2020 COVID-19 Coronavirus Ultraviolet Susceptibility

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DOI: 10.13140/RG.2.2.22803.22566 ·
Report number: COVID-19_UV_V20200312
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Abstract
This report addresses a topic of high current interest - the ultraviolet susceptibility of SARS-CoV-2, the virus that causes COVID-19 disease. The results of a literature review are presented and summarized to provide a basis for estimating the ultraviolet susceptibility of SARS-CoV-2, and relevant supplemental information is provided on COVID-19 based on the latest published reports. A discussion on the feasibility of using the new technology of Focused Multivector Ultraviolet light as a disinfection strategy is included.
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2020 COVID-19 Coronavirus Ultraviolet Susceptibility
Memo from the Authors
The current global Coronavirus pandemic is of urgent concern with its high transmission rate and rapid
spread throughout the world. The current reported death rate is 2-3% and there currently is no antiviral
drugs or vaccine available to the public. Structurally, this virus is not unique and is similar to other
coronaviruses such as Severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome
(MERS), and can be addressed with existing disinfection methods such as chemicals and new
technologies such as Focused Multivector Ultraviolet (FMUV) from PurpleSun.
Answers to Frequently Asked Questions
1. How long does COVID-19 Live on Surfaces?
6 hours - 9 days on surfaces
2. What is the difference between a virus and bacteria?
Bacteria are self-contained, have cell walls, and can survive and replicate on their own.
Viruses are DNA molecules that may be naked or encapsulated and require a host to replicate.
They cannot be treated with antibiotics and require a vaccine
3. What is the biggest issue with this COVID-19 virus?
High secondary infection rate, Rapid spread (more rapid than SARS or MERS), Fatality rate (2-
3%)
4. Is ultraviolet light effective against COVID-19?
Ultraviolet light destroys DNA of viruses, bacteria, and fung
5. What is the appropriate Personal Protective Equipment (PPE) for healthcare staff?
https://www.cdc.gov/coronavirus/2019-ncov/downloads/COVID-19-PPE.pdf
General Explanation of the Disease
COVID-19 is the respiratory disease caused by the SARS-CoV-2 virus that has caused outbreaks
worldwide. The SARS-CoV-2 is a new variant in the betacoronavirus family (Fisher 2020). It transmits by
direct contact or contact with fomites and can be suspended in air as well, as are the related
betacoronaviruses SARS, MERS, and the four known Human coronaviruses OC43, 229E, NL63, and
HKU1. The majority of infection transmissions are believed to be by droplet spray from coughing and
sneezing and by direct contact or contact with fomites.
Confirmation That Ultraviolet is Effective
Ultraviolet light can be an effective measure for decontaminating surfaces that may be contaminated by
the SARS-CoV-2 virus by inducing photodimers in the genomes of microorganisms. Ultraviolet light has
been demonstrated to be capable of destroying viruses, bacteria and fungi in hundreds of laboratory
studies (Kowalski 2009). The SARS-CoV-2 virus has not yet been specifically tested for its ultraviolet
susceptibility but many other tests on related coronaviruses, including the SARS coronavirus, have
concluded that they are highly susceptible to ultraviolet inactivation. This report reviews these studies and
provides an estimate of the ultraviolet susceptibility.
It is estimated that the SARS-CoV-2 virus can survive on surfaces for up to 9 days, based on its similarity
to SARS and MERS. Standard disinfectants are effective against SARS-CoV-2 but as an extra level of
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protection, and to shield against errors in the manual disinfection process, ultraviolet light can be used to
disinfect surfaces and equipment after the manual chemical disinfection process is completed. ASHRAE
recommends ultraviolet germicidal irradiation as one strategy to address COVID-19 disease transmission
(ASHRAE 2020).
COVID-19 is highly contagious and so any residual contamination, no matter how small, can pose a threat
to healthcare workers and patients. The PurpleSun E300 Focused Multivector Ultraviolet (FMUV) system
with Shadowless DeliveryTM (see Figure 1) is an automated system that has proven to reduce surface
contamination by 96% and can address contamination left behind by current manual chemical cleaning
which was shown to only reduce contamination by 36% (Armellino 2020).
