Virus survival in evaporated saliva microdroplets deposited on inanimate surfaces

Fedorenko, Aliza; Grinberg, Maor; Orevi, Tomer; Kashtan, Nadav

doi:10.1101/2020.06.15.152983

Cited by 7 publications

(18 citation statements)

References 53 publications

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“…It was hypothesized that biopolymers in saliva may enhance virion survival. 66 Necessarily, these studies give little information on the interaction of virions and aerosols of comparable, that is, submicron, size. However, based on experimental and simulation studies involving nanoparticles and virions, it is plausible that SARS-CoV-2 virions and nanoaerosols bind to form a loose cluster.…”

Section: Aerosol Dispersion and Depositionmentioning

confidence: 99%

Airborne Transmission of COVID-19: Aerosol Dispersion, Lung Deposition, and Virus-Receptor Interactions

2020

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Coronavirus disease 2019 (COVID-19), due to infection by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is now causing a global pandemic. Aerosol transmission of COVID-19, although plausible, has not been confirmed by the World Health Organization (WHO) as a general transmission route. Considering the rapid spread of SARS-CoV-2, especially nosocomial outbreaks and other superspreading events, there is an urgent need to study the possibility of airborne transmission and its impact on the lung, the primary body organ attacked by the virus. Here, we review the complete pathway of airborne transmission of SARS-CoV-2 from aerosol dispersion in air to subsequent biological uptake after inhalation. In particular, we first review the aerodynamic and colloidal mechanisms by which aerosols disperse and transmit in air and deposit onto surfaces. We then review the fundamental mechanisms that govern regional deposition of micro- and nanoparticles in the lung. Focus is given to biophysical interactions between particles and the pulmonary surfactant film, the initial alveolar-capillary barrier and first-line host defense system against inhaled particles and pathogens. Finally, we summarize the current understanding about the structural dynamics of the SARS-CoV-2 spike protein and its interactions with receptors at the atomistic and molecular scales, primarily as revealed by molecular dynamics simulations. This review provides urgent and multidisciplinary knowledge toward understanding the airborne transmission of SARS-CoV-2 and its health impact on the respiratory system.

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Section: Aerosol Dispersion and Depositionmentioning

confidence: 99%

Airborne Transmission of COVID-19: Aerosol Dispersion, Lung Deposition, and Virus-Receptor Interactions

2020

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“…Another concern on dry saliva is that RH and hydration conditions may or may not suffice for virus survival. The observed virus survival in saliva deposited on surfaces, under a wide range of RH levels, have implications in public health, such as those reported in the case of the COVID-19 pandemic [ 94 ]. Investigation of virus survival in dried saliva is needed to determine the need of sensors that detect dry saliva.…”

Section: Discussion and Future Workmentioning

confidence: 99%

Survey of Saliva Components and Virus Sensors for Prevention of COVID-19 and Infectious Diseases

et al. 2020

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The United States Centers for Disease Control and Prevention considers saliva contact the lead transmission mean of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which causes the coronavirus disease 2019 (COVID-19). Saliva droplets or aerosols expelled by sneezing, coughing, breathing, and talking may carry this virus. People in close distance may be exposed directly to these droplets or indirectly when touching the droplets that fall on surrounding surfaces and ending up contracting COVID-19 after touching the mucosa tissue of their faces. It is of great interest to quickly and effectively detect the presence of SARS-CoV-2 in an environment, but the existing methods only work in laboratory settings, to the best of our knowledge. However, it may be possible to detect the presence of saliva in the environment and proceed with prevention measures. However, detecting saliva itself has not been documented in the literature. On the other hand, many sensors that detect different organic components in saliva to monitor a person’s health and diagnose different diseases, ranging from diabetes to dental health, have been proposed and they may be used to detect the presence of saliva. This paper surveys sensors that detect organic and inorganic components of human saliva. Humidity sensors are also considered in the detection of saliva because a large portion of saliva is water. Moreover, sensors that detect infectious viruses are also included as they may also be embedded into saliva sensors for a confirmation of the presence of the virus. A classification of sensors by their working principles and the substances they detect is presented, including the sensors’ specifications, sample size, and sensitivity. Indications of which sensors are portable and suitable for field application are presented. This paper also discusses future research and challenges that must be resolved to realize practical saliva sensors. Such sensors may help minimize the spread of not only COVID-19 but also other infectious diseases.

