key: cord-0796277-8rl0y45s
authors: Cimolai, Nevio
title: Environmental and Decontamination Issues for Human Coronaviruses and Their Potential Surrogates
date: 2020-06-12
journal: J Med Virol
DOI: 10.1002/jmv.26170
sha: 52aa29c5d71d6d05ea26cb45d4faf424a7888f7e
doc_id: 796277
cord_uid: 8rl0y45s

Pandemic COVID‐19 gives ample reason to generally review coronavirus (CoV) containment. For establishing some preliminary views on decontamination and disinfection, surrogate CoVs have commonly been assessed. This review serves to examine the existing science in regards to CoV containment generically and then to translate these findings into timely applications for COVID‐19. There is widespread dissemination of CoVs in the immediate patient environment, and CoVs can potentially be spread via respiratory secretions, urine, and stool. Interpretations of the spread however must consider whether studies examine for viral RNA, virus viability by culture, or both. Pre‐symptomatic, asymptomatic, and post‐fourteen day virus excretion from patients may complicate the epidemiology. Whereas droplet spread is accepted, there continues to be controversy over the extent of possible airborne spread and especially now for SARS‐CoV‐2. CoVs are stable in body secretions and sewage at reduced temperatures. In addition to temperature, dryness or relative humidity, initial viral burden, concomitant presence of bioburden, and the type of surface can all affect stability. Generalizing, CoVs can be susceptible to radiation, temperature extremes, pH extremes, peroxides, halogens, aldehydes, many solvents, and several alcohols. Whereas detergent surfactants can have some direct activity, these agents are better used as complements to a complex disinfectant solution. Disinfectants with multiple agents and adverse pH are more likely to be best active at higher water temperatures. Real‐life assessments should be encouraged with working dilutions. The use of decontamination and disinfection should be balanced with considerations of patient and caregiver safety. Processes should also be balanced with considerations for other potential pathogens that must be targeted. Given some CoV differences and given that surrogate testing provides experimental correlates at best, direct assessments with SARS‐CoV, MERS‐CoV, and SARS‐CoV‐2 are required. This article is protected by copyright. All rights reserved.

samples were obtained from air in patient rooms, bathroom, and common corridor. 60 PRCV could be cultured from air samples during experimental porcine infection containment. 61 TGEV remained in an airborne state during experimental infection. 62 For PEDV, viral RNA could be detected up to ten miles downwind from infected herds, and live virus could be detected in air some 1.2 meters above experimentallyinfected swine. 63 Early studies for SARS-CoV-2 also support aerosol transmission. [64] [65] [66] [67] Aerosolization studies support the concept that virus is viable in aerosols for up to three hours. 65 In ferret experiments, uninfected and separated animals could acquire infection from infected animals in the same general confines. 66 Using techniques detecting viral RNA, SARS-CoV-2 could be found in air for 12.5-35% of the samples. 64 The latter included the finding of viral genome up to 2.5-4 meters away from the source and in air from the patient corridor and contiguous doctors' office. In contrast, Wu et al did not find viral RNA in a large number of air samples. 68 Liu and colleagues however detected considerable viral RNA in aerolsols. 69 They measured greater quantitations in high traffic environments and also found diminution when decontamination efforts were applied. Chia and colleagues found SARS-CoV-2 RNA in particles ranging 1->4 micrometers size within an intensive care unit and among isolations rooms elsewhere even though there was apparent adequate air exchange implemented. 67 Smither et al. examined experimental aerosols of either a saliva construct or tissue culture medium and found that particles of 1-3 micrometers could carry virus. 70 Viable virus could be detected up to ninety minutes. The experimental This article is protected by copyright. All rights reserved.

finding that surgical mask partition could reduce animal model transmission speaks highly to the potential for aerosol spread and potentially airborne transmission. 71 There are both logistic and etymological issues in understanding airborne spread. Like most if not all respiratory viruses, droplet spread occurs within a distance of approximately a metre from the patient source. 72 The latter is not absolute but a generalization. Risk increases proportionate to patient proximity. 73, 74 CoVs are certainly capable of spread within such distance, but a concern is whether these viruses spread beyond the latter measures. 'Airborne spread' is usually used to convey the potential for wider and more distant dissemination for microbes exemplified by varicella-zoster virus, Mycobacterium tuberculosis, and Coxiella burnetii and for certain spore transmissions. The latter occurs with either small particles, dried microbe, or mobile spores. Isolation precautions have been more stringent for the latter than would be for typical respiratory viruses such as cold viruses or respiratory syncytial virus. Given the severity of SARS-CoV, MERS-CoV, and SARS-CoV-2 infections, there is concern whether more stringent airborne precautions should be maintained even when high-risk aerosolizing procedures are not being conducted. There is no doubt that the environmental spread discussed below can assure that virus is mobilized from sentinel sources by attendees especially healthcare workers. It appears that SARS-CoV-2 can be aerosolized and transferred for a longer distance than was originally assumed with other CoVs. 64 In effect, the airborne transmission is one of intermediacy as contrasted to conventional thoughts of how airborne transmission should be defined. The airborne transmission of PEDV as This article is protected by copyright. All rights reserved.

discussed above must also be seen in the context of the viral burden that is created when large herds of infected animals are pooled. 63 The topic of airborne transmission will continue to attract controversy and rightfully so. [75] [76] [77] In the context of discussing airborne spread, it is critical to remember that high touch surface contamination can occur regardless, and the potential for the latter to transmit virus can confuse the overall assessment. 67

In respiratory samples, SARS-CoV has been found for 4-7 days at room temperature and nearly three weeks in refrigeration. 78, 79 It can also survive the milieu of feces for up to 3-4 days especially if the sample is alkaline. [78] [79] [80] The timing for SARS-CoV stability in urine has ranged from 3-17 days. 79, 80 For all CoVs, cold temperature has a stabilizing effect.

