When It Comes to COVID-19 Disinfectants: Use With Care

As the fight against coronavirus disease 2019 (COVID-19) continues, the consumer market for gadgets to keep you from touching doorknobs and elevator buttons, and gizmos to disinfect your phone, your packages, your groceries, glasses, shoes, and the air you breathe—just to name a few—is mind-boggling. Similarly, lots of new and old technologies are being marketed to the healthcare sector, promising cleaning and disinfection on all kinds of surfaces contaminated with SARS-CoV-2.

Contact with surfaces contaminated with the virus is of great concern even though the primary mode of transmission is through close, prolonged contact (defined as <6 feet for >/=15 minutes¹) with respiratory droplets and aerosols. There is possible risk of transmission, albeit low, from inadvertently touching a deposit of these respiratory particles on a surface, and then touching one’s face or eyes. Recently, an article published in The Lancet² spoke about real life SARS-CoV-2 transmission versus laboratory-simulated situations stating “the chance of transmission through inanimate surfaces is very small, and only in instances where an infected person coughs or sneezes on the surface, and someone else touches that surface soon after the cough or sneeze (within 1–2 hours).” Knowing that contaminated surfaces may place patients and healthcare workers at risk, let’s look at some of the technology being marketed for use in disinfection of COVID-19 contaminated surfaces.

Ultraviolet Germicidal Irradiation (UVGI) is a type of ultraviolet (UV) light that is composed of 3 types of light—UVA, UVB, and UVC.UVC is the most effective of all germicidal light. It was first used in the early 19th century³ as a method to disinfect air. It was during this time that the spread of airborne infections by droplet nuclei was discovered, and also the bactericidal effects of sunlight (UV) to prevent that spread. Despite early successes in applying UVGI, its use fell out of favor. However, in the 1980s, an increase in infections from tuberculosis (TB) led to renewed interest in UVGI. It was found to be safe and very effective in disinfecting the air, preventing transmission of a variety of airborne infections in addition to TB.

Sharon Ward-Fore, MS, MT(ASCP), CIC

When it comes to disinfecting the air, there are 3 primary methods of applying UVC systems against infectious agents in the air: upper-air, coil irradiation, and airstream disinfection. Upper-air systems are typically installed in room spaces, such as above patient beds, in waiting rooms, corridors and break areas, etc., where they kill airborne microorganisms that inherently circulate into the path of the UVC light.

Coil irradiation and airstream disinfection systems are installed within air handling units or duct runs within HVAC systems, downstream of cooling coils, to keep coils clean and to provide supplemental kill ratios in airstreams and on filter surfaces. Reduction of potential pathogens in the air can help prevent resettling onto surfaces, helping to contribute to a reduction in microorganism transmissions.

In healthcare, we hear a lot about UVC being used to disinfect surfaces more so than air or water. It relies on a short wavelength of light to break down microorganisms by naturally damaging their DNA and RNA, rendering them unable to replicate. Since viruses are not considered microorganisms, UVC does not actually “kill” viruses. Instead, it inactivates the virus and prevents any illnesses it might spread.

Promising Method

UVC has been shown to be effective in reducing pathogenic microorganisms present on frequently touched surfaces and is already being used in some hospital settings for disinfecting rooms, surfaces, and equipment. Interestingly, the US Centers for Disease Control and Prevention (CDC)⁴ lists UVC as one of the most promising methods of disinfecting air-filtering face masks, such as the N95, for reuse when there is a shortage of personal protective equipment (PPE).UVC devices are an effective means of reducing concentrations of airborne and surface microorganisms that can lead to healthcare-associated infections (HAIs).

Until very recently, UVC wavelength devices for disinfection of surfaces had not yet been proven effective against COVID-19. There were only data to support effectiveness against other coronaviruses with fairly similar RNA structures to the virus that causes COVID-19. However, on May 21, 2020, Xenex recently tested its LightStrike™ robot specifically on SARS-CoV-2 in a biomedical lab in Texas, and found that, in 2 minutes, it was able to achieve a reduction of the virus greater than 99.99% within about a 3-foot radius.⁵

So, the effectiveness of UVC for reduction of microorganisms including bacteria, viruses, and fungi has been proven time and again. But using UVC radiation to disinfect is not simple and requires lots of protocols to use safely. The radiation must be contained, often in a device of some kind, be it a light box, robot, or tower. When UVC light is used to disinfect a room, people must be cleared from the room before the device is turned on because it can be harmful to eyes and skin. Sometimes the robots need to be repositioned to eliminate “shadowing,” which blocks the UV light from touching the surface intended for disinfection. Installing UVC lights to irradiate a room or determining the placement of mobile devices is also a complicated process and must be appropriately validated to work effectively. Some systems are very costly. Lastly, and most importantly, all surfaces need to be free of any soil or bioburden in order for the UV light to touch the surface and for disinfection to occur, therefore, it does not replace cleaning. It can be a powerful tool used as an adjunct to a thorough cleaning process.

