Infectious SARS-CoV-2 Is Emitted in Aerosol Particles

Hawks, Seth A.; Prussin, Aaron J.; Kuchinsky, Sarah C.; Pan, Jin; Marr, Linsey C.; Duggal, Nisha K.

doi:10.1128/mbio.02527-21

Cited by 43 publications

(56 citation statements)

References 35 publications

(39 reference statements)

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“…Susceptible individuals move into the infectious compartment following effective contacts (i.e., contacts of a nature and duration sufficient to permit transmission) with infected individuals. In the context of an airborne virus like SARS-CoV-2 (14-20), effective contact may be conceptualized as “sharing air” with an infective case. Following an infectious period, infectious individuals recover with immunity.…”

Section: Methodsmentioning

confidence: 99%

“…While assortative (like-with-like) mixing (13) is characteristic of many communicable disease systems, and this may be expected to limit interaction between vaccinated and unvaccinated sub-populations to some degree, the normal functioning of society means that complete assortativity is not a phenomenon observed in reality. Furthermore, the dominant airborne mode of spread of SARS-CoV-2 (14-20) means that close-range physical mixing of individuals from vaccinated and unvaccinated groups is not necessary for between-group disease transmission. Historically, behaviors that create health risks for the community as well as individuals have been the subject of public health regulation.…”

Section: Introductionmentioning

confidence: 99%

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Impact of Population Mixing Between a Vaccinated Majority and Unvaccinated Minority on Disease Dynamics: Implications for SARS-CoV-2

Tuite

Amoako

Fisman

2021

Preprint

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BackgroundThe speed of vaccine development has been a singular achievement during the SARS-CoV-2 pandemic. However, anti-vaccination movements and disinformation efforts have resulted in suboptimal uptake of available vaccines. Vaccine opponents often frame their opposition in terms of the rights of the unvaccinated. Our objective was to explore the impact of mixing of vaccinated and unvaccinated populations on risk among vaccinated individuals.MethodsWe constructed a simple Susceptible-Infectious-Recovered (SIR) compartmental model of a respiratory infectious disease with two connected sub-populations: vaccinated individuals and unvaccinated individuals. We simulated a spectrum of patterns of mixing between vaccinated and unvaccinated groups that from random mixing to like-with-like mixing (complete assortativity). We evaluated the dynamics of an epidemic within each subgroup, and in the population as a whole, and also evaluated the contact-frequency-adjusted contribution of unvaccinated individuals to risk among the vaccinated.ResultsAs expected, the relative risk of infection was markedly higher among unvaccinated individuals than among vaccinated individuals. However, the contact-adjusted contribution of unvaccinated individuals to infection risk during the epidemic was disproportionate, with unvaccinated individuals contributing to infection risk among the vaccinated at a rate up to 6.4 times higher than would have been expected based on contact numbers alone in the base case. As assortativity increased, the final attack rate decreased among vaccinated individuals, but the contact-adjusted contribution to risk among vaccinated individuals derived from contact with unvaccinated individuals increased.InterpretationWhile risk associated with avoiding vaccination during a virulent pandemic accrues chiefly to the unvaccinated, the choices of these individuals are likely to impact the health and safety of vaccinated individuals in a manner disproportionate to the fraction of unvaccinated individuals in the population.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Impact of Population Mixing Between a Vaccinated Majority and Unvaccinated Minority on Disease Dynamics: Implications for SARS-CoV-2

Tuite

Amoako

Fisman

2021

Preprint

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“…0.69 pfu) are affected by several variables including the viral strain, the cell line chosen, the performance of the quantitative PCR and, importantly for coronaviruses, the choice of the amplified target within the genome; for, if the inoculum contains infected cells or cellular material, some quantitative RT-PCR assays will provide a very high RNA copies result because they detect not only the genomic RNAs but also the much more abundant nested mRNAs that are a hallmark of coronaviruses and other Nidovirales . In their review of published values, Sender et al [ 16 ] reported a range of 10 3 –10 5 genome copies per TCID 50 ; more recently Hawks et al [ 17 ] measured a ratio of approximately 200 genome copies per pfu.…”

Section: Sars-cov-2 and Some Fundamental Concepts Of Aerobiologymentioning

confidence: 99%

“…Hawks et al [ 17 ] also showed that experimentally infected Syrian hamsters exhaled aerosol-size particles containing viral RNA, at a rate of 700 particles min −1 with 99.9% of the particles in the size fraction less than 10 µm. Air samples were also collected with a condensation sampler to preserve infectivity.…”

Section: Animal Modelsmentioning

confidence: 99%

COVID-19: the case for aerosol transmission

Tellier

2022

Interface Focus.

