COVID-19 transmission: Up in the air

Lancet Respiratory Medicine, 29 Oct 2020

[1] Surface transmission is unlikely to be a major route of transmission, as although SARS-CoV-2 can persist for days on inanimate surfaces, attempts to culture the virus from these surfaces were unsuccessful.

[2] For social distancing to be effective, infective respiratory particles would need to fall to the ground or be in low enough concentrations at 2 m from the source to not cause transmission.

(WHO says 1 meter / CDC and NHS say 2 meters)

[3] Earlier threshold was 5 μm to differentiate between large and small particles, but 100 μm theshold could better differentiate the particles.

[4] Particles that would fall to the ground within 2 m are likely to be 60–100 μm in size.

[5] Pathogens are most commonly found in small particle aerosols (<5 μm), which are airborne and breathable.

[6] Transmission from people > 2 m apart has occurred but in enclosed spaces with poor ventilation, and typically with extended exposure to an infected person of more than 30 min.

[7] CDC says most infections are spread through close contact and that airborne transmission is not the primary route of transmission.

Link: Lancet Respiratory Medicine, 29 Oct 2020
https://www.thelancet.com/journals/lanres/article/PIIS2213-2600(20)30514-2/fulltext