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1.
STAR Protoc ; 3(2): 101188, 2022 06 17.
Article in English | MEDLINE | ID: covidwho-1747493

ABSTRACT

Transmission via fomites poses a major dissemination route for many human pathogens, particularly because of transfer via fingertips. Here, we present a protocol to investigate direct transfer of infectious agents from fomites to humans via naked fingertips. The protocol is suitable for pathogens requiring highest biosafety levels (e.g., SARS-CoV-2). We used an artificial skin to touch a defined volume of virus suspension and subsequent quantification of infectious entities allows quantitative measurement of transfer efficiency and risk assessment. For complete information on the generation and use of this manuscript, please refer to Todt et al. (2021).


Subject(s)
COVID-19 , Viruses , Fomites , Humans , SARS-CoV-2 , Touch
2.
Appl Environ Microbiol ; 88(7): e0255221, 2022 04 12.
Article in English | MEDLINE | ID: covidwho-1741573

ABSTRACT

The persistence of Phi6 (Φ6) bacteriophage on surfaces commonly encountered in consumer-facing environments was evaluated. Φ6 has been utilized as a surrogate for enveloped viruses, including SARS-CoV-2-the causative agent of COVID-19-due to structural similarities, biosafety level 1 (BSL-1) status, and ease of use. Φ6 persistence on fomites was evaluated by characterizing the impact of the inoculum matrix (artificial saliva, phosphate-buffered saline [PBS], tripartite), inoculum level (low and high), and surface type (nonporous-aluminum, stainless steel, plastic, touchscreen, vinyl; porous-wood). Φ6 was inoculated onto surfaces at low and high inoculum levels for each inoculum matrix and incubated (20.54 ± 0.48°C) for up to 168 h. Φ6 was eluted from the surface and quantified via the double agar overlay assay to determine virus survival over time. For nonporous surfaces inoculated with artificial saliva and PBS, significantly higher D values were observed with high inoculum application according to the 95% confidence intervals. In artificial saliva, D values ranged from 1.00 to 1.35 h at a low inoculum and 4.44 to 7.05 h at a high inoculum across inoculation matrices and surfaces. D values for Φ6, regardless of the inoculum level, were significantly higher in tripartite than in artificial saliva and PBS for nonporous surfaces. In contrast with artificial saliva or PBS, D values in tripartite at low inoculum (D values ranging from 45.8 to 72.8 h) were greater than those at high inoculum (D values ranging from 26.4 to 45.5 h) on nonporous surfaces. This study characterized the impact of the inoculum matrix, inoculum level, and surface type on Φ6 survival on various surfaces relevant to fomite transmission in public settings. IMPORTANCE An important consideration in virus contact transmission is the transfer rate between hands and surfaces, which is driven by several factors, including virus persistence on inanimate surfaces. This research characterized Φ6 persistence on surfaces commonly encountered in public settings based on various factors. The inoculum matrix, which simulates the route of transmission, can impact virus persistence, and three separate matrices were evaluated in this study to determine the impact on Φ6 persistence over time. The number of microorganisms has also been suggested to impact persistence, which was evaluated here to simulate real-world contamination scenarios on six surface types. Results from this study will guide future research utilizing Φ6 or other surrogates for enveloped viruses of public health concern.


Subject(s)
Bacteriophages , COVID-19 , Viruses , Fomites , Humans , SARS-CoV-2 , Saliva, Artificial
3.
Appl Environ Microbiol ; 88(7): e0233821, 2022 04 12.
Article in English | MEDLINE | ID: covidwho-1741572