Surrogate CoVs have been used to assess survival on samples that mimic healthcare spaces. TGEV was found to survive on samples of gloves and hospital scrub dress for up to four hours and on N95 respirator and gown material for up to 24 hours. 81 TGEV and MHV survived on stainless steel templates for days to weeks at room temperature and longer under refrigeration. 82 Ambient humidity affected the latter. At room temperature, TGEV survived for much lesser time in the light than in the dark. 83 229E showed temperature-dependent viability in buffer and suffered at higher ambient temperature. 84 The virus remained viable for up to five days at room temperature on surface materials such as polytetrafluoroethylene (Teflon), polyvinyl chloride, ceramic tiles, glass, silicone rubber, and stainless steel. It was susceptible to various copper alloys. 85 In another study, 229E was detectable for over three hours on aluminum, latex gloves, and sterile sponge, whereas OC43 appeared to be more susceptible. 86 Spontaneous inactivation of live 229E occurred on stainless steel, hard plastic, and glass over one week, but viable virus continued to be found. 87 NL63 was unstable on dry surfaces, but viral RNA could be detected for up to one week. 88 SARS-CoV was more stable on disposable gown material than cotton, but was unstable on paper. 78 The virus was more labile in a dry environment and higher ambient temperature. 89 Viral RNA could be found in the emergency room setting on drinking fountains, bedside chair, table top, bedding, and book shelves. 90 The latter foci occurred both in areas with SARS-CoV patients and in presumed clean areas.

Another study found viral RNA widely in patient rooms, nursing stations, and the emergency department, although viral cultures were negative. 91 The latter study also found viral RNA on a hospital public area elevator hand rail. The association of mask use with protection from SARS as assessed serologically is also consistent with aerosol spread. 92 MERS-CoV RNA could be found widely on fomites and fixed surface samples in patient rooms. 60, 93 Viral RNA could yet be found after some surface cleaning with alcohol. 93 The virus survived on plastic and steel surfaces for up to 24 This article is protected by copyright. All rights reserved.

hours, although it was variably affected by ambient humidity. 94 Viable virus could be found on medical equipment, whereas viral RNA could be found both in patient rooms and the anteroom. 95 One study of SARS-CoV-2 did not find viral RNA in the immediate patient environment nor on personal protective equipment. 96 Another study from a tertiary care hospital in Wuhan, China also did not find virus in the environment. 97 After disinfection, viral RNA could not be found in one patient's rooms. 98 The latter data has now been supplemented by further study, and viral RNA is ubiquitous on environmental surface sampling from medical rooms. 67, 68, 99, 100 There is some variation in the nature and distribution of such environmental contamination, but this would be expected given the heterogeneity of healthcare settings. The finding of major floor contamination is often underappreciated. 67 Jiang et al. have also extended the findings of viral RNA to quarantine rooms elsewhere. 101 The degree of infectivity of such spread remains to be precisely defined, but early indications from the publication of Chin and colleagues represent some initial findings which differentiate live and non-infectious virus in these environments. 102 The latter study also found infectious virus remnants on the outer layer of a surgical mask by one week after inoculation. It is important, however, to recognize that a high titre of virus was initially applied. Fischer et al. have more recently examined decontamination processes for reuse of N95 respirators and report that several methods can be efficacious against SARS-CoV-2. 103 The integrity of the respirator must be closely monitored nonetheless. This article is protected by copyright. All rights reserved.

Both TGEV and MHV were stable in settled sewage water for many days at room temperature, and the stability could be extended considerably at refrigeration temperature. 104 Although SARS-CoV was not detected in sewage directly, experimental seeding of sewage allowed for virus survival up to two days at 20 o C, and viral RNA could be detected over one week at the same temperature. 105 Refrigerated, the virus could remain viable for up to two weeks. 105 In another study, SARS-CoV RNA could be found in sewage before and after chlorine treatment, but viable virus was never detected. 106 Under experimental conditions, SARS-CoV could survive in domestic sewage for two days, and viral RNA could be detected for one week. 80 SARS-CoV-2 has been found in sewage with molecular techniques although not viable. 96 Viral RNA was found in wastewater intake at treatment plants but not in tertiary effluent. 107 

TGEV and MHV were stable in cold lake water and reagent-grade water for over one month, while lesser titres were found for up to three weeks when maintained at room temperature. 104 SARS-CoV has shown stability in soil and potable water. 79 OC43 RNA was found with amplification methods on various surfaces during an airport surveillance including luggage boxes, stair rails, and payment buttons. 108 This article is protected by copyright. All rights reserved.

PEDV RNA could be found both before and after disinfection from loading vehicles. 109 Several empty vehicles newly arriving to transport swine were found to have viral RNA in the latter analysis. Susceptibility of PEDV to environmental factors such as natural UV light and/or sunlight otherwise was suggested by the finding of less viral load in top layers of manure storage in contrast to deeper layers. 110 Live virus could be found in the latter milieu for up to nine months. These studies illustrate the ability for such a virus to remain in the context of very high bioburdens.

Whether for surfaces or individualized items, decontamination of the environment can occur through a variety of potential methods. The validation for many of these approaches is variable even though some authorities have set some standards for assessment. [111] [112] [113] Such assessments include carrier tests, suspension studies, susceptibility of viable counts otherwise, detection of viral load through genetic amplification and detection, and field studies. Many such assessments do not test reallife situations but are rather generalized determinations of efficacy. For viruses in particular, there are many factors that affect the efficacy of a decontaminating agent.

In the least, these include the initial virus titre, viral species, concomitant presence of more than one virucide, contact time, working dilution, pH, temperature, dry or wet state, relative humidity, concomitant bioburden, nature of the surface, and inactivation of the test agent by the materials. Contact times in practical use are often not fully considered. For example, the contact time after floor mopping or inanimate This article is protected by copyright. All rights reserved.

object wiping are characteristically brief and measured in less than one minute.

Regardless of product residue, the decontaminated surface may also be unevenly exposed.

