There have been a number of enquiries regarding whether Food Consulting Services can test directly for the virus that causes COVID-19 (Severe Acute Respiratory Syndrome Coronavirus 2, abbreviated to SARS-CoV-2) in a client’s facility. The short answer is No; the full answer is But it doesn’t matter. In this article, we argue that testing for general hygiene and cleanliness is far more effective in suitability and cost.

The “gold standard” method to detect SARS-CoV-2 is called reverse-transcription (DNA) polymerase chain reaction (abbreviated to RT-PCR). This is the method widely used to determine if a patient is infected or not. In essence, the method can find tiny traces of viral genetic material (RNA) in a sample. It is first converted to DNA using an enzyme called reverse-transcriptase and the DNA is then amplified by PCR, which is a well-established method. At the end of the process, many copies of the DNA have been made (in the case of a positive result) and these can then be relatively easily detected.

To quote other experts on the subject of environmental testing for COVID-19:

There are two potential reasons for testing surfaces in a food facility for COVID-19; to indirectly detect an infected individual, or to confirm the efficacy of cleaning procedures. If the goal is to detect the presence of an infected individual, environmental testing is a poor substitute for other measures that could be used.

Whether testing surfaces or human beings, the assay for the novel coronavirus is a test for the presence of short stretches of DNA with the same sequence as the RNA genetic material of the virus. This RNA must be isolated using a swab, and transported in a nuclease-free solution, before being transcribed, using an enzyme, into DNA copies.

Given the prevalence of RNAse enzymes in the environment, the results of an environmental swab are likely to be far more prone to false negatives than those taken directly from a human respiratory tract. The results from a surface swab would also only be available in 24 to 48 hours, severely limiting the value of this information. Professor Pieter Gouws, Centre for Food Safety at Stellenbosch University

False results in environmental testing for COVID-19

To elaborate further, a False Negative is when the virus is actually present but the test fails to detect it. The opposite is a False Positive when there is no virus present but the test says there is. Besides the chance of a False Negative mentioned above, there is also the risk of what I call a “functional” or effective False Positive. What we mean is that detecting traces of the viral genetic material (RNA) does not necessarily mean there are any active/infectious virions present. So the RT-PCR result may come back positive and create an unnecessary response (even panic) when there was actually no risk to anyone’s health.

The active virus particles (virions) can only be detected using other, culture-based, techniques that are both more costly and time-consuming than the standard genetic test. So the accuracy of the “gold standard” genetic test, perfect in a clinical setting (because the patient’s own signs and symptoms will prove the virus is indeed active), is highly questionable in a food facility. Recall also that the risk of transmission from foods or surfaces is considered very low.

There is no evidence that food is a significant mode of transmission for the SARS-Cov-2. Dr Lucia Anelich, Anelich Consulting

Environmental Testing for COVID-19

Thankfully, the virus particles have a fatty (lipid) envelope (membrane) around them. This makes them highly susceptible to the same kinds of chemicals that are widely used to kill other germs when sanitising and disinfecting surfaces and equipment. Such chemicals include the detergents called Quaternary Ammonium Compounds (QACs), chlorine (actually hypochlorite) and ethyl alcohol (ethanol).

This means that one can draw a reasonable scientific inference: if we apply one of the above sanitisers, and can prove that it has worked by showing that very few (or no) bacteria have been left behind afterwards, it is highly likely that any SARS-CoV-2 viruses have been inactivated too (assuming they were there in the first place). Thus it is important at this time to question whether environmental testing for COVID-19 is a suitable approach for detecting the virus in your food manufacturing, service or retail premises.

At the start of the spread of COVID-19, other laboratories and experts identified suitable testing methods for the SARS-CoV-2 virus. Based on scientific evidence, their understanding of the virus and the relevant applications in the food industry, they chose not to add this testing option to our testing catalogue.

FCS has adopted the same approach. Instead of using the expensive and possibly inaccurate (in this context) RT-PCR test (kits of which are currently in short supply for medical use, adding another dimension as to whether it is even ethical to “waste” them on this application), we advocate using the basic, highly reliable standard plate count that detects general microbes on a surface.

As a food microbiology laboratory and hygiene audit service provider, we are not able to test for the virus directly however, we are currently offering additional testing of surface and hand swabs, which are tested for SPC (standard plate count) bacteria. These tests serve as an indicator of general hygiene and sanitation. This allows us to provide feedback on how effective your hand washing/sanitising and increased cleaning regimes are.

Remember the main means of spreading SARS-CoV-2, like any respiratory virus, is through person-to-person contact, secondly, through small viral-laden droplets and aerosols and only in a much more limited way through touching surfaces. Nevertheless improved sanitation of such “high-volume hand-contact” surfaces is recommended, and here our standard plate count will provide objective, independent scientific verification of sanitation (as always).

Don’t forget to institute physical distancing in conjunction with face-masks, and reinforce existing food safety hygiene and sanitation measures. This will be effective for preventing the spread of the virus. Detecting the presence of an infected individual is most effectivity achieved by directly testing staff, and this should, therefore, take precedence over environmental sampling for COVID-19.

A final word from the USA’s Food and Drug Administration:

Currently, there is no evidence of food or food packaging being associated with the transmission of COVID-19. Therefore, we do not believe there is a need to conduct environmental testing in food settings for the virus that causes COVID-19 for the purpose of food safety. Cleaning and sanitising the surfaces is a better use of resources than testing to see if the virus is present. Facilities are required to use personnel practices that protect against contamination of food, food contact surfaces and packaging, and to maintain clean and sanitised facilities and food contact surfaces.

Although it is possible that an infected worker may have touched surfaces in your facility, FDA-regulated food manufacturers are required to follow Current Good Manufacturing Practices (CGMPs). Maintaining CGMPs in the facility should minimise the potential for surface contamination and eliminate contamination when it occurs. With the detection of the coronavirus in asymptomatic people and studies showing survival of coronavirus on surfaces for short periods of time, as an extra precaution food facilities may want to consider a more frequent cleaning and sanitation schedule for high human-contact surfaces.

Additional Reading :

The role of surface swabbing during COVID-19

Food safety and coronavirus disease 2019 covid-19 

Learn More About COVID-19

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