Exploring the Potential of Ultraviolet Light Disinfection


Ashish Mathur, PhD: “Today, there are no uniform industry standards to evaluate the efficacy of UVC devices. The onus is up to the infection preventionist to make sure and confirm that whatever claims have been made for the device are being substantiated by clinical evidence and third-party testing.”

There’s no doubt the ultraviolet C (UVC) works, and works well when it comes to killing pathogens, Ashish Mathur, PhD, tells Infection Control Today®. Of course, he has a stake in any discussion about UVC. Mathur is the vice president for innovation and technology at a company called UVDI, which manufactures UV light devices. He agreed to talk to ICT® about the advantages of UVC in general, and not about his company or the products it sells. Pay attention because the people UVDI and other manufacturers of UVC devices pitch to are infection preventionists (IPs) and environmental services (EVS) teams. One stumbling block to integrating UVC more fully into the health care system is that there are not national standards for the devices; no government agency regulates them. Buyers must get their information from the manufacturers. Mathur wishes that there were national standards, it would make his job easier. The “onus for validation [is left] to the manufacturer … the manufacturer should be able to support whatever claims they’re making about the device. But there is no regulation,” he says. Still, Mathur says that some major health care systems have bought into UVC disinfection in a big way and that UVC is very effective against coronaviruses, including the Delta variant of COVID-19.

Infection Control Today®: Please tell me more about the potential of ultraviolet light disinfection.

Ashish Mathur, PhD: As people would probably know by now with UVC [ultraviolet C] being so prevalent in the industry, UVC light has been used extensively for more than 50 years to disinfect drinking water, wastewater, pharmaceuticals, industries, air and surfaces against a whole suite of human pathogens. All bacteria and viruses tested to date—and these are like hundreds of them—have been shown to respond to UVC light and they also show that they are very susceptible to UV light and can be damaged by UV light. I call it a gift of nature that the DNA of these microorganisms are so susceptible to UV light that they absorb the UV light and can be damaged by this wavelength which low pressure mercury lamps are putting out.

ICT®: There has been a lot of talk about UV light over the years, but it doesn’t seem that the health care system has embraced it. Is that a fair assessment?

Mathur: I would tend to disagree a little bit. I would say UVC light has been used quite prevalently in the last five years, at least, because of the issue of hospital-acquired infections [HAIs]. We know that MDROs [multidrug resistant organism] like MRSA [methicillin-resistant Staphylococcus aureus], C. diff, CLABSIs [central line-associated bloodstream infections], VRE [vancomycin-resistant enterococci], Candida auris are really a big concern in hospital settings. So UVC technology has been used as kind of a second line of defense after chemical disinfectants in these past few years. The adoption, of course, has varied across the industry, but as a technology, I believe there is enough evidence now showing that the UVC light is effective at disinfecting these MDROs.

ICT®: I’ve read the apparently it is effective. Apparently, the problem is applying it to the real world. And my read is that most hospitals do not apply it. They’ll just use the usual cleaning by the environmental services team. How can a hospital fit this into their disinfecting system at low cost, low maintenance, and low expenditure of time?

Mathur: That’s the advantage. We never recommend UVC technology to be used by itself. It is a multi-barrier approach. If the first line of defense is not sufficient or inadequate, as is the case for this current pandemic, you do need a second line of defense. For example, chemical disinfectants are applied manually in a patient room in hospital settings. And there are missed surfaces and evidence has shown that manual cleaning is only 50% effective. So, there are some surfaces and spots which are missed when these rooms are cleaned. Bringing in a UV light, which irradiates the entire surface of the room, does add a much higher level of disinfection in that room.

ICT®: Can you name some health care systems—big names like maybe Johns Hopkins or the Mayo Clinic and the Cleveland Clinic, somebody at that level—that have embraced UV light? Who has embraced UV light the best out of all the health care systems out there?

Mathur: I can’t name all our customers but from what I’ve read and studied in terms of what are the clinical studies which have been presented in the peer-reviewed literature, I would say Johns Hopkins University, the Cleveland Clinic, a lot of the VA systems. Baptist Health South Florida—that’s a big system—[the University of Pennsylvania Health System], [New York-Presbyterian Hospital], and I believe Kaiser Permanente in California. These are huge systems which have adopted UV in a big way.

ICT®: Most of my core leadership comprises infection preventionists. As you know, many of them have a nursing background. How would this help them in their job? What’s a real-world example?

Mathur: It’s all about ensuring that a patient who is occupying a room which has been previously occupied by a patient who’s carrying a MDRO, [that that room] has been sufficiently disinfected. And like I mentioned, adding UVC technology as an adjunct to manual cleaning, reduces the infectious load in a room quite significantly. And, of course, there’s peer-reviewed evidence showing that the [infectious disease] rates have also been decreased when UVC has been implemented properly and successfully in a hospital setting.

ICT®: What are some things that you’ve heard about UV light that people assume to be true which are actually inaccurate?

Mathur: Well, the first thing I would say is that there’s some misinformation out there that UVC cannot be used in occupied spaces. That is absolutely not true. The current UVC light—which is used, pretty much, in all the UV systems today—uses a wavelength of UVC light which, upon extended exposure, can temporarily damage the skin and eyes of humans. There are a couple of new technologies which are emerging which have less effect on human skin. But I would say predominantly the major application of UVC uses low pressure mercury lamps. And those can damage human eyes and skin over extended exposure time. So, that would be number one. The number two is that all UV devices are not the same. Even though you will see technology works and people know that it works, you have to make sure that people are utilizing the right amount … you’re putting out the right amount of power. If you don’t have the right amount of UV power, you’re not going to achieve the level of disinfection you need. It’s all about how the devices have been configured. One is the right wavelength of light. Some people are putting just a standard UV light and making claims which are not validated by, say, independent or third-party testing. Today, there are no uniform industry standards to evaluate the efficacy of UVC devices. The onus is up to the infection preventionist to make sure and confirm that whatever claims have been made for the device are being substantiated by clinical evidence and third-party testing.