As viable virus is often determined through tissue culture methods, the residuum of the decontaminating agent may affect tissue culture eukaryotic cells directly. Such toxicity requires neutralization or removal through a variety of approaches prior to the detection of virus in tissue culture. 86, [114] [115] [116] [117] [118] [119] [120] [121] [122] The latter issue is critical to some determinations of efficacy. 102 As illustrated with the caution provided by Chin et al. studying SARS-CoV-2, many disinfectant determinations can be compromised by the cytotoxic effect in cell lines for viral growth such that only a higher detection limit of virus is possible. 102 Thus, while the disinfectant may seem efficacious to some extent of the experimentation, lower levels of infectious virus could not be ruled out.

irradiation have been assessed for several CoVs, mostly those which are regarded as potential testing surrogates. Gamma irradiation is known for its ability to penetrate various biomaterials and packaging. Radiation doses of 2-3 Mrads (20-30 kGy) are generally effective to achieve sterility. UV light can be generated in a spectrum of 200-400 nm, but the narrower range of 200-280 nm (UVC) is the more virucidal.

Commercial UV lights often produce approximately 250 nm emission. UV light is absorbed by plastic and glass products and does not penetrate solid substances well.

As far back as 1949, it was known that MHV was susceptible to UV light and that efficacy was time-dependent. 123 In viral culture medium and exposed in a Petri dish, cumulative reduction of 5 logs 10 of MHV quantitation could be achieved. 124 More intense UV exposure reduced MHV load in fifteen minutes. 125 Under different conditions, CCoV could be significantly reduced in fifteen minutes to several days. 125, 126 The latter studies illustrate how the variance in testing methodology can affect the appreciation of efficacy. Other modifications of UV exposure have considerably reduced TGEV titers. 83 For OC43 and 229E, the rapidity of virus reduction was dependent on the contiguous organic load. Virus could be significantly reduced in seconds when exposure was made in the presence of 0.2% bovine serum albumin but required minutes in the presence of 2% fetal calf serum. 127 For 10 6 TCID 50 titres of SARS-CoV, nearly one hour was required to negate the virus in tissue culture medium/plastic wells with UVC at a distance of 80 cm. 79 In a similar setting, SARS-CoV could be inactivated with UVC whereas no effect was achieved with UVA in the same timing of fifteen minutes. 128 Others have found UV exposure to be active against SARS-CoV. 129 For the recycling of N95 respirator masks, UV light was found to be sufficient for SARS-CoV-2 deactivation. 103 UV light provided by a commercial system in combination with riboflavin could considerably reduce SARS-CoV-2 titres in plasma and whole blood under experimental conditions. 130 Overall, UVC exposure is an effective virucidal method, but in the least, it is This article is protected by copyright. All rights reserved.

susceptible to exposure timing, distance from virus load, and burden of organic material in the virus milieu.

Gamma irradiation ( 60 cobalt) had a variable effect on SARS-CoV that was dose-dependent. 128 ,131 Darnell et al. found no effect of gamma irradiation in the range of 3-15 krad. 128 Feldmann et al. found that 2 Mrad was effective. 131 For MERS-CoV, 3 Mrad was deemed effective to decontaminate up to 10 10 pfu/ml. 132 Uniformity for assessing antiviral effects has not been established.

Tests to assess the effect of temperature on viral load lack standardization. In addition, the starting inoculum has been variable (~10 5 -10 7 TCID 50 /ml) as has been the in vitro environment of the virus regarding organic load. Most common, viruses have been assessed in tissue culture medium with various animal serum quantitations.

Efficacy of increasing temperatures can vary for 'dry' heat versus 'wet' heat.

As ambient temperature increases from near 0 o C, CoVs are increasingly labile in a time-dependent fashion. 69 

variable effects at given temperatures. 89, 94, 141 Extremes of humidity can be adverse to CoVs. 70, 141 IBV was susceptible to 56 o C at thirty minutes (5-6 log10 reduction) but required some two hours to be fully inactivated. 142 It was also susceptible to steam when used as a surrogate for a mask decontamination study. 143 Lability for other CoVs at this temperature has been reproduced but again often required up to two hours for complete inactivation. 83, 123, 124, 128, [133] [134] [135] 139, 144, 145 103 There is also progressive loss of SARS-CoV-2 RNA stability with increasing heat treatment; no viral RNA could be detected after either prolonged boiling or autoclaving. 146 Comparative temperature stability studies are few. 127, 133 Both OC43 and SARS-CoV (Betacoronavirus) are less susceptible to temperature inactivation than This article is protected by copyright. All rights reserved.

229E (Alphacoronavirus). Few studies have examined more than one strain of the representative CoVs.

Temperature can have an effect on disinfectant efficacy. 147 For PEDV, efficacy in decontamination was apparent over a temperature range of -20 to 37 o C. 147 Temperature change can also affect the actions of extreme pH. 132, 144 At higher temperatures, both increased acidity or alkalinity garner greater antiviral action.

The impact of bioburden on the efficacy of high temperature inactivation is best shown by the study of Thomas et al. 122 In the extreme bioburden of feces, the survival of PEDV was assessed with animal oral inoculation experiments. Virus could be inactivated in ten minutes at 71 o C and in seven days at room temperature. In lesser circumstances, higher protein or solute concentrations in the virus sample protects viability. 124, 133, 135, 138 Acidity and Alkalinity Acid lability was once a characteristic that was used to help in the classification of viruses. 140 For disinfection, both extremes of hyperacidity and hyperalkalinity can have significant antiviral effects. These effects are time-accrued and vary according to the testing temperatures and virus medium.

