Environmental Stability of Enveloped Viruses Is Impacted by Initial Volume and Evaporation Kinetics of Droplets

French, Andrea J; Longest, Alexandra K; Pan, Jin; Vikesland, Peter J.; Duggal, Nisha K.; Marr, Linsey C.; Lakdawala, Seema S.

doi:10.1128/mbio.03452-22

Cited by 13 publications

(26 citation statements)

References 32 publications

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“…Similarly, Niazi et al 31,32 showed that rapid evaporation and hence rapid efflorescence stabilizes IAV and human rhinovirus-16 in airborne aerosol particles, suggesting that increased stability is due to a shorter exposure to high salinity. An important role of evaporation dynamics on IAV inactivation in droplets was also proposed by French et al, 23 who observed faster inactivation during the initial evaporation step, while the particle is still liquid, and a slower decay after efflorescence. Likewise, a near-instantaneous 50% loss in SARS-CoV-2 infectivity was observed to be associated with efflorescence, followed by a slower inactivation rate.…”

Section: Introductionmentioning

confidence: 52%

“…In typical indoor environments in temperate climates, RH can be as low as 30% during winter, whereas it is around 50% in summer. 8 The RH, 9–19 the temperature, 20–22 and the initial size and composition of the expiratory particle 23–25 dictate the droplet drying rate and hence the concentration of solutes in the droplets. If the RH is below the efflorescence relative humidity (ERH) of the salts, the salts will effloresce.…”

Section: Introductionmentioning

confidence: 99%

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Salt supersaturation as accelerator of influenza A virus inactivation in 1-μl droplets

Schaub,

Luo,

David

et al. 2023

Preprint

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Influenza A virus (IAV) spreads through airborne particles ranging from sub-micrometer to millimeter-sized droplets. The stability of airborne IAV remains difficult to estimate and depends, among others, on the respiratory matrix composition and the size-dependent drying kinetics. Here, we combine experiments on deposited millimeter-sized saline droplets with a biophysical aerosol model to quantify the effect of NaCl on IAV stability, in the presence and absence of sucrose as organic co-solute. We demonstrate that IAV inactivation in dilute saline droplets after exposure to air at various relative humidities is driven by the increasing NaCl molality during water evaporation, rather than by efflorescence, i.e. the precipitation of salt crystals. For pure aqueous NaCl droplets, we find the inactivation rate constant to depend exponentially on NaCl molality, which enables us to simulate inactivation under both efflorescing and deliquescing conditions. We provide evidence for virion integrity loss as the primary inactivation mechanism. Addition of sucrose attenuates IAV inactivation, which we attribute to two mechanisms: first, sucrose decreases the NaCl molality during the drying phase, and second, at equal NaCl molality, sucrose shields IAV from the inactivating effects of NaCl. These experiments help advance our understanding of IAV stability in expiratory particles and the associated transmission risks.

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Section: Introductionmentioning

confidence: 52%

Section: Introductionmentioning

confidence: 99%

Salt supersaturation as accelerator of influenza A virus inactivation in 1-μl droplets

Schaub,

Luo,

David

et al. 2023

Preprint

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“…A review of the literature yielded no studies providing comprehensive validation of the accuracy of using bacteriophage surrogates to infer the airborne infectivity of human viruses, and in some cases, demonstrated that phi6 had different decay rates than other enveloped viruses. 62…”

Section: ■ Experimental Design In Aerovirologymentioning

confidence: 99%

“…Although some bacteriophages may share similar morphology and structure with respiratory viruses, the mechanisms that cause inactivation may differ. A review of the literature yielded no studies providing comprehensive validation of the accuracy of using bacteriophage surrogates to infer the airborne infectivity of human viruses, and in some cases, demonstrated that phi6 had different decay rates than other enveloped viruses …”

Section: Experimental Design In Aerovirologymentioning

confidence: 99%

Toward Standardized Aerovirology: A Critical Review of Existing Results and Methodologies

Groth,

Niazi,

Oswin

et al. 2024

Environ. Sci. Technol.

