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SARS-CoV-2 Transmission

SARS-CoV-2 is primarily transmitted through virus-laden droplets of moisture (5-10 microns in diameter) that are released from the nose and mouth of an infected person when they cough, sneeze or exhales. These droplets attach to the respiratory tract mucosa or conjunctiva of another person, usually within a distance of 6 feet. SARS-CoV-2 remains viable in aerosols for at least 3 hours. The estimated median half-life of SARS-CoV-2 in the air is 1.1 hours. The levels of the virus that remain in the air after this interval are not high enough to pose a risk to people who are not in the immediate vicinity of an infected person.

Droplets can also settle on surfaces or fomites and can be transferred to another person upon contact. SARS-CoV-2 remains more stable on plastic and steel than on cardboard or copper. Traces of the virus have been detected on plastic and steel surfaces up to three days after contamination. The estimated half-life of SARS-CoV-2 on plastic was 6.8 hours. SARS-CoV-2 survived on cardboard for up to one day. On copper, the most hostile surface tested, the virus persisted for only four hours.

Transmission may also occur through aerosols, which are particles smaller than 5 microns in diameter. Aerosol transmission is a serious risk during procedures such as intubation, bronchoscopy, suctioning, turning a patient to the prone position, or disconnecting a patient from the ventilator.


Van Doremalen N et al. Aerosol and Surface Stability of SARS-CoV-2 as Compared with SARS-CoV-2. New Engl J Med. Published online March 17, 2020 DOI: 10.1056/NEJMc2004973

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