ABSTRACT

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is mainly transmitted via droplets and aerosols. To evaluate the role of transmission by fomites, SARS-CoV-2-specific data on transfer rates from surfaces to hands and from hands to face are lacking. Here, we generated quantitatively controlled transfer rates for SARS-CoV-2 from food items (lettuce, ham, and vegetarian meat alternative [VMA]) and packaging materials (cardboard and plastic) to gloves using a wet, dry, and frozen viral inoculum and from glove to glove using a wet viral inoculum. For biosafety reasons, the transfer from surfaces to hands and hands to face was simulated by using gloves. The cumulative transfer rate was calculated by using the data from the first transfer experiment, food or packaging material to glove, and combined with the transfer rate obtained from the second transfer experiment from glove to glove. The cumulative transfer rates from lettuce (4.7%) and ham (3.4%) were not significantly different (P > 0.05) but were significantly higher (P < 0.05) than that from VMA ("wet" or "frozen"). The wet cumulative transfer rate from VMA (1.3%) was significantly higher than the cumulative transfer rate from frozen VMA (0.0011%). No transfer from plastic or cardboard was observed with a dry inoculum. The plastic packaging under wet conditions provided the highest cumulative transfer rate (3.0%), while the cumulative transfer from frozen cardboard was very small (0.035%). Overall, the transfer rates determined in this study suggest a minor role of foods or food packaging materials in infection transmission. IMPORTANCE The observation of SARS-CoV-2 RNA in swab samples from frozen fish packages in China, confirmed only once by cell culture, led to the hypothesis that food contaminated with SARS-CoV-2 virus particles could be the source of an outbreak. Epidemiological evidence for fomites as infection source is scarce, but it is important for the food industry to evaluate this infection path with quantitative microbial risk assessment (QMRA), using measured viral transfer rates from surfaces to hands and face. The present study provides transfer data for SARS-CoV-2 from various types of foods and packaging materials using quantitative methods that take uncertainties related to the virus recovery from the different surfaces into consideration. The transfer data from this model system provide important input parameters for QMRA models to assess the risk of SARS-CoV-2 transmission from contaminated food items.


Subject(s)
COVID-19 , SARS-CoV-2 , Animals , Fomites , Humans , Plastics , RNA, Viral
4.
Math Biosci Eng ; 19(4): 3564-3590, 2022 02 07.
Article in English | MEDLINE | ID: covidwho-1703601

ABSTRACT

The use of the SEIR model of compartmentalized population dynamics with an added fomite term is analysed as a means of statistically quantifying the contribution of contaminated fomites to the spread of a viral epidemic. It is shown that for normally expected lifetimes of a virus on fomites, the dynamics of the populations are nearly indistinguishable from the case without fomites. With additional information, such as the change in social contacts following a lockdown, however, it is shown that, under the assumption that the reproduction number for direct infection is proportional to the number of social contacts, the population dynamics may be used to place meaningful statistical constraints on the role of fomites that are not affected by the lockdown. The case of the Spring 2020 UK lockdown in response to COVID-19 is presented as an illustration. An upper limit is found on the transmission rate by contaminated fomites of fewer than 1 in 30 per day per infectious person (95% CL) when social contact information is taken into account. Applied to postal deliveries and food packaging, the upper limit on the contaminated fomite transmission rate corresponds to a probability below 1 in 70 (95% CL) that a contaminated fomite transmits the infection. The method presented here may be helpful for guiding health policy over the contribution of some fomites to the spread of infection in other epidemics until more complete risk assessments based on mechanistic modelling or epidemiological investigations may be completed.


Subject(s)
COVID-19 , Epidemics , COVID-19/epidemiology , Communicable Disease Control , Fomites , Humans , United Kingdom/epidemiology
5.
Indoor Air ; 32(2): e12976, 2022 02.
Article in English | MEDLINE | ID: covidwho-1669148