For IBV, minimal inactivation was seen at room temperature for thirty minutes over the pH range of 2-9. 142 Over the pH range of 6-8, virus viability was mostly reduced at 37 o C in contrast to 4 or 23 o C. 148 At pH 3 in room temperature for This article is protected by copyright. All rights reserved.

four hours, virus stability was variably reduced. 149 At 4 o C, virus was inactivated at pH 11 but minimally at pH 3. 150 TGEV was minimally affected by pH 5-8 at 4 o C, but pH greater than 7.5 diminished titres at 37 o C. 151 At 37 o C, virus was relatively stable over pH 4-8 and variably inactivated at pH 3. 83, 139, 152 Sodium hydroxide inactivated TGEV. 153 For MHV at 37 o C, virus was inactivated at pH less than 3 and more than 9, but conformational changes in the virus surface proteins were occurring as early as pH 8. 124, 154 CCoV can be inactivated at low and high pH but more so in higher temperature. 126 FCoV was undetectable after exposure to pH >9.7 at 4-25 o C, and virus diminished to a lesser extent with incremental temperature. 155 The application of acidic feed additives (such as citric, fumaric, malic, lactic, phosphoric, formic, propionic, and/or benzoic acids) to porcine diets minimally reduced porcine delta coronavirus survival. 156 229E viability was significantly reduced below pH 5 and above pH 8 at low and high temperatures. 84,120 SAR-CoV was relatively stable over pH 5-9 and for temperatures varying from 4-37 o C, but pH <3 and >12 totally inactivated the virus. 128 SARS-CoV was also susceptible to vinegar. 133 In fecal samples, SARS-CoV could survive for 1-5 days at pH 8-9, but only for several hours at pH 6. 78 Chin et al. find that a pH between 3-10 did not have much effect on SARS-CoV-2 at room temperature for one hour. 102 Salicylic acid can also have some activity against SARS-CoV-2 in a liquid handwash formulation. 113 This article is protected by copyright. All rights reserved.

Strain variation in pH susceptibility has been shown for TGEV and IBV. 142, 149, 152 OC43 was more acid tolerant than 229E. 127 Bleach products are considerably alkaline (undiluted 5% bleach pH~11).

Many other commonly tested and commercially available disinfectants have quite variable pH ranges from 1 to 12. 78, 114, 120, 121 It then begs consideration as to how much the pH plays a role in claimed disinfection versus the direct action of one or more other ingredients in these products. Most commercial products do not post pH values regardless of how much other content descriptions are shown.

Accelerated hydrogen peroxide formulations have been assessed for 229E and PEDV. 121, 157, 158 In full strength exposure with one formulation, greater than 4log 10 reduction in 229E was achieved at 20 o C for one minute in the presence of 5% serum.

Virus-product exposure required Sephadex neutralization. The pH of the product was approximately 3, and surfactants had also been included. 121 For PEDV and with a similar product, 1:16 and 1:32 dilutions have been assessed to inactivate virus. 157, 158 Major reductions in titre have been observed for virus-laden feces. After exposure for 40-60 minutes, pig inoculation bioassays confirmed lack of infectivity.

Hydrogen peroxide vapour automation was highly virucidal against TGEV on stainless steel templates. 159 It was also capable of sterilizing N95 masks for reuse in the context of SARS-CoV-2. 103 Hydrogen peroxide has also been added to ethanol and propanol hand sanitizers that have been internationally subscribed. 160, 161 This article is protected by copyright. All rights reserved.

A different form of oxidizing agent, potassium peroxymonosulfate or oxone, has been mixed with other ingredients which in combination were effective against SARS-CoV and PEDV. 78, 147 Halogens For SARS-CoV, 1:50-1:100 dilution of household bleach (50,000 ppm chlorine equivalent of undiluted) can reduce virus by >3 log 10 in five minutes at room temperature. 78 In other study, the virus was susceptible after exposure for thirty minutes at 20 o C to chlorine solution (from sodium hypochlorite) in a dose and time responsive manner. 80 Others have found 0.1% hypochlorite to be active against SARS-CoV. 129 Chlorine-based solution was more effective than chlorine dioxide.

Chlorine-based solution could negate virus in the context of waste water. 80 When applied to a patient environment, a 1:100 dilution of 5% sodium hypochlorite prevented MERS-CoV detection by genetic amplification. 93 229E was also inactivated with 0.10-0.5% hypochlorite, and some strain variation was noted in one study. 120, 162 MHV was inactivated with 0.21% sodium hypochlorite. 163 Another study with sodium hypochlorite 100 ppm was effective for MHV and CCoV but not when diluted to 10 ppm. 125 In contrast, a 1:100 dilution of 6% sodium hypochlorite minimally inactivated MHV and TGEV on stainless steel carriers. 115 Others found hypochlorite inactivation of TGEV. 153 Chloramine T functions like hypochlorite solutions but is also highly oxidizing. In concentrations of 0.10%, it inactivates 229E. 120 Sodium chlorite (0.23%) was not active against the latter viruses in the same study, but it should be recognized that the action of sodium chlorite is considerably different than that of sodium hypochlorite.

For MERS-CoV and SARS-CoV, povidone-iodine preparations were assessed for antiviral action. 118, 120, 145, 164 In 1:1 dilution of several such preparations, virus activity was lost after two minutes, and some product was effective as early as one minute. 145 Other povidone-iodine preparations were tested in the milieu of bovine serum albumin with or without added red blood cells. 118, 163 Marked virus reductions were found at 15 seconds, and complete inactivation occurred at 30 seconds for 1:30

dilutions. An iodophor was effective against MHV and CCoV in 50 ppm but not 5 ppm. 125 The pH of 10% povidone-iodine in one product was 3. 120 With SARS-CoV-2, 7.5% povidone-iodine was found to inactivate high titres of virus after five minutes. 102 Combination halides (hypochlorite and potassium bromide) in 0.05% solution are alkaline and have activity against 229E. 120 Halogen activity can be augmented by creating working solutions that also have surfactants or have low pH. This article is protected by copyright. All rights reserved.

MERS-CoV, SARS-CoV, MHV, and CCoV are formaldehyde/formalin intolerant, and effective concentrations can be as low as 0.7%. 116, 126, 128, [132] [133] [134] 153 Concentrations as low as 0.009% have antivirus activity but require several days and temperatures at or above room. 126, 128 Paraformaldehyde and ortho-phthalaldehyde are also strongly antiviral. 115, 132, 134 Glutaraldehyde at concentrations as low as 0.7% is also very active and has been assessed with SAR-CoV, 229E, and TGEV. 114,120,133,153 Again, lower concentrations (0.001-0.009%) may require several days and above room temperature. 126 103, [113] [114] [115] 120, 123, 125, 129, 153, 160, 161 In particular, ethanol-based hand rubs have fared well albeit some preparations were enhanced with low levels of hydrogen peroxide. 114, 115, 160, 161 Isopropanol (2-propanol) and n-propanol (1-propanol) have also been active against This article is protected by copyright. All rights reserved.

