Warning: as with all things COVID-19, the evaluation of this topic is changing in real time. There is increasing evidence that SARS-CoV-2 can be aerosolized in day to day settings. The post below was written at the beginning of April and will be updated soon.
…or rather, there is no evidence right now that infectious SARS-CoV-2 virus is airborne.
That said, healthcare workers work in settings where it might hang in the air for a while. This is one reason why they desperately need appropriate masks and personal protective equipment.
The SARS-CoV-2 virus is mainly transmitted via respiratory droplets, which can be inhaled or picked up from contaminated surfaces. Under certain circumstances droplets can become much smaller and become airborne for a few hours (a process called aerosolization). These aerosols can form via coughing and sneezing during respiratory infection (see these studies of flu and droplet/aerosol size here and here). They can also form in during lab and clinical activities such as centrifugation of samples, or intubating a patient. Coronavirus parts (e.g. RNA) have been found in air expelled by patients simply speaking and breathing. Parts, however, are not virus and no study yet has demonstrated that infectious virus is among aerosolized particles in COVID-19 patients. Influenza virus and RNA, however, have been found patient in cough aerosols.
….so healthcare workers need appropriate masks and other protective equipment. The safest thing for the average person to do is to treat SARS-CoV-2 as if it could hang in the air for a while after and infected person sneezes or coughs or speaks – that is, socially distance to the greatest extent that you can.
This topic has been covered extensively by experts elsewhere, and the understanding of it is evolving. We refer you to expert the WHO, and PHAC (Canada) and encourage you to check these resources on a regular basis as expert opinions may change as more information becomes available.
~JFB and HH April 7, 2020