ABSTRACT

We propose the Transmission of Virus in Carriages (TVC) model, a computational model which simulates the potential exposure to SARS-CoV-2 for passengers traveling in a subway rail system train. This model considers exposure through three different routes: fomites via contact with contaminated surfaces; close-range exposure, which accounts for aerosol and droplet transmission within 2 m of the infectious source; and airborne exposure via small aerosols which does not rely on being within 2 m distance from the infectious source. Simulations are based on typical subway parameters and the aim of the study is to consider the relative effect of environmental and behavioral factors including prevalence of the virus in the population, number of people traveling, ventilation rate, and mask wearing as well as the effect of model assumptions such as emission rates. Results simulate generally low exposures in most of the scenarios considered, especially under low virus prevalence. Social distancing through reduced loading and high mask-wearing adherence is predicted to have a noticeable effect on reducing exposure through all routes. The highest predicted doses happen through close-range exposure, while the fomite route cannot be neglected; exposure through both routes relies on infrequent events involving relatively few individuals. Simulated exposure through the airborne route is more homogeneous across passengers, but is generally lower due to the typically short duration of the trips, mask wearing, and the high ventilation rate within the carriage. The infection risk resulting from exposure is challenging to estimate as it will be influenced by factors such as virus variant and vaccination rates.


Subject(s)
Air Pollution, Indoor , COVID-19 , Railroads , Aerosols , Air Microbiology , COVID-19/transmission , Fomites/virology , Humans , SARS-CoV-2
6.
PLoS One ; 17(1): e0261365, 2022.
Article in English | MEDLINE | ID: covidwho-1643242

ABSTRACT

BACKGROUND: Cleanliness of hospital surfaces helps prevent healthcare-associated infections, but comparative evaluations of various cleaning strategies during COVID-19 pandemic surges and worker shortages are scarce. PURPOSE AND METHODS: To evaluate the effectiveness of daily, enhanced terminal, and contingency-based cleaning strategies in an acute care hospital (ACH) and a long-term care facility (LTCF), using SARS-CoV-2 RT-PCR and adenosine triphosphate (ATP) assays. Daily cleaning involved light dusting and removal of visible debris while a patient is in the room. Enhanced terminal cleaning involved wet moping and surface wiping with disinfectants after a patient is permanently moved out of a room followed by ultraviolet light (UV-C), electrostatic spraying, or room fogging. Contingency-based strategies, performed only at the LTCF, involved cleaning by a commercial environmental remediation company with proprietary chemicals and room fogging. Ambient surface contamination was also assessed randomly, without regard to cleaning times. Near-patient or high-touch stationary and non-stationary environmental surfaces were sampled with pre-moistened swabs in viral transport media. RESULTS: At the ACH, SARS-CoV-2 RNA was detected on 66% of surfaces before cleaning and on 23% of those surfaces immediately after terminal cleaning, for a 65% post-cleaning reduction (p = 0.001). UV-C enhancement resulted in an 83% reduction (p = 0.023), while enhancement with electrostatic bleach application resulted in a 50% reduction (p = 0.010). ATP levels on RNA positive surfaces were not significantly different from those of RNA negative surfaces. LTCF contamination rates differed between the dementia, rehabilitation, and residential units (p = 0.005). 67% of surfaces had RNA after room fogging without terminal-style wiping. Fogging with wiping led to a -11% change in the proportion of positive surfaces. At the LTCF, mean ATP levels were lower after terminal cleaning (p = 0.016). CONCLUSION: Ambient surface contamination varied by type of unit and outbreak conditions, but not facility type. Removal of SARS-CoV-2 RNA varied according to cleaning strategy. IMPLICATIONS: Previous reports have shown time spent cleaning by hospital employed environmental services staff did not correlate with cleaning thoroughness. However, time spent cleaning by a commercial remediation company in this study was associated with cleaning effectiveness. These findings may be useful for optimizing allocation of cleaning resources during staffing shortages.


