Airborne transmission of viruses, like the virus causing COVID-19, is not well understood, but a good baseline for study is a deeper understanding of how particles travel through the air when people cough. In Physics of Fluids, researchers discuss a simulation they created that examines saliva droplets moving through the air in front of a coughing person. The work shows that with a slight breeze of 4 kph, saliva travels 18 feet in 5 seconds.

Source: Six feet not far enough to stop virus transmission in light winds