Although much remains unknown about COVID-19, scientists have established that the coronavirus is highly contagious and transmitted via air. Studies suggest that it primarily spreads when infected people cough, sneeze, or talk—actions that expel respiratory droplets containing particles of coronavirus in combination with mucus or saliva. If these droplets land on or are inhaled by others nearby, they could transmit the coronavirus.
Touching doorknobs, computer screens, or other surfaces on which droplets have landed may also lead to infection. The now-common guidelines for wearing masks and physical distancing—typically, by remaining six feet away from others—reflect these observations.
Questions remain, however, about whether tiny coronavirus particles, of about 0.1 microns in size, can become airborne and travel greater distances.