Subject(s)
COVID-19/prevention & control , Cross Infection/prevention & control , Disinfection/methods , Health Personnel/organization & administration , Infection Control/organization & administration , Long-Term Care/organization & administration , Adenosine Triphosphate/analysis , COVID-19/epidemiology , Cross Infection/epidemiology , Disinfectants , Fomites/virology , Health Facilities , Humans , New York/epidemiology , Patients' Rooms , RNA, Viral/analysis , SARS-CoV-2/genetics , SARS-CoV-2/pathogenicity , SARS-CoV-2/radiation effects , Ultraviolet Rays
8.
J Hazard Mater ; 425: 128051, 2022 03 05.
Article in English | MEDLINE | ID: covidwho-1561920

ABSTRACT

The number of people infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continues to increase worldwide, but despite extensive research, there remains significant uncertainty about the predominant routes of SARS-CoV-2 transmission. We conducted a mechanistic modeling and calculated the exposure dose and infection risk of each passenger in a two-bus COVID-19 outbreak in Hunan province, China. This outbreak originated from a single pre-symptomatic index case. Some human behavioral data related to exposure including boarding and alighting time of some passengers and seating position and mask wearing of all passengers were obtained from the available closed-circuit television images/clips and/or questionnaire survey. Least-squares fitting was performed to explore the effect of effective viral load on transmission risk, and the most likely quanta generation rate was also estimated. This study reveals the leading role of airborne SARS-CoV-2 transmission and negligible role of fomite transmission in a poorly ventilated indoor environment, highlighting the need for more targeted interventions in such environments. The quanta generation rate of the index case differed by a factor of 1.8 on the two buses and transmission occurred in the afternoon of the same day, indicating a time-varying effective viral load within a short period of five hours.


Subject(s)
Air Microbiology , COVID-19 , Fomites/virology , Motor Vehicles , SARS-CoV-2 , COVID-19/transmission , Disease Outbreaks , Humans
9.
Indoor Air ; 32(1): e12968, 2022 Jan.
Article in English | MEDLINE | ID: covidwho-1550827

ABSTRACT

Despite their considerable prevalence, dynamics of hospital-associated COVID-19 are still not well understood. We assessed the nature and extent of air- and surface-borne SARS-CoV-2 contamination in hospitals to identify hazards of viral dispersal and enable more precise targeting of infection prevention and control. PubMed, ScienceDirect, Web of Science, Medrxiv, and Biorxiv were searched for relevant articles until June 1, 2021. In total, 51 observational cross-sectional studies comprising 6258 samples were included. SARS-CoV-2 RNA was detected in one in six air and surface samples throughout the hospital and up to 7.62 m away from the nearest patients. The highest detection rates and viral concentrations were reported from patient areas. The most frequently and heavily contaminated types of surfaces comprised air outlets and hospital floors. Viable virus was recovered from the air and fomites. Among size-fractionated air samples, only fine aerosols contained viable virus. Aerosol-generating procedures significantly increased (ORair  = 2.56 (1.46-4.51); ORsurface  = 1.95 (1.27-2.99)), whereas patient masking significantly decreased air- and surface-borne SARS-CoV-2 contamination (ORair  = 0.41 (0.25-0.70); ORsurface  = 0.45 (0.34-0.61)). The nature and extent of hospital contamination indicate that SARS-CoV-2 is likely dispersed conjointly through several transmission routes, including short- and long-range aerosol, droplet, and fomite transmission.


Subject(s)
Air Pollution, Indoor , COVID-19 , Cross Infection/transmission , Hospitals , Air Microbiology , COVID-19/transmission , Cross-Sectional Studies , Fomites/virology , Humans , Observational Studies as Topic , SARS-CoV-2
11.
Lancet Infect Dis ; 21(5): e112, 2021 05.
Article in English | MEDLINE | ID: covidwho-1510459

Subject(s)
COVID-19 , SARS-CoV-2 , Fomites , Humans , Risk
12.
Appl Environ Microbiol ; 87(22): e0121521, 2021 10 28.
Article in English | MEDLINE | ID: covidwho-1494942