The PurpleSun E300 system has demonstrated elimination of 99%-99.99% of bacteria and fungi as listed
in Table 2 in laboratory tests within 90 seconds (Petraitis 2017). Similar reductions could be expected
against the COVID-19 coronavirus in 90 seconds as well.
Scientific Rationale
Coronaviruses are members of the Coronaviridae group and contain a single-stranded, positive-sense
RNA genome surrounded by a corona-like helical envelope (Ryan 1994). Approximately 100 sequences
of the SARS-CoV-2 genome have been published and these suggest there are two types, Type I and
Type II, of which the latter came from the Huanan market in China while the Type I strain came from an
unknown location (Zhang 2020). The genome consists of 29,751 base pairs (NC_045512.2) and the
genome is about 80% homologous with SARS viruses (NCBI 2020, Fisher 2020). Coronaviruses have a
size range of 60-140nm, with a mean size of 0.10 microns (Zhu 2020).
Table 1 summarizes the results of studies that have been performed on Coronaviruses under ultraviolet
light exposure, with the specific species indicated in each case. The D90 value indicates the ultraviolet
dose for 90% inactivation. Although there is a wide range of variation in the D90 values, this is typical of
laboratory studies on ultraviolet susceptibility. The range of D90 values for coronaviruses is 7-2410 J/m2
and the average of all studies is 237 J/m2. However, the study by Walker (2007) is an airborne study and
is an outlier in this set of water-based studies. Also, the studies by Weiss (1986) and Darnell (2004) are
outliers on the low and high ends. Excluding outliers, the mean D90 is 47 J/m2, and this should
adequately represent the ultraviolet susceptibility of the SARS-CoV-2 (COVID-19) virus.
Two recent studies on SARS-CoV-2 have been added to Table 1 (Inagaki 2020, Bianco 2020). The
average value of the D90 is 27 J/m2, which suggests the average value for all coronaviruses reported
above (47 J/m2) is conservative. Both of these studies indicate tailing in the survival curve above about 3-
6 logs of reduction, beyond which the D90 value will not be an accurate predictor (Blatchley 2020).
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Microbe
D90 Dose
J/m2
UV k m2/J Base Pairs kb Source
Coronavirus 6.6 0.35120 30741
Walker 2007a
Berne virus (Coronaviridae) 7.2 0.32100 28480 Weiss 1986
SARS-CoV-2 (Italy-INMI1) 12.3 0.18670 29811 Bianco 2020
Murine Coronavirus (MHV) 15.0 0.15351 31335 Hirano 1978
SARS Coronavirus (Frankfurt 1) 16.4 0.14040 29903 Eickmann 2020
Canine Coronavirus (CCV) 28.5 0.08079 29278
Saknimit 1988b
Murine Coronavirus (MHV) 28.5 0.08079 31335
Saknimit 1988b
SARS Coronavirus (CoV-P9) 40.0 0.05750 29829
Duan 2003c
SARS-CoV-2 (SARS-CoV-2/Hu/DP/Kng/19-027) 41.7 0.05524 29811 Inagaki 2020
Murine Coronavirus (MHV) 103.0 0.02240 31335 Liu 2003
SARS Coronavirus (Hanoi) 133.9 0.01720 29751
Kariwa 2004d
SARS Coronavirus (Urbani) 2410 0.00096 29751 Darnell 2004
Average 237 0.00972
Average excluding outliers 47 0.04943
Average for SARS-CoV-2 27 0.08528
a(Jingwen 2020) b(estimated) c(mean estimate) d(at 3 logs)
Table 1: Summary of Ultraviolet Studies on Coronaviruses
including all studies
excluding Walker, Weiss & Darnell
two studies, 90% inactivation
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Figure 1: The PurpleSun E300 FMUV system in PACT configuration for transport or storage
(Left), CUBE configuration for surrounding smaller equipment (Center), and RECTAN mode for
surrounding larger equipment (Right).