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The COVID-19 pandemic is the most severe pandemic caused by a respiratory virus since the 1918 influenza pandemic. As is the case with other respiratory viruses, three modes of transmission have been invoked: contact (direct and through fomites), large droplets and aerosols. This narrative review makes the case that aerosol transmission is an important mode for COVID-19, through reviewing studies about bioaerosol physiology, detection of infectious SARS-CoV-2 in exhaled bioaerosols, prolonged SARS-CoV-2 infectivity persistence in aerosols created in the laboratory, detection of SARS-CoV-2 in air samples, investigation of outbreaks with manifest involvement of aerosols, and animal model experiments. SARS-CoV-2 joins influenza A virus as a virus with proven pandemic capacity that can be spread by the aerosol route. This has profound implications for the control of the current pandemic and for future pandemic preparedness.

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“…Coleman and co-workers 31 found SARS-CoV-2 viral RNA in both particles with diameters smaller than and larger than 5 μ m, and found that most of the viral RNA was in droplets with diameters less than 5 μ m. These correspond to diameters after evaporation. Santarpia and co-workers 32 found infectious virus in particles both with diameters < 1 μ m and in the range 1–4 μ m, but not in particles larger than 4.1 μ m. Hawks and co-workers 33 were also able to obtain infectious virus in aerosols smaller than 8 μ m. It should be noted that the study of Hawks and co-workers was of infected hamsters, not humans. Finally, Dabisch and co-workers infected macaques with an aerosol of droplets with median diameter 1.4 μ m. 34 This body of very recent work suggests that aerosol particles of order a micrometer carry most of the virus.…”

Section: Introductionmentioning

confidence: 93%

Modeling the filtration efficiency of a woven fabric: The role of multiple lengthscales

et al. 2022

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During the COVID-19 pandemic, many millions have worn masks made of woven fabric to reduce the risk of transmission of COVID-19. Masks are essentially air filters worn on the face that should filter out as many of the dangerous particles as possible. Here, the dangerous particles are the droplets containing the virus that are exhaled by an infected person. Woven fabric is unlike the material used in standard air filters. Woven fabric consists of fibers twisted together into yarns that are then woven into fabric. There are, therefore, two lengthscales: the diameters of (i) the fiber and (ii) the yarn. Standard air filters have only (i). To understand how woven fabrics filter, we have used confocal microscopy to take three-dimensional images of woven fabric. We then used the image to perform lattice Boltzmann simulations of the air flow through fabric. With this flow field, we calculated the filtration efficiency for particles a micrometer and larger in diameter. In agreement with experimental measurements by others, we found that for particles in this size range, the filtration efficiency is low. For particles with a diameter of 1.5 μm, our estimated efficiency is in the range 2.5%–10%. The low efficiency is due to most of the air flow being channeled through relatively large (tens of micrometers across) inter-yarn pores. So, we conclude that due to the hierarchical structure of woven fabrics, they are expected to filter poorly.

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Infectious SARS-CoV-2 Is Emitted in Aerosol Particles

Abstract: SARS-CoV-2 is a respiratory virus and has been isolated from the air near COVID-19 patients. Here, using a hamster model of infection, we demonstrate that SARS-CoV-2 is emitted in aerosol particles prior to and concurrent with the onset of mild disease.

Cited by 43 publications

References 35 publications

Impact of Population Mixing Between a Vaccinated Majority and Unvaccinated Minority on Disease Dynamics: Implications for SARS-CoV-2

Impact of Population Mixing Between a Vaccinated Majority and Unvaccinated Minority on Disease Dynamics: Implications for SARS-CoV-2

COVID-19: the case for aerosol transmission

Modeling the filtration efficiency of a woven fabric: The role of multiple lengthscales

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