ABSTRACT

Fomites can represent a reservoir for pathogens, which may be subsequently transferred from surfaces to skin. In this study, we aim to understand how different factors (including virus type, surface type, time since last hand wash, and direction of transfer) affect virus transfer rates, defined as the fraction of virus transferred, between fingerpads and fomites. To determine this, 360 transfer events were performed with 20 volunteers using Phi6 (a surrogate for enveloped viruses), MS2 (a surrogate for nonenveloped viruses), and three clean surfaces (stainless steel, painted wood, and plastic). Considering all transfer events (all surfaces and both transfer directions combined), the mean transfer rates of Phi6 and MS2 were 0.17 and 0.26, respectively. Transfer of MS2 was significantly higher than that of Phi6 (P < 0.05). Surface type was a significant factor that affected the transfer rate of Phi6: Phi6 is more easily transferred to and from stainless steel and plastic than to and from painted wood. Direction of transfer was a significant factor affecting MS2 transfer rates: MS2 is more easily transferred from surfaces to fingerpads than from fingerpads to surfaces. Data from these virus transfer events, and subsequent transfer rate distributions, provide information that can be used to refine quantitative microbial risk assessments. This study provides a large-scale data set of transfer events with a surrogate for enveloped viruses, which extends the reach of the study to the role of fomites in the transmission of human enveloped viruses like influenza and SARS-CoV-2. IMPORTANCE This study created a large-scale data set for the transfer of enveloped viruses between skin and surfaces. The data set produced by this study provides information on modeling the distribution of enveloped and nonenveloped virus transfer rates, which can aid in the implementation of risk assessment models in the future. Additionally, enveloped and nonenveloped viruses were applied to experimental surfaces in an equivalent matrix to avoid matrix effects, so results between different viral species can be directly compared without confounding effects of different matrices. Our results indicating how virus type, surface type, time since last hand wash, and direction of transfer affect virus transfer rates can be used in decision-making processes to lower the risk of viral infection from transmission through fomites.


Subject(s)
Fingers/virology , Fomites/virology , Virus Physiological Phenomena , Bacteriophage phi 6/physiology , Bacteriophage phi 6/ultrastructure , Fomites/classification , Hand Hygiene , Humans , Levivirus/physiology , Levivirus/ultrastructure , Viral Envelope/ultrastructure , Virus Diseases/transmission , Virus Diseases/virology , Viruses/ultrastructure
13.
Am J Infect Control ; 50(3): 325-329, 2022 03.
Article in English | MEDLINE | ID: covidwho-1487575

ABSTRACT

BACKGROUND: The COVID-19 pandemic has had an unprecedented impact on global health and the world's economies. Proliferation of virulent and deadly SARS-CoV-2 variants require effective transmission mitigation strategies. Under reasonable environmental conditions, culturable and infectious SARS-CoV-2 can survive on contaminated fomites from hours to months. In the present study we evaluated a surface-anchored polymeric quaternary ammonium antimicrobial to help reduce fomite transmission of SARS-CoV-2 from contaminated surfaces. METHODS: Two studies were performed on antimicrobial pre-treated metal disks in March 2020 by two independent Biosafety Level III (BSL-3) equipped laboratories in April 2020. These facilities were in Belgium (the Rega Medical Research Institute) and Australia (the Peter Doherty Institute) and independently applied quantitative carrier-based methodologies using the authentic SARS-CoV-2 isolates (hCoV-19/Australia/VIC01/2020, hCoV-19/Belgium/GHB-03021/2020). RESULTS: Residual dry tests were independently conducted at both facilities and demonstrated sustained virion destruction (108.23 TCID50/carrier GHB-03021 isolate, and 103.66 TCID50/carrier VIC01 isolate) 1 hour (drying) + 10 minutes after inoculation. Reductions are further supported by degradation of RNA on antimicrobial-treated surfaces using qRT-PCR. CONCLUSIONS: Using a polymeric quaternary ammonium antimicrobial (EPA/PMRA registered) the results independently support a sustained antiviral effect via SARS-CoV-2 virion destruction and viral RNA degradation. This indicates that silane-anchored quaternary ammonium compound (SiQAC-18) treated surfaces could play an important role in mitigating the communicability and fomite transmission of SARS-CoV-2.


