scholarly journals Mechanistic theory predicts the effects of temperature and humidity on inactivation of SARS-CoV-2 and other enveloped viruses

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Dylan H Morris ◽  
Kwe Claude Yinda ◽  
Amandine Gamble ◽  
Fernando W Rossine ◽  
Qishen Huang ◽  
...  
Keyword(s):  
Mechanistic Model ◽  
Virus Transmission ◽  
Mitigation Strategies ◽  
Transmission Risk ◽  
Mechanistic Study ◽  
Enveloped Viruses ◽  
Temperature And Humidity ◽  
Inert Surface ◽  
Human Coronaviruses ◽  
The Stability

Ambient temperature and humidity strongly affect inactivation rates of enveloped viruses, but a mechanistic, quantitative theory of these effects has been elusive. We measure the stability of SARS-CoV-2 on an inert surface at nine temperature and humidity conditions and develop a mechanistic model to explain and predict how temperature and humidity alter virus inactivation. We find SARS-CoV-2 survives longest at low temperatures and extreme relative humidities (RH); median estimated virus half-life is >24 hours at 10C and 40% RH, but ~1.5 hours at 27C and 65% RH. Our mechanistic model uses fundamental chemistry to explain why inactivation rate increases with increased temperature and shows a U-shaped dependence on RH. The model accurately predicts existing measurements of five different human coronaviruses, suggesting that shared mechanisms may affect stability for many viruses. The results indicate scenarios of high transmission risk, point to mitigation strategies, and advance the mechanistic study of virus transmission.

scholarly journals Mechanistic theory predicts the effects of temperature and humidity on inactivation of SARS-CoV-2 and other enveloped viruses

2020 ◽  
Author(s):  
Dylan H. Morris ◽  
Kwe Claude Yinda ◽  
Amandine Gamble ◽  
Fernando W. Rossine ◽  
Qishen Huang ◽  
...  
Keyword(s):  
Mechanistic Model ◽  
Mitigation Strategies ◽  
Inactivation Rate ◽  
Environmental Stability ◽  
Transmission Risk ◽  
Mechanistic Study ◽  
Virus Inactivation ◽  
Enveloped Viruses ◽  
Transmission Potential ◽  
Temperature And Humidity

AbstractEnvironmental conditions affect virus inactivation rate and transmission potential. Understanding those effects is critical for anticipating and mitigating epidemic spread. Ambient temperature and humidity strongly affect the inactivation rate of enveloped viruses, but a mechanistic, quantitative theory of those effects has been elusive. We measure the stability of the enveloped respiratory virus SARS-CoV-2 on an inert surface at nine temperature and humidity conditions and develop a mechanistic model to explain and predict how temperature and humidity alter virus inactivation. We find SARS-CoV-2 survives longest at low temperatures and extreme relative humidities; median estimated virus half-life is over 24 hours at 10 °C and 40 % RH, but approximately 1.5 hours at 27 °C and 65 % RH. Our mechanistic model uses simple chemistry to explain the increase in virus inactivation rate with increased temperature and the U-shaped dependence of inactivation rate on relative humidity. The model accurately predicts quantitative measurements from existing studies of five different human coronaviruses (including SARS-CoV-2), suggesting that shared mechanisms may determine environmental stability for many enveloped viruses. Our results indicate scenarios of particular transmission risk, point to pandemic mitigation strategies, and open new frontiers in the mechanistic study of virus transmission.

scholarly journals Multiscale model for forecasting Sabin 2 vaccine virus household and community transmission

2021 ◽  
Vol 17 (12) ◽  
pp. e1009690
Author(s):  
Michael Famulare ◽  
Wesley Wong ◽  
Rashidul Haque ◽  
James A. Platts-Mills ◽  
Parimalendu Saha ◽  
...  
Keyword(s):  
Clinical Trial ◽  
Mechanistic Model ◽  
Virus Transmission ◽  
Multiscale Model ◽  
Polio Eradication ◽  
Oral Poliovirus Vaccine ◽  
Vaccine Virus ◽  
Mass Action ◽  
Transmission Risk ◽  
Contact Rates

