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1.
Appl Environ Microbiol ; 86(17)2020 08 18.
Article in English | MEDLINE | ID: covidwho-767717

ABSTRACT

The infection of health care workers during the 2013 to 2016 Ebola outbreak raised concerns about fomite transmission. In the wake of the coronavirus disease 2019 (COVID-19) pandemic, investigations are ongoing to determine the role of fomites in coronavirus transmission as well. The bacteriophage phi 6 has a phospholipid envelope and is commonly used in environmental studies as a surrogate for human enveloped viruses. The persistence of phi 6 was evaluated as a surrogate for Ebola virus (EBOV) and coronaviruses on porous and nonporous hospital surfaces. Phi 6 was suspended in a body fluid simulant and inoculated onto 1-cm2 coupons of steel, plastic, and two fabric curtain types. The coupons were placed at two controlled absolute humidity (AH) levels: a low AH of 3.0 g/m3 and a high AH of 14.4 g/m3 Phi 6 declined at a lower rate on all materials under low-AH conditions, with a decay rate of 0.06-log10 PFU/day to 0.11-log10 PFU/day, than under the higher AH conditions, with a decay rate of 0.65-log10 PFU/h to 1.42-log10 PFU/day. There was a significant difference in decay rates between porous and nonporous surfaces at both low AH (P < 0.0001) and high AH (P < 0.0001). Under these laboratory-simulated conditions, phi 6 was found to be a conservative surrogate for EBOV under low-AH conditions in that it persisted longer than Ebola virus in similar AH conditions. Additionally, some coronaviruses persist longer than phi 6 under similar conditions; therefore, phi 6 may not be a suitable surrogate for coronaviruses.IMPORTANCE Understanding the persistence of enveloped viruses helps inform infection control practices and procedures in health care facilities and community settings. These data convey to public health investigators that enveloped viruses can persist and remain infective on surfaces, thus demonstrating a potential risk for transmission. Under these laboratory-simulated Western indoor hospital conditions, we assessed the suitability of phi 6 as a surrogate for environmental persistence research related to enveloped viruses, including EBOV and coronaviruses.


Subject(s)
Bacteriophage phi 6/isolation & purification , Bacteriophage phi 6/physiology , Coronavirus/physiology , Ebolavirus/physiology , Environmental Microbiology , Fomites/virology , Virus Inactivation , Betacoronavirus/physiology , Coronavirus/isolation & purification , Coronavirus Infections/transmission , Coronavirus Infections/virology , Ebolavirus/isolation & purification , Hemorrhagic Fever, Ebola/transmission , Hemorrhagic Fever, Ebola/virology , Hospitals , Humans , Humidity , Pandemics , Pneumonia, Viral/transmission , Porosity , Temperature
3.
Appl Environ Microbiol ; 86(18)2020 09 01.
Article in English | MEDLINE | ID: covidwho-653155

ABSTRACT

Temperature and relative humidity are major factors determining virus inactivation in the environment. This article reviews inactivation data regarding coronaviruses on surfaces and in liquids from published studies and develops secondary models to predict coronaviruses inactivation as a function of temperature and relative humidity. A total of 102 D values (i.e., the time to obtain a log10 reduction of virus infectivity), including values for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), were collected from 26 published studies. The values obtained from the different coronaviruses and studies were found to be generally consistent. Five different models were fitted to the global data set of D values. The most appropriate model considered temperature and relative humidity. A spreadsheet predicting the inactivation of coronaviruses and the associated uncertainty is presented and can be used to predict virus inactivation for untested temperatures, time points, or any coronavirus strains belonging to Alphacoronavirus and Betacoronavirus genera.IMPORTANCE The prediction of the persistence of SARS-CoV-2 on fomites is essential in investigating the importance of contact transmission. This study collects available information on inactivation kinetics of coronaviruses in both solid and liquid fomites and creates a mathematical model for the impact of temperature and relative humidity on virus persistence. The predictions of the model can support more robust decision-making and could be useful in various public health contexts. A calculator for the natural clearance of SARS-CoV-2 depending on temperature and relative humidity could be a valuable operational tool for public authorities.