CoVs when the concentration is over 30%. 98, 125, 133, 160, 161 For MHV, a 79% ethanol mixture with a quaternary ammonium compound was effective over thirty seconds. 164 SARS-CoV-2 infectious virus was reduced on standardized surfaces and suspensions when used alone or with a quaternary ammonium compound. 113 For the aforementioned alcohol products, the effect is time accrued. While there are considerable viral reductions, some assessments do not necessarily find complete inactivation especially when the initial starting point is a high titre. Both ethanol and propanol mixtures can be active in the presence of organic loads. 114 Working dilutions of alcohol-based products have been generally recommended to start at 70% when there is no other active product combined. 111 Methanol in its niche uses is effective against MERS-CoV and SARS-CoV. 132, 145 

It has generally been held that detergents can have antimicrobial activity in addition to their benefit for assisting in the removal of associated organic debris (surfactant activity). For viruses in particular, the ability for detergents to interact with lipids gave the impression that activity should be greater against enveloped viruses in contrast to non-enveloped viruses. There are many potential detergent varieties (cationic, anionic, or neutral). One or more have been compounded with other antimicrobial products in the wide array of commercially-available disinfection This article is protected by copyright. All rights reserved.

products. The studies which have examined these products are quite variable in their description of working dilutions, temperature of use, pH, and contact times.

For TGEV, 0.1% SDS (sodium dodecylsulphate) was highly active after one hour at 37 o C. 83 SDS also appeared to enhance the effect of a phenolic. 120 For CCoV, benzalkonium chloride (BAK) was ineffective, but two other detergents were effective at a 1:100 dilution. 165 BAK (1%) was also ineffective against OC43 in one minute. 119 In yet another format, BAK (0.05%) reduced MHV and CCoV quantitations by 3.7-4.1 log 10 . 125 For SARS-CoV, 1% BAK had antiviral activity but was inferior to sodium hypochlorite. 129 Live titres of SARS-CoV-2 were reduced with 0.1% BAK, but the sensitivity of the assay was compromised by cell line toxicity of the product. 102 Three individual quaternary ammonium compounds showed activity against SARS-CoV-2 either alone or with ethanol at room temperature. 113 Detergent-added complexed solutions were active against for SARS-CoV, MHV, and 229E. 78, 114, 120, 164 Some of the latter solutions have also been of an acidic (pH 3.2) or alkaline nature (pH [8] [9] . 114 An alkaline mixture of quaternary ammonium compounds, surfactants, and glutaraldehyde was inactivated PEDV. 147 It is uncommon to find practical assessments of these agents in the field. One such study found that, despite the regular daily use of a combination of nonionic and anionic surfactants for disinfection, 229E continued to be found by culture from highrisk environmental surfaces in a university classroom. 87 Another study examined the efficacy of cleaning toys with a solution combination of two quaternary ammonium This article is protected by copyright. All rights reserved.

compounds and an alcohol ethoxylate. 166 As assessed with measures of viral RNA presence, CoV presence was not significantly altered, and CoV was much more resilient to the cleaning than most other respiratory viruses so tested.

There are many phenolics which have been used generally in commercial disinfectants. Some of these solutions have had one or more such chemicals with or without other disinfectants added and at variable pH. Generalizing, the effects of phenolics alone have at times underperformed in comparisons to other agents.

Chloroxylenol (0.24%) did not reduce OC43 titres over 10 minutes at 20 o C. 119 229E was not reduced in titre >99.9% when exposed to a three phenolic combination on stainless steel carriers, but the solution could be sufficiently augmented with the addition of either SDS or ethanol. 120 A combination of two phenolics moderately reduced MHV and TGEV titres on steel carriers. 115 Moderate reductions in titres of MHV and CCoV were achieved with Cresol (methyphenol), and the latter underperformed when compared to ethanol. 125 MHV and SARS-CoV were susceptible to chloroxylenol (0.12%) and phenol (2%) respectively. 134, 164 Chloroxylenol (0.05%) was said to be efficacious against SARS-CoV-2, but the lower end of test sensitivity for live virus was compromised by toxicity in cell culture. 102 In other studies, chloroxylenol (0.018-0.094% dilution) showed activity against SARS-CoV-2 at 21-38 o C. 113 Triclosan 0.05%, which has some phenolic properties (a bisphenol), could considerably reduce high titres of MHV. 164 This article is protected by copyright. All rights reserved.

MHV was suspended in murine brain tissue and retained infectivity for mice despite exposure to 1% phenol for four hours at room temperature. 123 In another study, a solution of phenol did not reduce PEDV RNA load in cell culture or in a fecal slurry. 147 

Both OC43 and 229E were not sufficiently inactivated with combinations of cetrimide (containing quaternary ammonium compounds) and chlorhexidine (biguanide), but the addition of 70% ethanol was beneficial. 119,120 Hexamidine did not affect 229E, and chlorhexidine gave mild antiviral activity after prolonged exposure. 116, 117 Chlorhexidine (0.02%) had minimal effect on MHV and CCoV. 125 The assessment of chlorhexidine's action on SARS-CoV-2 was limited by cytotoxicity of the cell line, but virus inactivation was nevertheless noted to reduce high titres. 102 Deoxycholate 0.1%, but not 0.01%, was active against MHV and TGEV. 83, 124 β-propiolactone (0.4%) was active against MHV. Two macrocytic compounds of the calixarene group had little to moderate activity against 229E. 116 A combination of glucoprotamine, surfactant, and a phenolic at pH 9 was weakly active against 229E and SARS-CoV compared to alcohol solutions. 133

There is some jeopardy in translating old studies to the current day. Many name brand disinfectants have changed their formulations over time. Some have listed several different products with nearly the same name albeit with varying ingredients. It may This article is protected by copyright. All rights reserved.

be underappreciated that disinfectants could contain chemicals that are not generally understood to be antiviral. For example, PineSol® may initially be conceived as a 'pine oil' product but yet may simultaneously contain several different surfactants, isopropanol, benzoic acid, glycolic acid, and either acidic or basic pH. 164 As pH variation in itself can have differential antiviral effects, these pH extremes should be considered for products that are promoted for their antiviral properties on the basis of other ingredients. It is therefore important to perform tests with working dilutions rather than with the presumed individual active ingredients.