Misters, foggers, fumigation, or electrostatic sprayingare technologies used to apply disinfectants, like hypochlorous acid and hydrogen peroxide, to entire rooms such as empty public waiting rooms, operating rooms, and patient care spaces. Misters work by using a pressure pump that operates under pressure (ex, 1000 psi) and pushes water and any other product through small orifices that atomize the substances and turn them into a mist. Foggers work almost the same way but turn the mist into fog by allowing for flash evaporation. Electrostatic sprayers work by charging liquids (ie, cleaners, sanitizers, disinfectants) as they pass through a sprayer nozzle.

This generates charged droplets that repel one another and, when applied to environmental surfaces, they stick to and even wrap around them to coat all sides. This “whole room” approach to disinfection can help eliminate some of the human error that may occur from the repetitive and tedious task of repeatedly cleaning patient care spaces as often as needed in a healthcare environment. Whole room disinfection devices also limit the use of chemicals which benefit the environment as well as the employees who are exposed to harmful cleaning products on a regular basis. Some of these devices, in addition to disinfecting surfaces, have been proven to clean the air as well.

EPA’s Role

Since disinfectants are considered pesticides, they are reviewed and regulated by the US Environmental Protection Agency (EPA). Unless the disinfectant product label specifically includes disinfection directions for fogging, fumigation, or electrostatic spraying, the EPA does not recommend using these methods to apply disinfectants because the EPA has not evaluated the product’s safety and efficacy for methods not addressed on the label. Also, a disinfectant’s safety and effectiveness may change based on how it is used. Currently, the CDC recommends cleaning contaminated surfaces with liquid disinfectant products to prevent the spread of disease. However, the EPA announced the expedited review of certain Pesticide Registration Improvement Act (PRIA) submissions for products already on List N that are effective against COVID-19 and applied for use using alternate application methods such as misters, foggers, fumigation and electrostatic spraying.⁶ One such product, Spore Defense applied through the Clorox Total 360® electrostatic sprayer, may be an effective way to eliminate SARS-CoV-2 from complex surfaces and is eligible for use against SARS-CoV-2, based on the EPA’s emerging Viral Pathogen Policy.

No doubt more and more makers of disinfectants will consider submitting an application to use these alternate methods for “whole room“ disinfection. Keep in mind all of these technologies still require cleaning of the surfaces prior to their use. They also have some time constraints for application and re-occupancy of the area. Fogging, for example, is typically carried out for a minimum of 15 to 30 minutes to enable the fog to disperse and the chemical action to occur. After fogging, an additional 45 to 60 minutes is required for the droplets to settle from the air onto the surfaces. During this “aeration” period, no one should enter the area. Also, when fogging, the equipment in the space being addressed should be limited, and the remaining equipment should be powered off and covered so that the disinfectant does not penetrate the sensitive electronic circuitry. If powering off and covering the equipment is not an option, fogging should not be considered. A final, very important consideration should also include the health and safety of staff and patients in areas where this technology is being routinely used.

Surface coating technologies range from antimicrobial agents for medical devices and surgical implants such as silver and copper to coatings that ensure surfaces are disinfected. They prevent the growth and spread of bacteria on surfaces such as medical instruments, walls, counters, door handles, and other high-touch areas. Silver ions prevent bacteria from reproducing. Copper destroys bacteria by damaging bacterial DNA and cell proteins. Copper is also effective against viral and fungal pathogens. Now there is an EPA-approved surface coating with antiviral properties effective for use against SARS-CoV-2 and proven to provide long-term, non-toxic surface protection within 2 hours of application for up to 7-90 days.⁷ The non-toxic coating “SurfaceWise2” is applied via an electrostatic spray to provide always-on protection on treated surfaces.

These long-lasting surface coatings may help provide persistent reduction in environmental contaminants, potentially improving patient outcomes. One thing to consider might be what are the long-term effects of coating, then recoating hospital equipment and surfaces? Much more to come as the surface coating race continues.