Subject(s)
Ammonium Compounds , COVID-19 , Fomites , Humans , Pandemics , SARS-CoV-2
14.
Int J Environ Res Public Health ; 18(21)2021 10 24.
Article in English | MEDLINE | ID: covidwho-1480773

ABSTRACT

Severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) is mainly transmitted through respiratory droplets, aerosols, or direct contact with fomites from an infected subject. It has been reported that SARS-CoV-2 is stable and viable in aerosol up to 16 h in controlled laboratory conditions. However, the aerosolization conditions varied a lot between the studies. In this work, an experimental laboratory model of SARS-CoV-2 aerosolization was established, employing an impinger nebulizer, a cylindrical chamber for aerosol travel, and a SKC biosampler for the collection of particles. The efficiency of the system was assessed based on the molecular determination of the viral load in the nebulizer after the aerosolization and in the aerosol collected at the end of the travel. Moreover, the residual infectivity was tested in vitro on the Vero E6 cell line, through the observation of the cytopathic effect (CPE), and the quantification of the viral load in the supernatants at 7 days post inoculation (dpi). A high RNA viral load was found in the SKC biosampler after aerosolization, indicating that it was possible to transport a high virus titer through the 30-cm chamber with all the dilutions (initial 105, 104, 103 plaque forming unit-PFU/mL). At the 7 dpi, an increment of the RNA viral load was determined for the dilutions 105 and 104 PFU/mL tested, while only the initial 105 PFU/mL resulted in visible CPE. Our findings allowed us to achieve the resilience of SARS-CoV-2 in aerosol form, at a concentration comparable to those reported for clinical samples. This mode of transmission should be considered for the mitigation and preventive measures to counteract SARS-CoV-2 spreading.


Subject(s)
COVID-19 , SARS-CoV-2 , Aerosols , Fomites , Humans , Laboratories
15.
Int J Environ Res Public Health ; 18(21)2021 Oct 20.
Article in English | MEDLINE | ID: covidwho-1480740

ABSTRACT

The COVID-19 outbreak is a global health concern. Understanding the transmission modes of the SARS-CoV-2 virus is key to limit the spread of the pandemic. A lack of knowledge about the possibility of SARS-CoV-2 transmission and infection through contaminated surfaces is noticeable and recent studies have stated conflicting findings. This scoping review aims to understand the risks of contaminations via fomites better. Relevant publications were selected through Google Scholar, Web of Science, PubMed, Embase, Medline, and Cochrane Library, with related keywords. PRISMA-ScR guidelines were followed. Out of the 565 articles found, exclusion criteria were applied, duplicates removed, and a total of 25 articles were finally included in the study. The included documents were assessed by the contamination risk: "low" (37.5%), "high" (16.7%), "plausible" (8.3%), "unlikely" (8.3%) risk, and "insufficient evidence" (29.2%). Research in hospital settings was found as the main setting in the reviewed papers, which precisely indicated the risk of contaminated surfaces. This scoping review underscores the risk of SARS-CoV-2 infection via contaminated surfaces assessed as low in the majority of the reviewed articles. Further evaluation of the risk of the virus transmission by fomites and providing adequate information on its infectivity via contaminated surfaces in real-life conditions is essential.


Subject(s)
COVID-19 , SARS-CoV-2 , Fomites , Hospitals , Humans , Pandemics
16.
Indoor Air ; 32(1): e12938, 2022 Jan.
Article in English | MEDLINE | ID: covidwho-1480133

