TL;DR -- Study out of University of Nebraska indicates “Disease spread through both direct (droplet and person-to-person) as well as indirect contact (contaminated objects and 20 airborne transmission) are indicated, supporting the use of airborne isolation precautions.”

Further information on how the new coronavirus is spread — a study out of the University of Nebraska took viral samples from negative pressure rooms of patients in isolation after testing positive for SARS-CoV-2, including both people requiring hospital care and people with milder symptoms. Samples included air samples and samples from a variety of surfaces within the room and bathroom, including patients’ phones.

They found “…significant environmental contamination in rooms where patients infected with SARS-CoV-2 are housed and cared for, regardless of the degree of symptoms or acuity of illness. Contamination exists in all types of samples: high and low-volume air samples, as well as surface samples including personal items, room surfaces, and toilets.”

Hospitalized patients had a higher percentage of positive samples on the whole, but in the first week of isolation the percentage of positive samples was actually similar for less symptomatic and asymptomatic patients as it was for inpatients.

Of crucial importance, “…the data is suggestive that viral aerosol particles are produced by individuals that have the COVID-19 disease, even in the absence of cough.”

Some samples at >6ft and in the hallway after the samples were taken were also positive. “Taken together these results suggest that virus expelled from infected individuals, including from those who are only mildly ill, may be transported by aerosol processes in their local environment, potentially even in the absence of cough or aerosol generating procedures.” While this information doesn’t directly demonstrate viral transmission in people from an airborne route without someone coughing, it does suggest this type of transmission is possible. Healthcare settings may want to consider stricter precautions to protect workers and other patients.

Added: I also think it’s important to note that this hasn’t been peer reviewed yet, and that the samples did not suggest viral replication. However, that does not mean that this degree of environmental viral load is not infectious — we just don’t know one way or the other yet.