Coronavirus Testing: New Environmental Testing Options

May 18, 2020

A few weeks ago I wrote a blog about coronavirus testing in the indoor environment. At that time we did not have laboratory testing for the virus itself, so we had to use other types of testing as surrogate indicators of the biological cleanliness of the surface such as ATP swabs or efficacy testing. Over the past month, commercial labs have made analyses for the SARS-CoV-2 virus available commercially. 

The tests that are available at this time are genetic based analysis called RT-PCR (reverse transcription polymerase chain reaction). In layman’s terms, this test looks for sections of genetic material that are unique to the novel coronavirus. The whole genome of the SARS-CoV-2 virus was sequenced in early 2020, and molecular biologists were able to find areas of the RNA (the virus’s genetic code) that were unique to the novel virus, they were then able to create clinical tests to identify that genetic code in samples. With genetic-based testing, there are levels of specificity. Some genes are present in almost all living things, some genes are unique to an individual organism, and some genes are at every level in between.

Laboratories offer a range of services at different price points. A cheaper method is to analyze a sample for ALL coronaviruses. These work by looking for an area of the genome unique to coronaviruses, but not an area of the genome that is able to differentiate between the SARS-CoV-2 virus and other coronaviruses. This can be a cheaper screening tool that can give reliable negative results and presumptive positive results. In the event that a sample is presumptively positive, the lab can then reanalyze that sample for the SARS-CoV-2 specific markers to determine if the novel coronavirus is in fact present. 

Depending on the laboratory, different regions of the RNA are targeted, with some laboratories even looking for multiple gene markers in their analysis. The CDC has listed 3 sequences suitable for diagnostic testing, N1, N2, and RNA polymerase genes. Results for the virus testing is reported as “present/absent” since we do not have interpretation guidelines to tell us what an “acceptable” level of the virus on a surface is, quantification is not important for our analysis.

One of the great things about genetic-based testing is that samples can be processed from a number of different collection techniques. Commercial laboratories advertise coronavirus testing from swabs, water samples, and even air samples. The most practical way for most situations would be surface swabs of high touch areas, but special cases may call for different types of sample collection. Another benefit is RT-PCR testing can be done within a few hours, with many laboratories offering the same day or next day results if needed. Currently, there isn’t a way to get immediate results on-site for direct measurement of the coronavirus causing COVID-19.

This analysis is very similar to the clinical testing that is done on specimens collected from humans, but this process does not check for the same genes that the clinical testing checks for. Don’t go sampling yourself and sending it into the laboratory for analysis!

It is important to note, that RT-PCR detects the presence of genetic material from the coronavirus; it does not determine if the virus is viable or if it is in a high enough quantity to cause COVID-19.  For example, someone can cough onto their computer screen and later spray that screen with a registered disinfectant. If the disinfectant does its job, it will kill the virus, but unless the screen is physically cleaned, the virus’ genetic information will still be present. If Indoor Science was hired to swab that computer screen, we could get a positive result even though the virus itself was killed by the disinfectant and can’t cause disease.  This emphasizes the importance of cleaning as a step before doing disinfection.

As we slowly start to return to “normal”, many companies are looking to hire cleaning companies to disinfect their workplaces, and clearance testing is a great way to document that the process has been performed to an acceptable level. If you have questions about coronavirus testing, cleaning protocols, training, feel free to contact us!