Subject(s)
Betacoronavirus/physiology , Coronavirus Infections/virology , Models, Biological , Pneumonia, Viral/virology , Virus Inactivation , Fomites/virology , Humans , Humidity , Pandemics , Public Health , Suspensions , Temperature
5.
mSphere ; 5(4)2020 07 01.
Article in English | MEDLINE | ID: covidwho-625402

ABSTRACT

Coronavirus disease 2019 (COVID-19) was first identified in China in late 2019 and is caused by newly identified severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Previous studies had reported the stability of SARS-CoV-2 in cell culture media and deposited onto surfaces under a limited set of environmental conditions. Here, we broadly investigated the effects of relative humidity, temperature, and droplet size on the stability of SARS-CoV-2 in a simulated clinically relevant matrix dried on nonporous surfaces. The results show that SARS-CoV-2 decayed more rapidly when either humidity or temperature was increased but that droplet volume (1 to 50 µl) and surface type (stainless steel, plastic, or nitrile glove) did not significantly impact decay rate. At room temperature (24°C), virus half-life ranged from 6.3 to 18.6 h depending on the relative humidity but was reduced to 1.0 to 8.9 h when the temperature was increased to 35°C. These findings suggest that a potential for fomite transmission may persist for hours to days in indoor environments and have implications for assessment of the risk posed by surface contamination in indoor environments.IMPORTANCE Mitigating the transmission of SARS-CoV-2 in clinical settings and public spaces is critically important to reduce the number of COVID-19 cases while effective vaccines and therapeutics are under development. SARS-CoV-2 transmission is thought to primarily occur through direct person-to-person transfer of infectious respiratory droplets or through aerosol-generating medical procedures. However, contact with contaminated surfaces may also play a significant role. In this context, understanding the factors contributing to SARS-CoV-2 persistence on surfaces will enable a more accurate estimation of the risk of contact transmission and inform mitigation strategies. To this end, we have developed a simple mathematical model that can be used to estimate virus decay on nonporous surfaces under a range of conditions and which may be utilized operationally to identify indoor environments in which the virus is most persistent.


Subject(s)
Fomites/virology , Humidity , Models, Theoretical , SARS Virus/physiology , Temperature , Virus Inactivation , Air Pollution, Indoor , Coronavirus Infections/prevention & control , Coronavirus Infections/transmission , Coronavirus Infections/virology , Half-Life , Humans , Pandemics/prevention & control , Plastics , Pneumonia, Viral/prevention & control , Pneumonia, Viral/transmission , Pneumonia, Viral/virology , Porosity , Saliva/chemistry , Saliva/virology , Stainless Steel , Surface Properties
6.
Appl Environ Microbiol ; 86(17)2020 08 18.
Article in English | MEDLINE | ID: covidwho-614748