Given the inherent variability of the aforementioned studies and for whichever antiviral approach, definitive statements for absolute efficacy cannot be made for many products. Nevertheless, the existing science can allow for some cautious applications. The following generalizations should be considered at this time:

A) Studies with surrogate CoVs generally provide good screening prediction for the success of decontamination and disinfection procedures with SARS-CoV, MERS-CoV, and SARS-CoV-2. B) Differences among CoVs have been found for some decontamination and disinfection procedures. It is ultimately the virus of concern that should be exposed under real or experimental conditions to understand the applications in greater relevance. This article is protected by copyright. All rights reserved. I) The immediate environment of patient care should be decluttered for nonessential items since their presence complicates the application of disinfectants.

Just as there are potential perils for efficacy of decontamination or disinfection procedures, there are also safety concerns that can tip the balance when choosing any one or more methods. Among these safety issues are:

A) While concern may be made especially for a CoV with high infectivity and considerable associated clinical morbidity, decontamination and disinfection must also simultaneously consider other pathogens (e.g., bacterial or other) that require eradication in the same context. B) CoV spread in the healthcare and/or patient setting is associated with considerable environmental burden as measured by both live virus and viral RNA. The surface perhaps most disregarded for spread is flooring where virus burden is considerable and where foot traffic is underestimated to play a role. This article is protected by copyright. All rights reserved.

C) Use of any chemical or physical approach must take into consideration the potential for corrosion or disintegration otherwise of the treated material. D) Use of a chemical should consider whether there is likely to be an accumulation that could be harmful to patients or caregivers. E) Use of a chemical should consider whether there are likely to be significant risks of a caustic or flammable nature. In this regard, the use should consider the potential for direct skin contact or for volatility or inhalation. F) Use of a chemical should consider problems that may arise with imposing potential allergens or scents.

Commonly-used disinfectants are often underlabelled for active ingredients, pH, and working dilutions. Preferred temperatures of diluents such as water should also be indicated. SARS-CoV-2-specific data are preferred. It is also preferential to examine decontamination and disinfection protocols in real-life situations of the patient environment. Directed investigative studies have the opportunity to assess the impact of many variables experimentally. Whether studying environmental and fomite viability or aerosol and airborne spread, future assessments should attempt to determine the presence of live and hence infectious virus. Experimental efficacy studies should examine both high and low virus burdens for quantitative reduction but should also consider whether any determinable viable virus is present.

Origin and evolution of pathogenic coronaviruses

Physical interventions to interrupt or reduce the spread of respiratory viruses: systematic review

Hierarchy of susceptibility of viruses to environmental surface disinfectants: a predictor of activity against new and emerging viral pathogens

Improving cleaning of the environment surrounding patients in 36 acute care hospitals

The prevalence, origin, and prevention of six human coronaviruses

Hosts and sources of endemic human coronaviruses

SARS-CoV-2 viral load in upper respiratory specimens of infected patients

Clinical and virological data of the first cases of COVID-19 in Europe: a case series

Long-term SARS coronavirus excretion from patient cohort

Detection of SARS coronavirus in patients with suspected SARS

SARS-associated coronavirus transmission, United States

Epidemiologic features and clinical course of patients with SARS-CoV-2 in

Molecular and serological investigation of 2019-nCoV infected patients: implications of multiple shedding route

Virological assessment of hospitalized patients with COVID-2019

Comparison of different samples for 2019 novel coronavirus detection by nucleic amplification tests

Dynamic viral SARS-CoV-2 RNA shedding in children: preliminary data and clinical consideration of Italian Regional Center

Chronological changes of viral shedding in adult inpatients with COVID-19 in

Surveillance of community-acquired viral infections due to respiratory viruses in Rhone-Alpes (France) during winter 1994 to 1995

The role of human coronavirus in children hospitalized for acute bronchiolitis, acute gastroenteritis, and febrile seizures: a 2-year prospective study

Detection of four human coronaviruses in respiratory infections in children: a one-year study in Colorado

Human (nonsevere acute respiratory syndrome) coronavirus infections in hospitalised children in France

Human coronavirus NL63 in children: epidemiology, disease spectrum, and genetic diversity

Coronavirus infection and hospitalizations for acute respiratory illness in young children

Molecular detection of gastrointestinal viral infections in hospitalized patients

Detection of human coronaviruses in simultaneously collected stool samples and nasopharyngeal swabs from hospitalized children with acute gastroenteritis

Detection of human coronaviruses in children with acute gastroenteritis

Detection of SARS-CoV-2 by RT-PCR in anal from patients who have recovered from coronavirus disease 2019

This article is protected by copyright. All rights reserved

COVID-19 and the digestive system

Prolonged viral shedding in feces of pediatric patients with coronavirus disease 2019

Diarrhea during COVID-19 infection: pathogenesis, epidemiology, prevention and management

Digestive system involvement of novel coronavirus infection: prevention and infection control from a gastroenterology perspective

Features of enteric disease from human coronaviruses: implications for COVID-19

Viral RNA load as determined by cell culture as a management tool for discharge of This article is protected by copyright

Accepted Article SARS-CoV-2 patients from infectious disease wards

Unique epidemiological and clinical features of the emerging 2019 novel coronavirus pneumonia (COVID-19) implicate special control measures

Serial interval of COVID-19 among publicly reported confirmed cases. Emerg Infect Dis

The clinical feature of silent infections of novel coronavirus infection (COVID-19) in Wenzhoud

The enlightenment from two cases of asymptomatic infection with SARS-CoV-2: is it safe after 14 days of isolation?