ICT®: There’s no Food and Drug Administration (FDA) approval needed to sell a UVC device?

Mathur: This does not come out of the FDA jurisdiction. It’s not a medical device, because there is no patient contact. These devices are used to disinfect rooms, even like chemical disinfectants. It does not come under the purview of the FDA. Even the EPA [Environmental Protection Agency] does not have any regulation. They do classify UVC devices as pesticide devices; it’s in that category. They leave the onus for validation to the manufacturer, that the manufacturer should be able to support whatever claims they’re making about the device. But there is no regulation. There is no, I would say, test standard for the performance. And I am involved actively in a couple of organizations like ASHRAE [American Society of Heating, Refrigerating and Air-Conditioning Engineers], which have started to develop test standards to validate the performance of these devices.

ICT®: I gather by the way you just said that, that you kind of wish there were regulations of the devices. It might help companies, such as the one you work for, sell the devices. I mean, people might be more receptive to it. Is that fair to say?

Mathur: I would say it’s the other way around. Right now, the infection preventionist and the executives of hospitals, how do they differentiate one device from another? It’s all going to be based on what the manufacturer is saying and what claims they’re making. Because of the lack of standards, they have to kind of do that due diligence and make sure that whatever claims have been made, are backed by solid evidence.

ICT®: Does that usually fall on the infection prevention and control department in hospitals?

Mathur: I would say that the depth of evaluation is a combination of infection preventionist and EVS. It is typically the EVS department that is deploying the devices. So, not just the validation of performance, but also, “Can we use the device easily? Effectively? Is too heavy? Can I move it around because it has to go from room to room?” So, you need a device—or if it’s multiple devices that have to be used at the same time…. They have to be ergonomic. They have to be easy to operate, because most of the people who are operating them are not nurses. They’re not infection preventionists. They are the EVS people who are doing manual cleaning every day. It has to be very easy to use.

ICT®: I am trying to recall your answer to an earlier question. Did you say that the Veterans Affairs health care system seems to be embracing UV light technology a lot?

Mathur: Yes, we’ve had multiple placements in the VA system. And I know other manufacturers also have placed devices. And I’ve seen some articles and literature or press releases coming out from the VA systems.

ICT®: That segues into my next question. The VA health care system is not solely for the elderly. As you know, nursing homes were really the nexus of the COVID-19 pandemic. Do you see UV light possibly helping nursing homes out to avoid these kinds of infections? Not just COVID-19, but all kinds of infections that can happen in long-term care facilities?

Mathur: That’s a great point. And I wish that was the case. These devices are not cheap. Most of the hospitals—acute care hospitals—they are able to justify and basically buy these devices. Most of these hospitals are required to report and improve the HAI rates. They can kind of justify that, OK, using the device is not just reducing the environmental burden across the hospital, but it’s also helping drive these HAI rates down in nursing homes. On the other hand, the level of cleaning, I would say is not going to be as good as what you would find in an acute care hospital. The environmental burden of these microorganisms could be higher. But on the other hand, I think patients in nursing homes or people in nursing homes are not as sick as they would be in an acute care hospital. Of course, it’s a great technology to have, especially for the scrubbing hospitals do require. It is really effective. There’s so much evidence that has come out that UVC technology is actually so effective against SARS-CoV-2. That it is even more effective compared to SARS [severe acute respiratory syndrome] CoV and MERS [Middle East respiratory syndrome] CoV in the past. Definitely much more effective for influenza. So, to deploy a UV system in a nursing home is absolutely warranted as long as people can kind of generate the funds to purchase it. There are some devices which are less expensive, but they don’t have the power. For example, in acute care hospitals, there is pressure to turn over a room. When a patient is leaving the room and next patient is coming in, they need to turn over the room pretty quickly … like maybe in 15 minutes or 30 minutes. These devices have to work very fast. That’s why they pack a lot of UV light on it so that they can disinfect in a very short period of time. Some of the less expensive devices will take longer, but they would still be effective.

ICT®: Doctor Mathur, is there something that I neglected to ask you that you think is pertinent to this conversation that you’d like to add?

Mathur: People are talking about the Delta variant right now. Right? The alpha and the beta variants … that’s what was typically tested in the field, right? So, for example, our device was tested in a [Biosafety Level 3] lab showing that, OK, you can get 99.99% disinfection in very quick, short period of times. But the question is asked, “Hey, is it also effective against the Delta variant?” And my answer is absolutely. And I think that’s the beauty of UVC light. The Delta variant has a different spike protein compared to the previous variants, but the core RNA structure is still the same. And how UVC works is it goes and penetrates this RNA structure and damages the RNA. That’s the backbone of the virus, and it breaks it down. It doesn’t really depend so much on what the spike proteins are. The mechanism of inactivation is really that it goes and breaks down the RNA structures. So as long as it’s not completely mutated, and the RNA structure is pretty much the same, UVC is going to be effective against the Delta variant. Most of these differences are really on the surface, the spike proteins and how they are arranged. The good thing is that viruses are, I would say, the easiest to inactivate compared to say some other bacteria and spores and mold for UVC.

This interview has been edited for clarity and length.

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