ABSTRACT

Self-contamination during doffing of personal protective equipment (PPE) is a concern for healthcare workers (HCW) following SARS-CoV-2-positive patient care. Staff may subconsciously become contaminated through improper glove removal; so, quantifying this exposure is critical for safe working procedures. HCW surface contact sequences on a respiratory ward were modeled using a discrete-time Markov chain for: IV-drip care, blood pressure monitoring, and doctors' rounds. Accretion of viral RNA on gloves during care was modeled using a stochastic recurrence relation. In the simulation, the HCW then doffed PPE and contaminated themselves in a fraction of cases based on increasing caseload. A parametric study was conducted to analyze the effect of: (1a) increasing patient numbers on the ward, (1b) the proportion of COVID-19 cases, (2) the length of a shift, and (3) the probability of touching contaminated PPE. The driving factors for the exposure were surface contamination and the number of surface contacts. The results simulate generally low viral exposures in most of the scenarios considered including on 100% COVID-19 positive wards, although this is where the highest self-inoculated dose is likely to occur with median 0.0305 viruses (95% CI =0-0.6 viruses). Dose correlates highly with surface contamination showing that this can be a determining factor for the exposure. The infection risk resulting from the exposure is challenging to estimate, as it will be influenced by the factors such as virus variant and vaccination rates.


Subject(s)
Air Pollution, Indoor , COVID-19 , Fomites , Occupational Exposure , Personal Protective Equipment , Fomites/virology , Gloves, Protective/virology , Hospitals , Humans , Personal Protective Equipment/virology , SARS-CoV-2
17.
Appl Environ Microbiol ; 87(21): e0137121, 2021 10 14.
Article in English | MEDLINE | ID: covidwho-1470497

ABSTRACT

Phage Phi6 is an enveloped virus considered a possible nonpathogenic surrogate for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and other viral pathogens in transmission studies. Larger input amounts of bacteriophage Phi6 are shown to delay and protect the phage from environmental decay, both when the phages are dried in plastic tubes and when they are stored in saline solution at 4°C. In contrast, when bacteriophage Phi6 is placed in LB (Luria-Bertani) growth medium (instead of saline) prior to placement on the plastic surface, the influence of the starting concentration on viral recovery is negligible. Protection is reflected in the phage half-lives at higher concentrations being longer than the half-lives at lower concentrations. Because experiments supporting the possibility of fomite transmission of SARS-CoV-2 and other viruses rely upon the survival of infectious virus following inoculation onto various surfaces, large initial amounts of input virus on a surface may generate artificially inflated survival times compared to realistic lower levels of virus that a subject would normally encounter. This is not only because there are extra half-lives to go through at higher concentrations but also because the half-lives themselves are extended at higher virus concentrations. It is important to design surface drying experiments for pathogens with realistic levels of input virus and to consider the role of the carrier and matrix if the results are to be clinically relevant. IMPORTANCE During the coronavirus disease 2019 (COVID-19) pandemic, much attention has been paid to the environmental decay of SARS-CoV-2 due to the proposed transmission of the virus via fomites. However, published experiments have commenced with inocula with very high virus titers, an experimental design not representative of real-life conditions. The study described here evaluated the impact of the initial virus titer on the environmental decay of an enveloped virus, using a nonpathogenic surrogate for the transmission of SARS-CoV-2, enveloped bacteriophage Phi6. We establish that higher concentrations of virus can protect the virus from environmental decay, depending on conditions. This has important implications for stability studies of SARS-CoV-2 and other viruses. Our results point to a limitation in the fundamental methodology that has been used to attribute fomite transmission for almost all respiratory viruses.


Subject(s)
Bacteriophage phi 6 , Pseudomonas syringae/virology , Culture Media , Desiccation , Fomites/virology , Half-Life , Plastics , SARS-CoV-2 , Saline Solution , Temperature , Virus Inactivation
18.
Trop Biomed ; 38(3): 462-468, 2021 Sep 01.
Article in English | MEDLINE | ID: covidwho-1451067

ABSTRACT

COVID-19 has spread rapidly worldwide. The role of fomites in facilitating onward transmission is plausible. This study aimed to determine the presence of viable virus and its persistence on the surfaces of fomites in wards treating COVID-19 patients in Malaysia. This study was conducted in two stages. First, environmental sampling was performed on random days in the intensive care unit (ICU) and general wards. Then, in the second stage, samples were collected serially on alternate days for 7 days in two selected general wards. In Stage 1, a total of 104 samples were collected from the surfaces of highly touched and used areas by patients and healthcare workers. Only three samples were tested positive for SARS-COV-2. In Stage 2, three surface samples were detected positive, but no persistence of the virus was observed. However, none of the SARS-CoV-2 RNA was viable through tissue culture. Overall, the environmental contamination of SARS-CoV-2 was low in this hospital setting. Hospitals' strict infection control and the compliance of patients with wearing masks may have played a role in these findings, suggesting adherence to those measures to reduce occupational exposure of COVID-19 in hospital settings.