Updated on July 7, 2020 by:
Dr. Wladyslaw J. Kowalski, PhD, Chief Scientist and World UV Expert, PurpleSun Inc
Research@purplesun.com
Dr. Thomas J. Walsh, MD, PhD, Infectious Diseases Translational Research Laboratory, Weill Cornell
Medicine of Cornell University, New York City, NY
Dr. Vidmantas Petraitis, MD, Infectious Diseases Translational Research Laboratory, Weill Cornell
Medicine of Cornell University, New York City, NY
2015: https://www.researchgate.net/publication/284691618_SARS_Coronavirus_UV_Susceptibility
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3. ASHRAE. (2020). ASHRAE Resources Available to Address COVID-19 Concerns. (American Society of
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21-21 41st Ave, Suite 5B, Long Island City, NY 11101
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    In December 2019, a cluster of patients with pneumonia of unknown cause was linked to a seafood wholesale market in Wuhan, China. A previously unknown betacoronavirus was discovered through the use of unbiased sequencing in samples from patients with pneumonia. Human airway epithelial cells were used to isolate a novel coronavirus, named 2019-nCoV, which formed another clade within the subgenus sarbecovirus, Orthocoronavirinae subfamily. Different from both MERS-CoV and SARS-CoV, 2019-nCoV is the seventh member of the family of coronaviruses that infect humans. Enhanced surveillance and further investigation are ongoing. (Funded by the National Key Research and Development Program of China and the National Major Project for Control and Prevention of Infectious Disease in China.).
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    Aims: To develop a new mathematical model derived from first principles to define the kinetics of ultraviolet disinfection and to explain the phenomenon known as tailing. The theory presented interprets tailing as the result of photoprotection due to cumulative Mie scattering effects in clustered populations of microorganisms. Methods and results: Mie scattering effects at ultraviolet wavelengths are used to compute a Shielding Constant for each microorganism based on the Average Projected Diameter. An Intrinsic Rate Constant, hypothesized to be a characteristic property of the microbial genome alone, is computed. The Cluster Model is fitted to tailing data from 30 ultraviolet inactivation studies and results are compared with the classic Two Stage Multihit Model. Conclusions: The Cluster Model demonstrates a statistically significant improvement in the mean adjusted R2 values of the tested data sets (p < 0·0001). Tailing in survival curves is the direct consequence of the Gaussian distribution of cluster sizes and the Intrinsic Rate Constant is a real and critical parameter that defines ultraviolet susceptibility. Significance and impact of the study: The ultraviolet dose-response behavior of microorganisms can now be explained in terms of parameters that have physical meaning and that provide deep insight into the disinfection process.
  • Article
    Background: The aim of this study was to evaluate the performance of a focused multivector ultraviolet (FMUV) system employing shadowless delivery with a 90-second disinfection cycle for patient care equipment inside and outside the operating room (OR) suite without manual-chemical disinfection. Methods: A 5-point multisided sampling protocol was utilized to measure the microbial burden on objects inside and outside the OR environment in a 3-phase nonrandomized observational study. Surface sampling was performed pre- and postdisinfection in between cases (IBCs) to assess the performance of manual-chemical disinfection. FMUV system performance was separately assessed pre- and postdisinfection before the first case and IBCs. Additionally, visibly clean high-touch objects were sampled outside the OR, and the microbial burden reductions after FMUV disinfection were quantified without manual-chemical disinfection. Results: Manual-chemical disinfection reduced the active microbial burden on sampled objects IBCs by 52.8%-90.9% (P <.05). FMUV reduced the active microbial burden by 92%-97.7% (P <.0001) before the first case and IBCs combined, and 96.3%-99.6% (P <.0001) on objects outside the OR without chemical disinfection. Conclusions: Five-point multisided sampling proved effective for assessing disinfection performance on all exterior sides of equipment. FMUV produced significant overall reductions of the microbial burden on patient care equipment in all study phases and independent of manual cleaning and chemical disinfection. (Please contact Dr. Kowalski directly for a PDF of this article)
  • Article
    Full-text available
    Disinfection by low-pressure monochromatic ultraviolet (UVC) radiation (253.7 nm) became an important technique to sanitize drinking water and also wastewater in tertiary treatments. In order to prevent the transmission of waterborne viral diseases, the analysis of the disinfection kinetics and the quantification of infectious viral pathogens and indicators are highly relevant and need to be addressed. The families Adenoviridae and Polyomaviridae comprise human and animal pathogenic viruses that have been also proposed as indicators of fecal contamination in water and as Microbial Source Tracking tools. While it has been previously suggested that dsDNA viruses may be highly resistant to UVC radiation compared to other viruses or bacteria, no information is available on the stability of polyomavirus toward UV irradiation. Here, the inactivation of dsDNA (HAdV2 and JCPyV) and ssRNA (MS2 bacteriophage) viruses was analyzed at increasing UVC fluences. A minor decay of 2-logs was achieved for both infectious JC polyomaviruses (JCPyV) and human adenoviruses 2 (HAdV2) exposed to a UVC fluence of 1,400 J/m2, while a decay of 4-log was observed for MS2 bacteriophages (ssRNA). The present study reveals the high UVC resistance of dsDNA viruses, and the UV fluences needed to efficiently inactivate JCPyV and HAdV2 are predicted. Furthermore, we show that in conjunction with appropriate mathematical models, qPCR data may be used to accurately estimate virus infectivity.