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“…Interestingly, identified three regimes of viability in terms of RH for the influenza A virus (IAV) in the medium (e.g., phosphatebuffered saline [PBS] and PBS + proteins). Recent experiments on the enveloped Phi6 (a surrogate of SARS-CoV 2) with natural saliva (Fedorenko et al, 2020) have also been carried out: the more complex composition varies the viability vs. RH curve probably due to the interplay of the proteins with the salts, but the U shape is maintained. However, apart from qualitative observations and empirical evidence, the physics underlying these phenomena is not yet understood, and simple thermodynamics models capable to predict the experimental evidences and to explain the abovementioned regimes are not available so far.…”

Section: Introductionmentioning

confidence: 99%

“…Some survival experiments of SARS-CoV 2 in aerosol and on surfaces have been also conducted in the last months (Biryukov et al, 2020;Chin et al, 2020;Fedorenko et al, 2020;van Doremalen et al, 2020). The review by Aboubakr et al (2020) presents tables of coronaviruses stability in aerosol and on surfaces.…”

Section: Introductionmentioning

confidence: 99%

“…For the non-tested RH near 100%-with negligible evaporation and thus near physiological conditions-the viability is expected to be higher, like the bulk solution and thus the U-shaped curve is restored. The experiments reported in by Fedorenko et al (2020) analyzed the viability of the bacteriophage virus Phi6 (an enveloped virus, surrogate of SARS coronavirus) in three different solutions: pure water, SM buffer-in which the main salt is NaCl-and natural saliva. Glass samples were covered by micro-droplets by spraying (droplet diameters in the range 10-600 µm), incubated at different RHs (23, 43, 57, and 78%), and T a 25°C for 14 h and analyzed via plaque assay.…”

Section: Introductionmentioning

confidence: 99%

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Modeling of Virus Survival Time in Respiratory Droplets on Surfaces: A New Rational Approach for Antivirus Strategies

et al. 2021

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The modeling of the viability decay of viruses in sessile droplets is addressed considering a droplet sitting on a smooth surface characterized by a specific contact angle. To investigate, at prescribed temperature, how surface energy of the material and ambient humidity cooperate to determine the virus viability, we propose a model which involves the minimum number of thermodynamically relevant parameters. In particular, by considering a saline water droplet (one salt) as the simplest approximation of real solutions (medium and natural/artificial saliva), the evaporation is described by a first-order time-dependent nonlinear differential equation properly rearranged to obtain the contact angle evolution as the sole unknown function. The analyses were performed for several contact angles and two typical droplet sizes of interest in real situations by assuming constant ambient temperature and relative humidity in the range 0–100%. The results of the simulations, given in terms of time evolution of salt concentration, vapor pressure, and droplet volume, elucidate some previously not yet well-understood dynamics, demonstrating how three main regimes—directly implicated in nontrivial trends of virus viability and to date only highlighted experimentally—can be recognized as the function of relative humidity. By recalling the concept of cumulative dose of salts (CD), to account for the effect of the exposition of viruses to salt concentration on virus viability, we show how the proposed approach could suggest a chart of a virus fate by predicting its survival time at a given temperature as a function of the relative humidity and contact angle. We found a good agreement with experimental data for various enveloped viruses and predicted in particular for the Phi6 virus, a surrogate of coronavirus, the characteristic U-shaped dependence of viability on relative humidity. Given the generality of the model and once experimental data are available that link the vulnerability of a certain virus, such as SARS-CoV-2, to the concentrations of salts or other substances in terms of CD, it is felt that this approach could be employed for antivirus strategies and protocols for the prediction/reduction of human health risks associated with SARS-CoV-2 and other viruses.

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Virus survival in evaporated saliva microdroplets deposited on inanimate surfaces

Cited by 7 publications

References 53 publications

Airborne Transmission of COVID-19: Aerosol Dispersion, Lung Deposition, and Virus-Receptor Interactions

Airborne Transmission of COVID-19: Aerosol Dispersion, Lung Deposition, and Virus-Receptor Interactions

Survey of Saliva Components and Virus Sensors for Prevention of COVID-19 and Infectious Diseases

Modeling of Virus Survival Time in Respiratory Droplets on Surfaces: A New Rational Approach for Antivirus Strategies

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