ABSTRACT

The infection of health care workers during the 2013 to 2016 Ebola outbreak raised concerns about fomite transmission. In the wake of the coronavirus disease 2019 (COVID-19) pandemic, investigations are ongoing to determine the role of fomites in coronavirus transmission as well. The bacteriophage phi 6 has a phospholipid envelope and is commonly used in environmental studies as a surrogate for human enveloped viruses. The persistence of phi 6 was evaluated as a surrogate for Ebola virus (EBOV) and coronaviruses on porous and nonporous hospital surfaces. Phi 6 was suspended in a body fluid simulant and inoculated onto 1-cm2 coupons of steel, plastic, and two fabric curtain types. The coupons were placed at two controlled absolute humidity (AH) levels: a low AH of 3.0 g/m3 and a high AH of 14.4 g/m3 Phi 6 declined at a lower rate on all materials under low-AH conditions, with a decay rate of 0.06-log10 PFU/day to 0.11-log10 PFU/day, than under the higher AH conditions, with a decay rate of 0.65-log10 PFU/h to 1.42-log10 PFU/day. There was a significant difference in decay rates between porous and nonporous surfaces at both low AH (P < 0.0001) and high AH (P < 0.0001). Under these laboratory-simulated conditions, phi 6 was found to be a conservative surrogate for EBOV under low-AH conditions in that it persisted longer than Ebola virus in similar AH conditions. Additionally, some coronaviruses persist longer than phi 6 under similar conditions; therefore, phi 6 may not be a suitable surrogate for coronaviruses.IMPORTANCE Understanding the persistence of enveloped viruses helps inform infection control practices and procedures in health care facilities and community settings. These data convey to public health investigators that enveloped viruses can persist and remain infective on surfaces, thus demonstrating a potential risk for transmission. Under these laboratory-simulated Western indoor hospital conditions, we assessed the suitability of phi 6 as a surrogate for environmental persistence research related to enveloped viruses, including EBOV and coronaviruses.


Subject(s)
Bacteriophage phi 6/isolation & purification , Bacteriophage phi 6/physiology , Coronavirus/physiology , Ebolavirus/physiology , Environmental Microbiology , Fomites/virology , Virus Inactivation , Betacoronavirus/physiology , Coronavirus/isolation & purification , Coronavirus Infections/transmission , Coronavirus Infections/virology , Ebolavirus/isolation & purification , Hemorrhagic Fever, Ebola/transmission , Hemorrhagic Fever, Ebola/virology , Hospitals , Humans , Humidity , Pandemics , Pneumonia, Viral/transmission , Porosity , Temperature
7.
Emerg Infect Dis ; 26(9)2020 09.
Article in English | MEDLINE | ID: covidwho-614160

ABSTRACT

We spotted severe acute respiratory syndrome coronavirus 2 on polystyrene plastic, aluminum, and glass for 96 hours with and without bovine serum albumin (3 g/L). We observed a steady infectivity (<1 log10 drop) on plastic, a 3.5 log10 decrease on glass, and a 6 log10 drop on aluminum. The presence of proteins noticeably prolonged infectivity.


Subject(s)
Betacoronavirus/isolation & purification , Coronavirus Infections/transmission , Disease Transmission, Infectious , Fomites/virology , Pneumonia, Viral/transmission , Aluminum/analysis , Coronavirus Infections/virology , Glass/analysis , Humans , Pandemics , Plastics/analysis , Pneumonia, Viral/virology , Time Factors
8.
Clin Microbiol Infect ; 26(8): 1094.e1-1094.e5, 2020 Aug.
Article in English | MEDLINE | ID: covidwho-595003

ABSTRACT

OBJECTIVES: To detect possible severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) RNA contamination of inanimate surfaces in areas at high risk of aerosol formation by patients with coronavirus disease 2019 (COVID-19). METHODS: Sampling was performed in the emergency unit and the sub-intensive care ward. SARS-CoV-2 RNA was extracted from swabbed surfaces and objects and subjected to real-time RT-PCR targeting RNA-dependent RNA polymerase and E genes. Virus isolation from positive samples was attempted in vitro on Vero E6 cells. RESULTS: Twenty-six samples were collected and only two were positive for low-level SARS-CoV-2 RNA, both collected on the external surface of continuous positive airway pressure helmets. All transport media were inoculated onto susceptible cells, but none induced a cytopathic effect on day 7 of culture. CONCLUSIONS: Even though daily contact with inanimate surfaces and patient fomites in contaminated areas may be a medium of infection, our data obtained in real-life conditions suggest that it might be less extensive than hitherto recognized.


