Infection Prevention and Control/Surface Decontamination

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Surface Disinfection for SARS-CoV-2

Ultraviolet Germicidal Irradiation

UV-C air disinfection was been explored extensively in the context of TB infection prevention and control by the South African scientific community in association with international experts. National Technical Standards, Protocols, guidelines and testing capacity for application of upper-room UVGI in airborne transmission have been established[1]. This experience has provided important basic knowledge and key insights into the underpinning science and theory as well as application constraints, albeit for a different application.

Introduction

The coronavirus, SARSs-CoV-2, is understood to be transmitted primarily by contact and droplet spread[2].

Covid-19 is highly contagious and spreads more rapidly than its predecessors Severe Acute Respiratory Syndrome (SARS-Cov-1) and Middle East Respiratory Syndrome (MERS)</ref>[3], so any residual contamination can pose a public health threat[3]. COVID-19 transmission remains controversial as researchers across the globe remain conflicted about droplet and airborne as modes of transmission[3]. Clarifying the transmission routes and survival of viruses on frequently used surfaces is essential for containment of the outbreak. Research has successfully demonstrated that the virus has the potential to be aerosolised[4], and therefore can theoretically opportunistically transmit through the airborne route, it is understood that, except in aerosolising procedures, risk of coronavirus transmission via the airborne route [5] is low. Similarly, risk via water and wastewater is low [6]. Persistence of the virus on a variety of surfaces has been demonstrated [4], underpinning concern that SARS-CoV-2 may be transmitted from infected (even asymptomatic) persons to others from touching common surfaces, even after the infector has departed for several hours [7][8]. Efforts to contain the coronavirus, to stem the pandemic, should therefore primarily focus on contact and droplet transmission. Contact and droplet transmission is of concern in public transport systems taxis which convey very large transient populations is normally congested conditions, such as in trains and mini-bus taxis. Transfer of suspected or confirmed Covid-19 patients in planned transport or emergency service vehicles poses a risk since studies show that conventional decontamination procedures may be inadequat[5]. In a pandemic, and within already constrained healthcare infrastructure, overcrowding and close proximity of infectious and susceptible individuals will become highly. These conditions will amplify the risk of Covid-19 transmission.

In the South African context, the reduction of exposure to Covid-19 is a priority, in order to:

  • reduce and delay occupational exposure of frontline workers especially healthcare and transport services workers;
  • reduce exposure to public health risk, especially to the most vulnerable, such as PLHIV and persons with TB who are the principal users of public transport;
  • contribute to the strategy of “flattening the curve”; and
  • preserve and protect the healthcare service so as to ensure continued service.

This article proposes UV-C surface disinfection for reducing contact and droplet transmission of SARS-CoV-2 through the following applications:

  1. Portable disinfection devices for use in the transport sector (minibus taxis, trains and emergency and planned patient transport)
  2. Public Spaces
  3. Commercial and industrial occupational settings
  4. Decontamination of personal and respiratory protection equipment

UV-C: potential for disinfection for SARS-CoV-2

The disinfection effect of ultraviolet light has been described for over 100 years[9]. It is effective against a variety of microorganisms and has been successfully deployed for the purpose of disinfection of water, air and surfaces. Effectiveness depends on a range of variables related to the microorganism of interest, environment and application. Ultraviolet radiation in the UV-C range has been used for its germicidal properties specifically for infection prevention and control - have been demonstrated to work at laboratory scale, in ducts, as upper room irradiation and as portable devices. Safety guidelines have been established (ACGIH)[3]. There is good reason to expect that SARS-CoV-2 will be susceptible to UV-C. UV-C, when applied at the correct dose as it has been found effective against influenza viruses [10]including human coronavirus [11][12] (SARS-CoV-1).

According to Kowalski et. al. [13], Covid-19 is susceptible to existing disinfection methods such as chemicals and exposure to ultraviolet radiation in the electromagnetic range ~ 200 – 280nm (UV-C) because of the similarity of its structure to other susceptible coronaviruses such as SARS-CoV-1 and MERS.

UVGI surface disinfection has advantages over chemical disinfection because:

  • There is no off-gassing of chemicals or residual chemical contamination frequently associated with chemical-based disinfection methods. Therefore, vehicles or spaces can be occupied immediately after UVGI disinfection[14];
  • It has high pathogen reduction rates when compared to chemical cleaning; and
  • Chemical disinfection methods are time-consuming [15].

A guideline on hospital infection control [16][17] recommends the use of both UVGI and chemical disinfection since UVGI has no penetrating power on dust, dirt and grease, which may harbour microbial contamination. Exposure to UV-C may degrade some materials.

As SARS-CoV-2 is recent and novel, UVGI efficacy has not yet been conclusively established against this particular pathogen[3]. For the reasons stated above, UVGI – the exposure of potentially contaminated contact surfaces to UV-C is identified as a measure with good prospects to reduce and delay occupational exposure of healthcare and transport services workers, as well as their clientele, and to contribute to the strategy of “flattening the curve”.