Since the global withdrawal of Sabin 2 oral poliovirus vaccine (OPV) from routine immunization, the Global Polio Eradication Initiative (GPEI) has reported multiple circulating vaccine-derived poliovirus type 2 (cVDPV2) outbreaks. Here, we generated an agent-based, mechanistic model designed to assess OPV-related vaccine virus transmission risk in populations with heterogeneous immunity, demography, and social mixing patterns. To showcase the utility of our model, we present a simulation of mOPV2-related Sabin 2 transmission in rural Matlab, Bangladesh based on stool samples collected from infants and their household contacts during an mOPV2 clinical trial. Sabin 2 transmission following the mOPV2 clinical trial was replicated by specifying multiple, heterogeneous contact rates based on household and community membership. Once calibrated, the model generated Matlab-specific insights regarding poliovirus transmission following an accidental point importation or mass vaccination event. We also show that assuming homogeneous contact rates (mass action), as is common of poliovirus forecast models, does not accurately represent the clinical trial and risks overestimating forecasted poliovirus outbreak probability. Our study identifies household and community structure as an important source of transmission heterogeneity when assessing OPV-related transmission risk and provides a calibratable framework for expanding these analyses to other populations. Trial Registration: ClinicalTrials.gov This trial is registered with clinicaltrials.gov, NCT02477046.

scholarly journals Human Immunodeficiency Virus Transmission Risk in Analytical Treatment Interruption Studies: Relational Factors and Moral Responsibility

2019 ◽  
Vol 220 (Supplement_1) ◽  
pp. S12-S15 ◽  
Author(s):  
Liza Dawson
Keyword(s):  
Human Immunodeficiency Virus ◽  
Risk Mitigation ◽  
Healthcare Providers ◽  
Virus Transmission ◽  
Treatment Interruption ◽  
Mitigation Strategies ◽  
Transmission Risk ◽  
Analytical Treatment ◽  
Immunodeficiency Virus ◽  
Study Participants

Abstract Analytical treatment interruption (ATI) is becoming common in human immunodeficiency virus (HIV) cure-related research, but its use is controversial. ATI raises concerns about risks of HIV transmission to sexual partners of study participants. Researchers may have difficulty addressing these risks, given that study participants’ private behavior is implicated, the partners are not enrolled in the research, and behavioral HIV risk mitigation strategies usually fall outside the study objectives. This analysis argues that researchers should assume some responsibility for partners’ risks, based on the importance of partner relationships for the study participants themselves, and out of concern for the partners’ welfare. Adding this responsibility is reasonable since the risk is created in part by research procedures, and since concern for third parties is often part of professional standards for healthcare providers. Study participants and their partners also bear some responsibility. Specific recommendations for measures to address risk are discussed.

Treatment of Hemophilia A with a Highly Purified Factor VIII Concentrate Prepared by Anti-FVIIIc Immunoaffinity Chromatography

1992 ◽  
Vol 67 (01) ◽  
pp. 019-027 ◽  
Author(s):  
Joseph E Addiego ◽  
Edward Gomperts ◽  
Liu Shu-Len ◽  
Patricia Bailey ◽  
Suzanne G Courter ◽  
...  
Keyword(s):  
Factor Viii ◽  
Hemophilia A ◽  
Virus Transmission ◽  
Human Albumin ◽  
Immunoaffinity Chromatography ◽  
Exchange Chromatography ◽  
Pharmacokinetic Studies ◽  
Enveloped Viruses ◽  
Clinically Significant ◽  
Detergent Mixture