Subject(s)
Betacoronavirus/growth & development , Fomites/virology , RNA Replicase/genetics , Viral Envelope Proteins/genetics , Animals , Betacoronavirus/genetics , Chlorocebus aethiops , Equipment Contamination , Humans , Intensive Care Units , Microbial Viability , Reverse Transcriptase Polymerase Chain Reaction , Vero Cells , Viral Proteins/genetics
9.
Emerg Infect Dis ; 26(9)2020 Sep.
Article in English | MEDLINE | ID: covidwho-506041

ABSTRACT

We detected severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA on disposable wooden chopsticks used by 5 consecutive asymptomatic and postsymptomatic patients admitted for isolation and care at our hospital. Although we did not assess virus viability, our findings may suggest potential for transmission through shared eating utensils.


Subject(s)
Betacoronavirus/genetics , Cooking and Eating Utensils , Coronavirus Infections/virology , Fomites/virology , Pneumonia, Viral/virology , RNA, Viral/isolation & purification , Coronavirus Infections/transmission , Hong Kong , Humans , Pandemics , Pneumonia, Viral/transmission , Wood/virology
10.
Emerg Infect Dis ; 26(9)2020 09.
Article in English | MEDLINE | ID: covidwho-306108

ABSTRACT

We investigated severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) environmental contamination in 2 rooms of a quarantine hotel after 2 presymptomatic persons who stayed there were laboratory-confirmed as having coronavirus disease. We detected SARS-CoV-2 RNA on 8 (36%) of 22 surfaces, as well as on the pillow cover, sheet, and duvet cover.


Subject(s)
Bedding and Linens/virology , Betacoronavirus/isolation & purification , Coronavirus Infections/transmission , Fomites/virology , Pneumonia, Viral/transmission , RNA, Viral/isolation & purification , Adult , Betacoronavirus/genetics , China/epidemiology , Coronavirus Infections/prevention & control , Coronavirus Infections/virology , Female , Humans , Male , Middle Aged , Pandemics/prevention & control , Pneumonia, Viral/prevention & control , Pneumonia, Viral/virology , Quarantine
11.
Nature ; 583(7818): 834-838, 2020 07.
Article in English | MEDLINE | ID: covidwho-261141

ABSTRACT

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a novel coronavirus with high nucleotide identity to SARS-CoV and to SARS-related coronaviruses that have been detected in horseshoe bats, has spread across the world and had a global effect on healthcare systems and economies1,2. A suitable small animal model is needed to support the development of vaccines and therapies. Here we report the pathogenesis and transmissibility of SARS-CoV-2 in golden (Syrian) hamsters (Mesocricetus auratus). Immunohistochemistry assay demonstrated the presence of viral antigens in nasal mucosa, bronchial epithelial cells and areas of lung consolidation on days 2 and 5 after inoculation with SARS-CoV-2, followed by rapid viral clearance and pneumocyte hyperplasia at 7 days after inoculation. We also found viral antigens in epithelial cells of the duodenum, and detected viral RNA in faeces. Notably, SARS-CoV-2 was transmitted efficiently from inoculated hamsters to naive hamsters by direct contact and via aerosols. Transmission via fomites in soiled cages was not as efficient. Although viral RNA was continuously detected in the nasal washes of inoculated hamsters for 14 days, the communicable period was short and correlated with the detection of infectious virus but not viral RNA. Inoculated and naturally infected hamsters showed apparent weight loss on days 6-7 post-inoculation or post-contact; all hamsters returned to their original weight within 14 days and developed neutralizing antibodies. Our results suggest that features associated with SARS-CoV-2 infection in golden hamsters resemble those found in humans with mild SARS-CoV-2 infections.


