgers University in Microbiology, Food Safety

There is no evidence currently that COVID-19 be transmitted by food. The biggest risk when it comes to COVID-19 and groceries is being around other people in the grocery store while you are shopping.

Should I keep my groceries in the garage or on the porch for 3 days?

This is patently ridiculous. Are you really going to keep your milk, your ice cream, your deli meats outside for three days? This also has very important food safety implications. This sounds like a recipe for disaster, or at the very least spoiled food.There is a tiny nugget of truth in this advice, because we know that the virus is slowly inactivated at room temperature, with a half-life of about eight hours. But this advice presumes that all groceries are contaminated, and the simply touching the groceries will make you sick, neither of which are true.

Do I really need to disinfect all of the individual boxes & baggies everything came in?

I also think that this is also advice that does not make scientific sense. If you are concerned about the outside of food packages being contaminated, I suggest that you wash your hands and or sanitize your hands before you sit down to eat any food that you might’ve taken out of those containers. And guess what, washing your hands before you eat is a best practice even when we’re not in a pandemic!

Washing fresh produce with soap? Soap should *absolutely* not be used to wash food. Soap is not designed for food. As mentioned in the linked thread, soap can cause nausea, vomiting and diarrhea if ingested. Current recommendations by scientific experts including the FDA, say to wash fresh fruits and vegetables in cold water. See my earlier answer for more details.

Are reusable bags risky?

Many people use reusable bags as a responsible choice. We do this in my family as well. It’s a best practice (even before the times of pandemic) to wash your reusable bags on a regular basis. While it is theoretically possible that a reusable bag may pick up germs, including coronavirus while in the grocery store, the biggest threat that anyone faces is someone else in the store who has COVID-19. I would suggest that you keep your grocery bags in the car, so you have them handy the next time you go shopping. If you’re concerned that your bags might have coronavirus on them you can wash them. You should also wash your hands after you have finished putting all your groceries away. This was also a good advice even before pandemic.

What I can do to reduce risk when grocery shopping?

Many grocery stores are offering hand sanitizers at the entrance, and are offering to sanitize grocery carts. Both great ideas, and customers should take advantage if available.My other advice is to make a list, and know what you want, and move quickly and efficiently through the store picking out the items on your list. Practice appropriate social distancing, trying your best to keep 6 feet away from other shoppers. If there is hand sanitizer available, I also use it when I’m exiting the store, and then I’ll use it again at home once I finished putting all my groceries away and returning my reusable shopping bags to the car.

Is the risk of transmission of coronavirus from groceries significant?

Nigel Cook has answered Unlikely

An expert from Jorvik Food and Environmental Virology in Virology

Although the virus appears to have arisen in a food market where live animals were kept, it is likely that human exposure occurred due to handling of, or proximity to, an animal host, rather than consumption of animal products. It is possible that contamination of food surfaces could occur due to handling by an infected person; however, there is no current evidence that SARS-Cov2 can be transmitted in this way. Nevertheless, to be prudent it is good practice to wash the surfaces thoroughly of any foods intended to be consumed uncooked, e.g. fruit, salad vegetables. For cooked foods, it is recommended to follow guidelines such as those provided by the UK Food Standards Agency https://www.food.gov.uk/safety-hygiene/cooking-your-food.

Is the risk of transmission of coronavirus from groceries significant?

Robson Machado has answered Unlikely

An expert from University of Maine Cooperative Extension in Food Safety, Microbiology

As other experts already said, we do not have enough evidence that the virus can be transmitted through surfaces and make people sick. Yes, some preliminary research shows that the virus can survive for hours or days on different surfaces. However, we still don’t know how easy it would be for people to get sick by surface cross-contamination. 

Understandably, some people want to be as cautious as possible. When faced with an unknown situation, we crave for any form of control over the possible outcomes. But, we should strive for a balance between being careful and paranoid. There is data that shows that a sneeze can travel 27 feet (~8 meters), but that is the upper limit. Using that as a reference for everyone is counterproductive. It is like saying that since some humans can run 100 m in less than 10 seconds, we should time our crosswalk light signs with those numbers as a reference. 

Is the risk of transmission of coronavirus from groceries significant?

Francisco Diez-Gonzalez has answered Unlikely

An expert from University of Georgia in Food Safety

From the current pandemic, there is has been no documented instances that indicate that the virus can be transmitted via food or food packaging.

Many reputable brands of packed foods and supermarkets are closely monitoring their employees to minimize the possibility that a sick worker handles the food. While handling of foods by customers during shopping cannot be controlled, there is again no evidence that supports this route of transmission.