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Understanding the airborne survival of viruses is important for public health and epidemiological modeling and potentially to develop mitigation strategies to minimize the transmission of airborne pathogens. Laboratory experiments typically involve investigating the effects of environmental parameters on the viability or infectivity of a target airborne virus. However, conflicting results among studies are common. Herein, the results of 34 aerovirology studies were compared to identify links between environmental and compositional effects on the viability of airborne viruses. While the specific experimental apparatus was not a factor in variability between reported results, it was determined that the experimental procedure was a major factor that contributed to discrepancies in results. The most significant contributor to variability between studies was poorly defined initial viable virus concentration in the aerosol phase, causing many studies to not measure the rapid inactivation, which occurs quickly after particle generation, leading to conflicting results. Consistently, studies that measured their reference airborne viability minutes after aerosolization reported higher viability at subsequent times, which indicates that there is an initial loss of viability which is not captured in these studies. The composition of the particles which carry the viruses was also found to be important in the viability of airborne viruses; however, the mechanisms for this effect are unknown. Temperature was found to be important for aerosol-phase viability, but there is a lack of experiments that directly compare the effects of temperature in the aerosol phase and the bulk phase. There is a need for repeated measurements between different research groups under identical conditions both to assess the degree of variability between studies and also to attempt to better understand already published data. Lack of experimental standardization has hindered the ability to quantify the differences between studies, for which we provide recommendations for future studies. These recommendations are as follows: measuring the reference airborne viability using the "direct method"; use equipment which maximizes time resolution; quantify all losses appropriately; perform, at least, a 5-and 10-min sample, if possible; report clearly the composition of the virus suspension; measure the composition of the gas throughout the experiment. Implementing these recommendations will address the most significant oversights in the existing literature and produce data which can more easily be quantitatively compared.

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“…In terms of number, over 90% of respiratory particles released during talking and coughing are <20 μm. The largest of these is 4 × 10 –6 μL in volume, , many orders of magnitude smaller than the droplets (>5 μL) used to mimic contaminated surfaces in previous studies. − SARS-CoV-2 has been shown to decay faster in smaller droplets compared to larger ones (1 vs 50 μL) under some conditions . Therefore, it is essential to examine the survival of SARS-CoV-2 deposited on masks in aerosolized form.…”

Section: Introductionmentioning

confidence: 99%

Stability of Aerosolized SARS-CoV-2 on Masks and Transfer to Skin

Pan,

Gmati,

Roper

et al. 2023

Environ. Sci. Technol.

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The potential for masks to act as fomites in the transmission of SARS-CoV-2 has been suggested but not demonstrated experimentally or observationally. In this study, we aerosolized a suspension of SARS-CoV-2 in saliva and used a vacuum pump to pull the aerosol through six different types of masks. After 1 h at 28 °C and 80% RH, SARS-CoV-2 infectivity was not detectable on an N95 and surgical mask, was reduced by 0.7 log 10 on a nylon/ spandex mask, and was unchanged on a polyester mask and two different cotton masks when recovered by elution in a buffer. SARS-CoV-2 RNA remained stable for 1 h on all masks. We pressed artificial skin against the contaminated masks and detected the transfer of viral RNA but no infectious virus to the skin. The potential for masks contaminated with SARS-CoV-2 in aerosols to act as fomites appears to be less than indicated by studies involving SARS-CoV-2 in very large droplets.

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Environmental Stability of Enveloped Viruses Is Impacted by Initial Volume and Evaporation Kinetics of Droplets

Cited by 13 publications

References 32 publications

Salt supersaturation as accelerator of influenza A virus inactivation in 1-μl droplets

Salt supersaturation as accelerator of influenza A virus inactivation in 1-μl droplets

Toward Standardized Aerovirology: A Critical Review of Existing Results and Methodologies

Stability of Aerosolized SARS-CoV-2 on Masks and Transfer to Skin

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