SummaryTo reduce the risk of pathogenic virus transmission associated with the therapeutic administration of plasma-derived antihemophilic factor (FVIIIc), a process utilizing anti-FVIIIc immunoaffinity chromatography to isolate FVIIIc has been developed. In addition, the starting cryoprecipitate solution has been treated with an organic solvent/detergent mixture to inactivate lipid-enveloped viruses. A final ion exchange chromatography step is used to further remove contaminants, e.g., anti-FVIIIc antibody, potentially leached with FVIIIc during the immunoaffinity step. The purified FVTII is stabilized for lyophili-zation and storage by the addition of human albumin. The monoclonal anti-FVIIIc antibody used in the immunoaffinity step of the process is not detectable in the final preparation. Viral reduction studies performed at specific steps of the process demonstrate that 11 logs of human immunodeficiency virus (HIV) and greater than 4-5 logs of other lipid-enveloped viruses are inactivated within the first 30 s of exposure to the solvent/ detergent mixture and 4-5 logs of various model viruses, e. g. Endomyocarditis virus (EMC), are physically removed during washing of the immunoaffinity column. The lyophilized product is reconstituted using sterile water in a matter of seconds.The pharmacokinetics of Hemofil® M were compared to those obtained using a standard heat-treated concentrate (Hemofil® CT) in five severe factor VIII deficient hemophiliacs in a randomized, cross-over study. No statistically significant differences were observed in mean half life (p >0.6) or median recovery (p = 0.4) between the two preparations. No clinically significant adverse effects were observed in patients receiving either FVIII preparation.In addition, 43 patients at 18 different centers underwent pharmacokinetic studies, with a nominal dose of 50 u/kg FVIIIc Hemofil® M. The mean recovery was 103.6%, and the t 1/2 was 14.6 h. The recovery of FVIII in this group was as expected, providing an increase of assayed FVIII of approximately 2% per unit of FVTII/kg infused.Clinical trials using Hemofil® M have been initiated in 124 hemophilia A patients. The safety and efficacy of Hemofil® M has been established. To date, 0 of 60 patients tested have seroconverted to HIV. None of the previously untreated patients show clinical or laboratory evidence of Non-A, Non-B hepatitis (NANB), with 21 patients remaining negative as far as presence of antibodies to the Hepatitis C virus (a-HCV negative) at least 6 months after the initial infusion. There is no evidence of neoantigenicity, evidenced by seroconversion to murine antibody. An 8.7% (2 of 23) prevalence of anti-FVIIIc inhibitor development has been observed in previously untreated patients with FVIIIc⩽3%, receiving only the monoclonally purified solvent/ detergent treated FVIII concentrate while on study and on poststudy surveillance. All patients demonstrated clinical hemostasis following product use for either on demand bleeding or surgical prophylaxis.

scholarly journals Virus Transmission Risk in Urban Rail Systems: Microscopic Simulation-Based Analysis of Spatio-Temporal Characteristics

2021 ◽  
pp. 036119812110101
Author(s):  
Jiali Zhou ◽  
Haris N. Koutsopoulos
Keyword(s):  
Public Transportation ◽  
Virus Transmission ◽  
Flow Characteristics ◽  
Transportation Systems ◽  
Transmission Risk ◽  
Microscopic Simulation ◽  
Spatial And Temporal Patterns ◽  
Subway System ◽  
Public Transportation Systems ◽  
The Impact

The transmission risk of airborne diseases in public transportation systems is a concern. This paper proposes a modified Wells-Riley model for risk analysis in public transportation systems to capture the passenger flow characteristics, including spatial and temporal patterns, in the number of boarding and alighting passengers, and in number of infectors. The model is used to assess overall risk as a function of origin–destination flows, actual operations, and factors such as mask-wearing and ventilation. The model is integrated with a microscopic simulation model of subway operations (SimMETRO). Using actual data from a subway system, a case study explores the impact of different factors on transmission risk, including mask-wearing, ventilation rates, infectiousness levels of disease, and carrier rates. In general, mask-wearing and ventilation are effective under various demand levels, infectiousness levels, and carrier rates. Mask-wearing is more effective in mitigating risks. Impacts from operations and service frequency are also evaluated, emphasizing the importance of maintaining reliable, frequent operations in lowering transmission risks. Risk spatial patterns are also explored, highlighting locations of higher risk.