  • Book
    This book is a comprehensive source for technical information regarding ultraviolet germicidal irradiation (UVGI) and its application to air and surface disinfection for the control of pathogens and allergens. The primary focus is on airborne microbes and surface contamination applications for hospitals, commercial facilities, and residential homes. All aspects of UVGI systems, including design methods, sizing methods, modeling, safety, installation, testing, guidelines, and disinfection theory are addressed in detail. An extensive database of over six hundred UV rate constant studies is included as well as tabular performance data for UV lamps and products. Providing this information in one single source simplifies the design and installation of UVGI systems, helps guarantee effective performance of new systems, and facilitates their use on a wide scale for the purpose of improving human health. This book is organized to provide systematic coverage of all related issues and will serve equally well as both a textbook and a handbook for general reference.
  • Article
    Some properties of a strain of mouse hepatitis virus, MHV-2, grown on DBT cells were determined using a plaque assay on the cells. Viral growth was not inhibited by the presence of actinomycin D or 5-iodo-2-deoxyuridine. MHV-2 was completely inactivated by ether, chloroform, sodium deoxycholate or beta-propiolactone, but showed a moderate resistance to trypsin. Heating at 56 C for 30 min did not completely abolish the virus infectivity. The virus was stable after heating at 50 C for 15 min in 1M-MgCl2 or 1M-MgSO4 as well as at 37 C for 60 min at pH 3.0 to 9.0. Infectivity was decreased to 1/100 and 1/400 after storing at 4 C for 30 days and 37 C for 24 hr, respectively. The virus passed through a 200-nm but not a 50-nm Sartorius membrane filter. The buoyant density of MHV-2 was 1.183 g/cm3 in sucrose gradient, and the fraction contained coronavirus-like particles measuring 70 to 130 nm in diameter. Survival rate was 10% after exposure to ultraviolet at 150 ergs/mm2. Freezing and thawing or sonication at 20 kc for 3 min did not affect the virus titer. No hemagglutinin was demonstrable with red blood cells of the chicken, Japanese quail, mouse, rat, hamster, guinea pig, sheep, bovine or human.
  • Article
    Virucidal efficacy of chemical disinfectants, heating and ultraviolet radiation against mouse hepatitis virus (MHV), canine coronavirus (CCV), Kilham rat virus (KRV) and canine parvovirus (CPV) were examined. Coronaviruses (MHV and CCV) were inactivated by ethanol, isopropanol, benzalkonium chloride, iodophor, sodium hypochlorite, sodium chlorite, cresol soap and formaldehyde as well as by heating at 60 degrees C for 15 minutes, whereas parvoviruses (KRV and CPV) appeared to be inactivated by disinfectants such as formaldehyde, iodophor, sodium hypochlorite and sodium chlorite. Parvoviruses were stable under heating of up to 80 degrees C for 30 minutes. Ultraviolet radiation inactivated all viruses within 15 minutes. No significant differences in stability against physico-chemical treatments were seen between viruses in the same group.