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Review
. 2020 Sep 1;202(5):651-659.
doi: 10.1164/rccm.202004-1263PP.

Coughs and Sneezes: Their Role in Transmission of Respiratory Viral Infections, Including SARS-CoV-2

Rajiv Dhand  1 , Jie Li  2
Affiliations
Review

Coughs and Sneezes: Their Role in Transmission of Respiratory Viral Infections, Including SARS-CoV-2

Rajiv Dhand et al. Am J Respir Crit Care Med. .
No abstract available

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Figures

Figure 1.
Figure 1.
Schematic showing the site of origin and mechanisms of droplet generation from the respiratory tract. Adapted by permission from Reference .
Figure 2.
Figure 2.
Illustration to show various routes of transmission. For contact transmission, an infected person can transfer virus-laden respiratory secretions by (A) direct physical contact or (B) indirectly. If an infected person sneezes or coughs and droplets deposit or if they have the virus on their hands from touching their face or blowing their nose and then touch an object or surface, then that object or surface serves as a repository for the contagion. When another individual touches the same object or surface that has the virus on it and then touches their mouth, nose, or eyes, the virus is transmitted to these mucosal surfaces. The most common mode of spread for respiratory viruses is via (C) respiratory droplet transmission. Virus-laden droplets (generated by coughing, sneezing, or talking) are propelled from an infected person directly onto the mucosal surfaces of a host. Respiratory droplets are larger and generally fall to the ground after traveling short distances. Transmission of infection can also occur indirectly after the infected droplets have deposited if a host touches the contaminated surface and then touches their face. (C) Airborne transmission occurs when virus-laden fine respiratory droplets remain viable in the environment and are inhaled by a susceptible individual. This transmission can occur either directly by inhalation of fine droplets expelled from (C) an infected person or (D) during aerosol-generating procedures on an infected individual. Larger droplets expelled by coughing or sneezing evaporate, and these smaller and drier droplet nuclei containing infective microorganisms (lower panel) remain suspended in air for extended periods. They have the potential to deposit in the lower respiratory tract after they are inhaled. Larger droplet nuclei that settle out from the air can potentially be resuspended after their size decreases from evaporation, in combination with an aerosol-generating activity such as making a bed or while doffing personal protective equipment.
Figure 3.
Figure 3.
Schematic showing mechanisms of deposition of inhaled particles in the lung. On entering the nasal or oral cavity, particles deposit by impaction, turbulent mixing, sedimentation, and Brownian motion depending on their size. Particles >5 μm in aerodynamic diameter are most likely to deposit by impaction in the oropharynx and be swallowed, whereas particles <5 μm have the greatest potential for lung deposition. Particles between 4 and 5 μm deposit primarily in the bronchial/conducting airways, whereas smaller particles remain suspended in the airstream and penetrate to the peripheral airways and alveoli. In the lung periphery, a significant reduction in airflow rate allows particles to deposit predominantly by sedimentation, with gravity causing them to “rain out” and deposit. Most particles between 0.1 and 1 μm diffuse by Brownian motion and deposit when they collide with the airway wall. The longer the residence time in the smaller, peripheral airways, the greater the deposition from sedimentation and Brownian motion processes. Inhaled particles that do not deposit are exhaled. Adapted by permission from Reference .
Figure 4.
Figure 4.
Illustration to show the difference between aerosol “generating” versus aerosol “dispersing” procedures. A shows that a small amount of aerosols generated during normal breathing travel short distances before evaporation. B shows a burst of aerosols generated during procedures that provoke coughing such as suctioning, intubation, or bronchoscopy. In C, administration of therapeutic aerosols by nebulizer, noninvasive ventilation, or use of high-flow nasal cannula could disperse aerosols from the patient as a jet to a greater distance.
See this image and copyright information in PMC

References

    1. Fitzgerald D, Sterling TR, Haas D.Mycobacterium tuberculosis Bennett JE, Dolin R, Blaser MJ.editors. Mandell, Douglas, and Bennett's principles and practice of infectious diseases; 9th ed.Philadelphia: Elsevier; 20202985–3021.
    1. Cole EC, Cook CE. Characterization of infectious aerosols in health care facilities: an aid to effective engineering controls and preventive strategies. Am J Infect Control. 1998;26:453–464. - PMC - PubMed
    1. Duguid JP. The numbers and the sites of origin of the droplets expelled during expiratory activities. Edinburgh Med J. 1945;52:385–401. - PMC - PubMed
    1. Guan WJ, Ni ZY, Hu Y, Liang WH, Ou CQ, He JX, et al. China Medical Treatment Expert Group for Covid-19. Clinical characteristics of coronavirus disease 2019 in China. N Engl J Med. 2020;382:1708–1720. - PMC - PubMed
    1. Chung KF, Pavord ID. Prevalence, pathogenesis, and causes of chronic cough. Lancet. 2008;371:1364–1374. - PubMed