No link between food and spread of coronavirus
South African Dr Lucia Anelich, adjunct professor in the Centre for Applied Food Security and Biotechnology at the Central University of Technology, specialist in microbiological food safety and former president of the South African Association of Food Science and Technology (SAAFoST) said the risk of contracting the virus through food was “negligible”.
“There is no evidence that this virus is distributed via food or food packaging.
“So far, the main routes of transmission are person to person via close contact, such as shaking hands and hugging, droplets from coughing and sneezing and contaminated surfaces.”
Anelich said a study recently published in the New England Journal of Medicine titled “Aerosol and Surface Stability of SARS-CoV-2 as Compared with SARS-CoV-1” revealed that the virus could only contaminate surfaces for limited time periods.
The study was undertaken by Neeltje van Doremalen and Trenton Bushmaker of the National Institute of Allergy and Infectious Diseases in Hamilton, Montana, Dylan H Morris of Princeton University, New Jersey, and other researchers.
The study evaluated the stability of SARS-CoV-2 (Covid-19) and SARS-CoV-1 in aerosols and on various surfaces - plastic, stainless steel, copper and cardboard, and estimated their decay rates. The study found that the SARS-CoV-2 virus could survive for:
3h in aerosol (duration of experiment)
Up to 4h on copper
Up to 24h on cardboard
Up to 3 days (72 hours) on plastic and stainless steel
Anelich noted that survival rates of the virus depend on heat and humidity in the environment.
“At higher temperatures, it is likely to survive for less time; at lower temperatures such as refrigeration, it is likely to survive for longer periods.”
Anelich said freezing was not regarded as a “kill step” for most viruses in food.
Food-borne viruses, for example, survive freezing so that once the food is defrosted, these viruses would be able to infect a person ingesting the contaminated food if not cooked or reheated adequately before consumption.
Even though the SARS-CoV-2 virus was not a food-borne virus, it was just as likely to survive freezing as other coronaviruses do.
She said the main difference between bacteria and viruses was that bacteria grew in food.
“A virus cannot grow outside its host, but can remain viable for different periods of time depending on many factors, including the temperature and humidity of the environment.”
Anelich said that because there was still much that we do not know about the virus, it was important to take precautionary measures, one of which was to practise proper hand hygiene when handling any food packaging to ensure that the risk of transmission via this route remained negligible.
She said her personal routine when returning from the shops included washing her hands with soap and water for 20 seconds before and after unpacking her shopping.
“Soap destroys the fatty (lipid) layer around the virus, which then inactivates it.
“If people wish to take it a step further they can disinfect the outside of the bags with household bleach diluted to a 0.1% solution.
“This equates to 1 cup of normal household bleach (at 3.5% sodium hypochlorite) to 34 cups of water.
“I rotate my re-usable shopping bags, so that I have washed bags daily. I wash them in hot water and normal household washing powder.
“People can disinfect kitchen surfaces as well if they wish.
“If disinfectant wipes are used, make sure they are able to kill viruses and not only bacteria; use them only once and throw them away immediately in a lined bin.
“Practising proper hand hygiene and maintaining a social distance of 2m are two of the most critical steps in the fight against transmission of this virus between people.”
She added that while no data was currently available on temperatures at which SARS-CoV-2 was killed, data on SARS-CoV-1 and other human coronaviruses showed that they were killed at 60°C after 30 minutes in a protein-rich environment.
She said roasting meat or chicken usually led to core temperatures of at least 71 to 72°C, which should be more than enough to kill the virus, if present.
Dr Jeff Farber, professor in the Department of Food Science at the University of Guelph in Ontario, and director of the Canadian Research Institute for Food Safety, said scientists were currently unaware of any reports linking Covid-19 illness related to food or food packaging or touching other surfaces in supermarkets.
“We should always be practising good hygienic habits in relation to food safety practices, so before you start preparing food and before you sit down to eat, remember to wash your hands thoroughly with lukewarm water and soap for 20 seconds.
“This is no different to what we have always emphasised, even in non-pandemic situations.”
He said that to prevent infection, many grocery stores were offering hand sanitisers at the entrance and to sanitise grocery trolleys.
“You should ensure that this is available.
“Before you go the supermarket, prudent advice is to make a list, know what you want and move quickly and efficiently through the store, picking out the items on your list.
“Practise appropriate social distancing, trying your best to keep 1.8m away from other shoppers.
“Use the hand sanitiser available (or bring your own), when exiting the store.”
He advised people to use disinfect wipes to disinfect any surfaces used to put the food on before packing it in afridge or cupboard, and to again wash your hands before eating.
“Coronaviruses in general can fairly easily be killed off by the normal temperatures that we use in cooking. So, normal baking, cooking and frying should inactivate the virus.”