Approaches to UVGI surface disinfection

The application of UVGI for surface disinfection usually involves the use of bare UVGI lamps. Two main approaches to surface disinfection systems are via permanently installed disinfection systems and portable disinfection systems. Permanently installed systems generally consist of bare UVGI lamp fixtures mounted on ceilings or walls. Portable UVGI systems are moved into a place temporarily to decontaminate surfaces [14]. Efficacy is dependent on the intensity of irradiation emitted from the device, proximity of the device to the surface being disinfected and exposure time. The reflectivity of the materials in the vicinity of exposure can increase or decrease efficacy. Shaded items not directly exposed to UV-C irradiation may not effectively be disinfected

Case Studies

Moscow trains

In Moscow, Russia, Kostyuchenko, et. al., [15], investigated the potential of UVGI disinfection on internal surfaces of train carriages and on escalator handrails. They found that the required UV doses for effective disinfection are higher than the theoretically calculated doses.

Ambulance decontamination [3]

Respiratory Protective Equipment decontamination [3]

Notes and References

  1. ↑ https://www.tb-ipcp.co.za/tools-resources/uvgi-documents/national-guidelines-abridged
  2. ↑ WHO 2020 Modes of transmission of the virus causing COVID-19: implications for IPC precaution recommendations https://www.who.int/news-room/commentaries/detail/modes-of-transmission-of-virus-causing-COVID-19-implications-for-ipc-precaution-recommendations
  3. ↑ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 Citation Needed
  4. ↑ 4.0 4.1 van Doremalen, N, Bushmaker, T, and Morris, DH e.tal Aerosol and Surface Stability of SARS-CoV-2 as Compared with SARS-CoV-1. New England Journal of Medicine. March 17, 2020 [1]
  5. ↑ 5.0 5.1 Lindsley, W.G, McLelland, T.L. and Neu, D.T. et. al. 2018. Ambulance Disinfection using Ultraviolet Germicidal Irradiation (UVGI): Effects of Fixture Location and Surface Reflectivity. [2]
  6. ↑ Steyn, M. (2020, April 8). Summary notes of the International Water Association (IWA) Webinar: “Covid-19: A Water Professional’s Perspective”. Infrastructure Guidance for COVID-19/Alternate Care Sites/COVID-19 A Water Professionals Perspective
  7. ↑ Cai et al, 2020, Indirect Virus Transmission in Cluster of COVID-19 Cases, Wenzhou, China, 2020, Emerging Infectious Diseases, 2020, https://wwwnc.cdc.gov/eid/article/26/6/20-0412_article
  8. ↑ Le et al, 2020, Asymptomatic and Human-to-Human Transmission of SARS-CoV-2 in a 2-Family Cluster, Xuzhou, China, Emerging Infectious Diseases, 2020, https://wwwnc.cdc.gov/eid/article/26/7/20-0718_article
  9. ↑ Downes, Arthur; Blunt, Thomas P. (19 December 1878). https://royalsocietypublishing.org/doi/pdf/10.1098/rspl.1878.0109
  10. ↑ Bean B, Moore EM, Sterner B, Peterson LR, Gerding DN, Balfour HH Jr. Survival of influenza viruses on environmental surfaces. J lnfect Dis 1982;146:47-51.
  11. ↑ Ijaz et al, 1985, Survival characteristics of airborne human coronavirus 229E. J Gen Virol. 1985 Dec;66 ( Pt 12):2743-8. https://www.ncbi.nlm.nih.gov/pubmed/2999318
  12. ↑ Lai MY, Cheng PK, Lim WW. Survival of severe acute respiratory syndrome coronavirus. Clin lnfect Dis 2005 https://www.ncbi.nlm.nih.gov/pubmed/16142653
  13. ↑ Wladyslaw J. Kowalski, Thomas J Walsh, 2020. COVID-19 Coronavirus Ultraviolet Susceptibility. Technical Report · March 2020. [3]
  14. ↑ 14.0 14.1 Wladyslaw Kowalski, 2009. Ultraviolet Germicidal Irradiation Handbook: UVGI for Air and Surface Disinfection. New York. Springer. [4]
  15. ↑ 15.0 15.1 Sergey Kostyuchenko, Anna Khan, Sergey Volkov, Henk Giller, 2009. UV Disinfection in Moscow Metro Public Transport Systems. IUVA News / Vol. 11 No. 1 [5]
  16. ↑ Brown IW Jr et al (1996) Toward further reducing wound infections in cardiac operations. Ann Thorac Surg 62(6):1783–1789.[6]
  17. ↑ Shamim, I. A. ed., 2017. Ultraviolet Light in Human Health, Diseases and Environment. Cham, Switzerland: Springer International Publishing AG.[7]
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