Dry heatobtained by a achieving a temperature of 100 °C, 5% relative humidity for 50 minutes was found to effectively decontaminate 3 million N95 masks, allowing for reuse by healthcare workers during shortages, based on a study by the University of Illinois. It did not alter their integrity or fit and was least likely to reduce the filtration efficiency when compared with other available decontamination methods such as moist heat, ethanol, isopropanol solution, bleach, and ultraviolet light. The study found that “...dry heat decontamination generated by an electric cooker, like rice cookers, instant pots, and ovens could be an effective and accessible decontamination method for the safe reuse of N95 respirators.”⁸ The mask should be enveloped in a towel or dishcloth to prevent it from touching the side of the pot and melting.

If an oven is being used to decontaminate the mask, it should be placed in a paper bag and no part of the mask should come in contact with the heating element to prevent a fire. We may scoff at this now, but continuing increases in COVID-19 infections leading to increased hospitalizations may again causes PPE shortages, so keep your eye on that instant pot.

Comprehensive Evaluations

During the trial and evaluation of any technology for disinfection, infection preventionists, environmental services (EVS) crew, and other stakeholders should undertake a comprehensive evaluation of the item under consideration.

For example, any new device being considered for purchase and implementation in a healthcare organization should be evaluated for its cost-effectiveness; whether the technology demonstrates a reduction in infection rates that justifies the cost associated with the purchase and maintenance of the device; whether the claims made by the manufacturer, such as spectrum of activity or dwell for disinfectants, are pertinent to your hospital and doable by your staff. Evaluators should identify the ongoing costs involved in use, education and training, staffing, and sustainability. Finally, any new technology should be evaluated for its relevance of use once the COVID-19 pandemic has passed.

Even now the need for enhanced cleaning surrounding COVID-19 is being questioned. Is it really needed and sustainable? Ask yourself a couple of questions before jumping feet first into any of these technologies. Will this technology also help with reduction of multidrug-resistant organisms or other problem organisms seen at my facility? Is my current level of cleaning and disinfection acceptable? Are there other things that could be done to improve cleaning and disinfection at my facility without adding to current practices? No matter the answer, know these technologies are available to add to your “toolbox” of best cleaning and disinfection practices when you need them but be aware of the caveats for their use.

Sharon Ward-Fore, MS, MT(ASCP), CIC, is an infection prevention consultant located in Chicago. She is also a member of Infection Control Today®’s Editorial Advisory Board.

1. CDC Centers for Disease Control and Prevention. Coronavirus Disease 2019 (COVID-19) Health Departments, Public Health Guidance for Community-Related Exposure. Current guidance based on community exposure, for people exposed to people with known or suspected COVID-19 or possible COVID-19. Updated July 31, 2020, Accessed August 30, 2020. https://www.cdc.gov/coronavirus/2019-ncov/php/public-health-recommendations.html​
2. Goldman E. Exaggerated risk of transmission of COVID-19 by fomites.Lancet Infect Dis 2020; 20(8):892-893. doi.org/10.1016/ S1473-3099(20)30561-2.
3. Reed N. The History of Ultraviolet Germicidal Irradiation for Air Disinfection Public Health Rep. 2010; Jan-Feb; 125(1):15–27.doi:10.1177/003335491012500105.
4. CDC Centers for Disease Control and Prevention. Healthcare Workers-Implementing Filtering Facepiece Respirator (FFR) Reuse, Including Reuse after Decontamination, When There Are Known Shortages of N95 Respirators. Updated August 4, 2020. Accessed August 27, 2020. https://www.cdc.gov/coronavirus/2019-ncov/hcp/ppe-strategy/decontamination-reuse-respirators.html​
5. Xenon LightStrike™ pulsed xenon disinfection robot. Product information. Accessed August 28, 2020. https://www.go.xenex.com/SARs-CoV-2-Results​
6. US Environmental Protection Agency Pesticide Registration. Expedited Review for Adding Electrostatic Spray Application Directions for Use to Antimicrobial Product Registrations. Accessed August 30, 2020. https://www.epa.gov/pesticide-registration/expedited-review-adding-electrostatic-spray-application-directions-use​
7. Allied BioScience’s SurfaceWise2 Press release. August 24, 2020. Accessed August 28, 2020.
8. Oh C, Araud, E, Puthussery J, Bai H, Clark G, Wang L, Verma V, Nguyen T.Dry Heat as a Decontamination Method for N95 Respirator Reuse.Environ. Sci. Technol. Lett. 2020; 7, 9, 677–682. doi: 10.1021/acs.estlett.0c00534.