Rapid asymptomatic transmission of COVID-19 during the incubation period demonstrating strong infectivity in a cluster of youngsters aged 16-23 years outside Wuhan and characteristics of young patients with COVID-19: a prospective contact-tracing study

Epidemiological and clinical features of asymptomatic patients with SARS-CoV-2 infection

Clinical characteristics of 24 asymptomatic infections with COVID-19 screened among close contacts in Nanjing

Preparation for the quarantine of the Diamond Princess cruise ship for COVID-19 in Japan: study design

Clinical features of pediatric patients with coronavirus disease (COVID-19)

Screening of healthcare workers for SARS-CoV-2 highlights the role of asymptomatic carriage in COVID-19 transmission

Evidence supporting transmission of severe acute respiratory syndrome coronavirus 2 while presymptomatic or asymptomatic

Emerg Infect Dis

Estimating the generation interval for coronavirus disease (COVID-19) based on symptoms onset data

SARS-CoV-2 transmission from presymptomatic meeting attendee

Viral dynamics in asymptomatic patients with COVID-19

Characterization of an asymptomatic cohort of SARS-CoV-2 infected individuals outside of Wuhan, China

Secondary transmission of coronavirus disease from presymptomatic persons

Symptomatic infection is associated with prolonged duration of viral shedding in mild coronavirus disease 2019: a retrospective study of 110 children in Wuhan

Prolonged shedding of human coronavirus in hematopoietic cell transplant recipients: risk factors and viral genome evolution

COVID-19 in a patient with long-term use of glucocorticoids: a study of a familial cluster

More data are required for incubation period, infectivity, and quarantine duration for COVID-19

Evidence of airborne transmission of the severe acute respiratory syndrome virus

Transmission of the Severe Acute Respiratory Syndrome on aircraft

Airborne Severe Acute Respiratory Syndrome coronavirus concentrations in a negative-pressure isolation room

Detection of airborne Severe Acute Respiratory Syndrome (SARS) coronavirus and environmental contamination in SARS outbreaks units

Extensive viable Middle East Respiratory Syndrome (MERS) coronavirus contamination in air and surrounding environment in MERS isolation wards

Experimental infection of pigs with the porcine respiratory coronavirus (PRCV): measure of viral excretion

Effects of humidity and other factors on the generation and sampling of a coronavirus aerosol

Evidence of infectivity of airborne porcine epidemic diarrhea virus and detection of airborne viral RNA at long distances from infected herds

Aerosol and surface distribution of Severe Acute Respiratory Syndrome coronavirus 2 in hospital wards

Emerg Infect Dis

Aerosol and surfact stability of SARS-CoV-2 as compared with SARS-CoV-1

Infection and rapid transmission of SARS-CoV-2 in ferrets

Detection of air and surface contamination by SARS-CoV-2 in hospital rooms of infected patients

Environmental contamination by SARS-CoV-2 in a designated hospital for coronavirus disease 2019

Aerodynamic analysis of SARS-CoV-2 in two Wuhan hospitals

Experimental aerosol survival of SARS-CoV-2 in artificial saliva and tissue culture media at medium and high This article is protected by copyright

Surgical mask partition reduces the risk of non-contact transmission in a Golden Syrian hamster model for coronavirus disease 2019 (COVID-19)

Environmental survival and microbicide inactivation of coronaviruses

Modes of transmission of respiratory syncytial virus

Transmission routes of respiratory viruses among humans

Airborne transmission of severe acute respiratory syndrome coronavirus-2 to healthcare workers: a narrative review

Airborne transmission of SARS-CoV-2: the world should face the reality

Airborne or droplet precautions for health workers treating COVID-19?

Survival of severe acute respiratory syndrome coronavirus

Stability of SARS coronavirus in human specimens and environment and its sensitivity to heating and UV irradiation

Study on the resistance of severe acute respiratory syndrome-associated coronavirus

Coronavirus survival on healthcare personal protective equipment

Effects of air temperature and relative humidity on coronavirus survival on surfaces

A cytopathic virus causing a transmissible gastroenteritis in swine

Effect of pH and temperature on the infectivity of human coronavirus 229E

Human coronavirus 229E remains infectious on common touch surface materials

Survival of human coronaviruses 229E and OC43 in suspension and after drying on surfaces: a possible source of hospital-acquired infections

Isolation and identification of human coronavirus 229E from frequently touched environmental surfaces of a university classroom that is cleaned daily

Stability of human metapneumovirus and human coronavirus NL63 on medical instruments and in the patient environment

The effects of temperature and relative humidity on the viability of the SARS coronavirus

Severe acute respiratory syndrome coronavirus on hospital surfaces

Risk factors for SARS infection within hospitals in Hanoi, Vietnam

Stability of Middle East Respiratory Syndrome coronavirus (MERS-CoV) under different environmental conditions

Environmental contamination and viral shedding in MERS patients during MER-CoV outbreak in South Korea

SARS-CoV-2 RNA detection of hospital isolation wards hygiene monitoring during the coronavirus This article is protected by copyright

Accepted Article disease 2019 outbreak in a Chinese hospital

Coronavirus disease 2019 (COVID-2019) infection among health care workers and implications for prevention measures in a tertiary hospital in Wuhan, China

Environmental cleaning is effective for the eradication of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in contaminated hospital rooms: a patient from the Diamond Princess cruise ship

Environmental contamination of SARS-CoV-2 in healthcare premises

Environmental contamination of SARS-CoV-2 during the COVID-19 outbreak in South Korea

Detection of severe acute respiratory syndrome coronavirus 2 RNA on surfaces in This article is protected by copyright

Accepted Article quarantine rooms. Emerg Infect Dis

Stability of SARS-CoV-2 in different environmental conditions

Effectiveness of N95 respirator decontamination and reuse against SARS-CoV-2. Emerg Infect Dis

Survival of surrogate coronaviruses in water

Concentration and detection of SARS coronavirus in sewage from Xiao Tang Shan hospital and the 309 th Hospital of the Chinese People's Liberation Army