Subject(s)
COVID-19/transmission , Environmental Exposure/statistics & numerical data , Fomites/virology , Infection Control/methods , Equipment Contamination , Hospitals/statistics & numerical data , Humans , Intensive Care Units/statistics & numerical data , Malaysia , Patients' Rooms/statistics & numerical data , SARS-CoV-2/isolation & purification
19.
Cancer Radiother ; 25(6-7): 645-647, 2021 Oct.
Article in French | MEDLINE | ID: covidwho-1439911

ABSTRACT

Paper patient file sharing has clearly been identified as a risk behavior for the COVID-19 virus transmission in radiotherapy units. In order to overcome this, the ONCORAD radiotherapy units worked on total dematerialization of the paper patient file, within 3 weeks. The methodology is based on a quality approch. This work has led to a convincing improvement in the management of risks a priori and a smoother patient care workflow.


Subject(s)
COVID-19/prevention & control , Electronic Health Records , Fomites/virology , Health Records, Personal , Paper , Radiation Oncology , COVID-19/transmission , Humans
20.
BMC Nephrol ; 22(1): 313, 2021 09 16.
Article in English | MEDLINE | ID: covidwho-1413890

ABSTRACT

BACKGROUND: SARS-CoV-2 can remain transiently viable on surfaces. We examined if use of shared chairs in outpatient hemodialysis associates with a risk for indirect patient-to-patient transmission of SARS-CoV-2. METHODS: We used data from adults treated at 2,600 hemodialysis facilities in United States between February 1st and June 8th, 2020. We performed a retrospective case-control study matching each SARS-CoV-2 positive patient (case) to a non-SARS-CoV-2 patient (control) treated in the same dialysis shift. Cases and controls were matched on age, sex, race, facility, shift date, and treatment count. For each case-control pair, we traced backward 14 days to assess possible prior exposure from a 'shedding' SARS-CoV-2 positive patient who sat in the same chair immediately before the case or control. Conditional logistic regression models tested whether chair exposure after a shedding SARS-CoV-2 positive patient conferred a higher risk of SARS-CoV-2 infection to the immediate subsequent patient. RESULTS: Among 170,234 hemodialysis patients, 4,782 (2.8 %) tested positive for SARS-CoV-2 (mean age 64 years, 44 % female). Most facilities (68.5 %) had 0 to 1 positive SARS-CoV-2 patient. We matched 2,379 SARS-CoV-2 positive cases to 2,379 non-SARS-CoV-2 controls; 1.30 % (95 %CI 0.90 %, 1.87 %) of cases and 1.39 % (95 %CI 0.97 %, 1.97 %) of controls were exposed to a chair previously sat in by a shedding SARS-CoV-2 patient. Transmission risk among cases was not significantly different from controls (OR = 0.94; 95 %CI 0.57 to 1.54; p = 0.80). Results remained consistent in adjusted and sensitivity analyses. CONCLUSIONS: The risk of indirect patient-to-patient transmission of SARS-CoV-2 infection from dialysis chairs appears to be low.


Subject(s)
Ambulatory Care Facilities , COVID-19/transmission , Fomites/virology , Interior Design and Furnishings , Outpatients , Renal Dialysis , Virus Shedding , Aged , COVID-19/epidemiology , Case-Control Studies , Environmental Exposure , Female , Humans , Infection Control/methods , Logistic Models , Male , Middle Aged , Models, Theoretical , Retrospective Studies , Risk , SARS-CoV-2 , United States/epidemiology
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