Subject(s)
Betacoronavirus/pathogenicity , Coronavirus Infections/transmission , Coronavirus Infections/virology , Disease Models, Animal , Lung/pathology , Lung/virology , Mesocricetus/virology , Pneumonia, Viral/transmission , Pneumonia, Viral/virology , Aerosols , Alveolar Epithelial Cells/pathology , Alveolar Epithelial Cells/virology , Animals , Antibodies, Neutralizing/immunology , Antibodies, Viral/immunology , Antigens, Viral/immunology , Antigens, Viral/isolation & purification , Antigens, Viral/metabolism , Betacoronavirus/immunology , Betacoronavirus/isolation & purification , Betacoronavirus/metabolism , Bronchi/pathology , Bronchi/virology , Coronavirus Infections/immunology , Duodenum/virology , Fomites/virology , Housing, Animal , Kidney/virology , Male , Mesocricetus/immunology , Nasal Mucosa/virology , Pandemics , Pneumonia, Viral/immunology , RNA, Viral/analysis , Viral Load , Weight Loss
12.
Proc Natl Acad Sci U S A ; 117(22): 11875-11877, 2020 06 02.
Article in English | MEDLINE | ID: covidwho-260636

ABSTRACT

Speech droplets generated by asymptomatic carriers of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are increasingly considered to be a likely mode of disease transmission. Highly sensitive laser light scattering observations have revealed that loud speech can emit thousands of oral fluid droplets per second. In a closed, stagnant air environment, they disappear from the window of view with time constants in the range of 8 to 14 min, which corresponds to droplet nuclei of ca. 4 µm diameter, or 12- to 21-µm droplets prior to dehydration. These observations confirm that there is a substantial probability that normal speaking causes airborne virus transmission in confined environments.


Subject(s)
Air Microbiology , Betacoronavirus/physiology , Coronavirus Infections/transmission , Pneumonia, Viral/transmission , Saliva/virology , Dynamic Light Scattering , Fomites/virology , Humans , Pandemics , Particle Size , SARS Virus , Saliva/chemistry , Speech , Viral Load
14.
Med Hypotheses ; 141: 109781, 2020 Aug.
Article in English | MEDLINE | ID: covidwho-116780

ABSTRACT

The world is facing a pandemic of unseen proportions caused by a corona virus named SARS-CoV-2 with unprecedent worldwide measures being taken to tackle its contagion. Person-to-person transmission is accepted but WHO only considers aerosol transmission when procedures or support treatments that produce aerosol are performed. Transmission mechanisms are not fully understood and there is evidence for an airborne route to be considered, as the virus remains viable in aerosols for at least 3 h and that mask usage was the best intervention to prevent infection. Heating, Ventilation and Air Conditioning Systems (HVAC) are used as a primary infection disease control measure. However, if not correctly used, they may contribute to the transmission/spreading of airborne diseases as proposed in the past for SARS. The authors believe that airborne transmission is possible and that HVAC systems when not adequately used may contribute to the transmission of the virus, as suggested by descriptions from Japan, Germany, and the Diamond Princess Cruise Ship. Previous SARS outbreaks reported at Amoy Gardens, Emergency Rooms and Hotels, also suggested an airborne transmission. Further studies are warranted to confirm our hypotheses but the assumption of such way of transmission would cause a major shift in measures recommended to prevent infection such as the disseminated use of masks and structural changes to hospital and other facilities with HVAC systems.


Subject(s)
Air Microbiology , Betacoronavirus/isolation & purification , Coronavirus Infections/transmission , Environment, Controlled , Pandemics , Pneumonia, Viral/transmission , Ventilation , Aerosols , Air Conditioning/adverse effects , Air Conditioning/instrumentation , Air Conditioning/methods , Air Pollution, Indoor , Coronavirus Infections/prevention & control , Cross Infection/transmission , Equipment Contamination , Equipment Design , Equipment Failure , Fomites/virology , Heating/adverse effects , Heating/instrumentation , Heating/methods , Humans , Legionnaires' Disease/epidemiology , Legionnaires' Disease/transmission , Models, Biological , Pandemics/prevention & control , Pneumonia, Viral/prevention & control , Sanitary Engineering/instrumentation , Severe Acute Respiratory Syndrome/epidemiology , Severe Acute Respiratory Syndrome/transmission , Sewage/virology , Ventilation/instrumentation , Ventilation/methods
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