Excretion and detection of SARS coronavirus and its nucleic acid from digestive system

SARS-CoV-2 RNA in wastewater anticipated COVID-19 occurrence in a low prevalence area

Deposition of respiratory virus pathogens on frequently touched surfaces at airports

Porcine epidemic diarrhoea virus in Italy: disease spread and the role of transportation

Monitoring survivability and infectivity of porcine epidemic diarrhea virus (PEDV) in the infected on-farm earthen manure storages (EMS)

Ayliffe's: Principles and Practice of Disinfection, Preservation, and Sterilization. Fifth Edition

Promises and pitfalls of recent advances in chemical means of preventing the spread of nosocomial infections by environmental surfaces

Microbicidal actives with virucidal efficacy against SARS-CoV-2

Inactivation of surrogate coronaviruses on hard surfaces by health care germicides

Antiseptic properties of two calix[4]arenes derivatives on the human coronavirus 229E

A new Sephadex TM -based method for removing microbicidal and cytotoxic residues when testing antiseptics against viruses: experiments with a human coronavirus as a model

In vitro bactericidal and virucidal efficacy of povidone-iodine gargle/mouthwash against respiratory and oral tract pathogens

The action of three antiseptics/disinfectants against enveloped and non-enveloped viruses

Chemical disinfection of nonporous inanimate surfaces experimentally contaminated with four human pathogenic viruses

Broad-spectrum microbicidal activity, toxicologic assessment, and materials compatibility of a new generation of accelerated hydrogen peroxide-based environmental surface disinfectant

Evaluation of time and temperature sufficient to inactivate porcine epidemic diarrhea virus in swine feces on metal surfaces

A murine virus (JHM) causing disseminated encephalomyelitis with extensive destruction of myelin

Physico-chemical properties of mouse hepatitis virus (MHV-2) grown on DBT cell culture

Virucidal efficacy of physicochemical treatments against coronaviruses and parvoviruses of laboratory animals

Canine coronavirus inactivation with physical and chemical agents

Studies with human coronaviruses II. Some properties of strains 229E and OC43

Inactivation of the coronavirus that induces severe acute respiratory syndrome, SARS-CoV

SARS-CoV, influenza, and syncytial respiratory virus resistance against common disinfectants and ultraviolet irradiation

Pathogen reduction of SARS-CoV-2 virus in plasma and whole blood using riboflavin and UV light

This article is protected by copyright. All rights reserved

Gamma irradiation as an effective method for inactivation of emerging viral pathogens

Inactivation and safety testing of Middle East Respiratory Syndrome coronavirus

-2):1-6. 134. World Health Organization. First data on stability and resistance of SARS coronavirus compiled by members of WHO laboratory network

Physico-chemical properties of murine hepatitis virus, strain A 59

Thermal inactivation studies of a coronavirus, transmissible gastroenteritis virus

Studies on the survival of canine coronavirus under different environmental conditions

Stability of infectious human coronavirus NL63

Studies on transmissible gastroenteritis of swine II. Selected characteristics of a cytopathogenic virus common to five isolates from transmissible gastroenteritis

Purification and biophysical properties of human coronavirus 229E

Survival characteristics of airborne human coronavirus 229E

Characterization of a new infectious bronchitis virus isolate II. Some chemical and physical properties of Clark 333

Decontamination of face masks with steam for mask reuse in fighting the pandemic COVID-19: experimental supports

This article is protected by copyright. All rights reserved

Heat inactivation of the Middle East Respiratory Syndrome coronavirus

Inactivation of SARS coronavirus by means of povidone-iodine, physical conditions, and chemical reagents

Influence of different inactivation methods on severe acute respiratory syndrome coronavirus 2 RNA copy number

Effects of disinfection on the molecular detection of porcine epidemic diarrhea virus

Effect of pH on the growth and cytopathogenicity of avian infectious bronchitis virus in chick kidney cells

pH stability studies with avian infectious bronchitis virus (coronavirus) strains

Neutralizing antibody complex of infectious bronchitis virus

This article is protected by copyright. All rights reserved

The influence of pH on the growth and stability of transmissible gastroenteritis virus in vitro

In vitro differentiation and pH sensitivity of field and cell culture-attenuated strains of transmissible gastroenteritis virus

Laboratory evaluation of selected disinfectants as virucidal agents against porcine parvovirus, pseudorabies virus, and transmissible gastroenteritis virus

Conformational change of the coronavirus peplomer glycoprotein at pH 8.0 and 37 degrees C correlates with virus aggregation and virus-induced cell fusion

Ammonia disinfectant of hatchery waste for elimination of single-stranded RNA viruses

Feed additives decrease survival of delta coronavirus in nursery pig diets. Porcine Health Manag

Efficacy of an accelerated hydrogen peroxide disinfectant to inactivate porcine This article is protected by copyright

Accepted Article epidemic diarrhea virus in swine feces on metal surfaces

Evaluation of an accelerated hydrogen peroxide disinfectant to inactivate porcine epidemic diarrhea virus in swine feces on aluminum surfaces under freezing conditions

Evaluating the virucidal efficacy of hydrogen peroxide vapour

Inactivation of severe acute respiratory syndrome coronavirus 2 by WHOrecommended hand rub formulations and alcohol. Emerg Infect Dis

Virucidal activity of World Health Organization-recommended formulations against enveloped viruses, including Zika, Ebola, and emerging coronaviruses

Evaluation of the antimicrobial efficacy and skin safety of a novel color additive in combination with chlorine disinfectants

Rapid and effective virucidal activity of povidone-iodine products against Middle East Respiratory Syndrome coronavirus (MERS-CoV) and modified vaccinia virus Ankara (MVA)

The antiviral action of common household disinfectants and antiseptics against murine hepatitis virus, a potential surrogate for SARS coronavirus

Action of disinfectants on canine coronavirus replication in vitro

Effect of cleaning and disinfection of toys on infectious diseases and micro-organisms in daycare nurseries