scholarly journals Stabilizing electrodeposition in elastic solid electrolytes containing immobilized anions

2016 ◽  
Vol 2 (7) ◽  
pp. e1600320 ◽  
Author(s):  
Mukul D. Tikekar ◽  
Lynden A. Archer ◽  
Donald L. Koch
Keyword(s):  
Elastic Solid ◽  
Present Theory ◽  
Metal Electrode ◽  
Mitigation Strategies ◽  
Factors Affecting ◽  
Wide Range ◽  
Current Densities ◽  
Morphological Instabilities ◽  
The Stability

Ion transport–driven instabilities in electrodeposition of metals that lead to morphological instabilities and dendrites are receiving renewed attention because mitigation strategies are needed for improving rechargeability and safety of lithium batteries. The growth rate of these morphological instabilities can be slowed by immobilizing a fraction of anions within the electrolyte to reduce the electric field at the metal electrode. We analyze the role of elastic deformation of the solid electrolyte with immobilized anions and present theory combining the roles of separator elasticity and modified transport to evaluate the factors affecting the stability of planar deposition over a wide range of current densities. We find that stable electrodeposition can be easily achieved even at relatively high current densities in electrolytes/separators with moderate polymer-like mechanical moduli, provided a small fraction of anions are immobilized in the separator.

scholarly journals Application of Hazard Analysis of Critical Control Points (HACCP) Method to Describe Critical Points in Healthcare Waste Management of Razi Hospital in Ghaemshahr, Iran During COVID-19 Pandemic in 2020

2021 ◽  
Vol 13 (3) ◽  
Author(s):  
Seyedeh Fatemeh Erfaneh Mousavi ◽  
Fathollah Gholami-Borujeni
Keyword(s):  
Waste Management ◽  
Direct Contact ◽  
Hazard Analysis ◽  
Virus Transmission ◽  
Transmission Risk ◽  
Control Points ◽  
Healthcare Waste ◽  
Critical Control Points ◽  
Healthcare Waste Management ◽  
Corrective Actions

Background: During the outbreak of COVID-19 in developing countries such as Iran, the management of healthcare waste has become a very important issue. It is necessary to investigate the risk of virus transmission through direct contact, inhalation, and environmental pollution to reduce transmission risk. The Hazard Analysis of Critical Control Points framework is used to simplify quick responses of waste management for facing the novel infectious disease. Objectives: The aim of this study was to use risk analysis frameworks to describe hazard critical control points (HACCP) and make recommendations and corrective actions for staff who work in healthcare facilities and communities experiencing the COVID-19 outbreak. Methods: In the present descriptive-analytical study, a team of environmental health experts identified the critical control points of healthcare waste produced in Razi Hospital and divided them into three categories and six steps. A tested and verified hazard analysis flow diagram was prepared to determine critical points in different steps of healthcare waste management. Critical control points were identified and analyzed by the team at each step. Recommendations and corrective actions were made for each control point. Results: The production rate significantly increased from 580 to 1,733 kg per day, probably caused by the increased use of disposable waste during the pandemic. Transportation, disinfection, and storage appeared to be associated with an individually high level of transmission risk of COVID-19 virus. Also, direct contact with infectious waste was often associated with a high risk of virus transmission. In the final disposal of healthcare waste, people were exposed to a lower level of risk. Conclusions: Training staff in different wards of the hospital to use proper personal protective equipment (PPE), hand washing, disinfectants, and ventilation could reduce the risk of COVID-19 transmission through healthcare waste. Using the HACCP method for providing recommendations and corrective actions could simplify responses to reduce the transmission risk of COVID-19 during pandemics.

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