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Latest "Scientific Brief: SARS-CoV-2 Transmission" by CDC
Updated May 7, 2021
(A thread)
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Updated May 7, 2021
(A thread)
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SARS-CoV-2 is transmitted by exposure to infectious respiratory fluids -
The principal mode by which people are infected with SARS-CoV-2 is through exposure to respiratory fluids carrying infectious virus.
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The principal mode by which people are infected with SARS-CoV-2 is through exposure to respiratory fluids carrying infectious virus.
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Exposure occurs in three principal ways:
1) inhalation of very fine respiratory droplets and aerosol particles,
2) deposition of respiratory droplets and particles on exposed mucous membranes in the mouth, nose, or eye by direct splashes and sprays,
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1) inhalation of very fine respiratory droplets and aerosol particles,
2) deposition of respiratory droplets and particles on exposed mucous membranes in the mouth, nose, or eye by direct splashes and sprays,
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3) touching mucous membranes with hands that have been soiled either directly by virus-containing respiratory fluids or indirectly by touching surfaces with virus on them.
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**Transmission of SARS-CoV-2 from inhalation of virus in the air farther than six feet from an infectious source can occur.**
These transmission events have involved the presence of an infectious person exhaling virus indoors for an extended time (>15 mins & in some cases hours)
These transmission events have involved the presence of an infectious person exhaling virus indoors for an extended time (>15 mins & in some cases hours)
Leading to virus concentrations in the air space sufficient to transmit infections to people more than 6 feet away, and in some cases to people who have passed through that space soon after the infectious person left.
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Factors that 
the risk of infection include:
1) Enclosed spaces with inadequate ventilation or air handling within which the concentration of exhaled respiratory fluids, especially very fine droplets and aerosol particles, can build-up in the air space.
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the risk of infection include:1) Enclosed spaces with inadequate ventilation or air handling within which the concentration of exhaled respiratory fluids, especially very fine droplets and aerosol particles, can build-up in the air space.
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2) Increased exhalation of respiratory fluids if the infectious person is engaged in physical exertion or raises their voice (e.g., exercising, shouting, singing).
3) Prolonged exposure to these conditions, typically more than 15 minutes.
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3) Prolonged exposure to these conditions, typically more than 15 minutes.
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PREVENTION :
The available evidence continues to demonstrate that existing recommendations to prevent SARS-CoV-2 transmission remain effective.
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The available evidence continues to demonstrate that existing recommendations to prevent SARS-CoV-2 transmission remain effective.
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These include :
1) "physical distancing",
2) "community use of well-fitting masks" (e.g., barrier face coverings, procedure/surgical masks), 3) "adequate ventilation", and
4) "avoidance of crowded indoor spaces".
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1) "physical distancing",
2) "community use of well-fitting masks" (e.g., barrier face coverings, procedure/surgical masks), 3) "adequate ventilation", and
4) "avoidance of crowded indoor spaces".
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These methods will reduce transmission both from inhalation of virus and deposition of virus on exposed mucous membranes.
Transmission through soiled hands and surfaces can be prevented by practicing good hand hygiene and by environmental cleaning.
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Transmission through soiled hands and surfaces can be prevented by practicing good hand hygiene and by environmental cleaning.
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