How many particles of COVID-19 you are infected with, the viral load, and for how long they may appear in our breath or fluids, viral shedding, are reasonable measures of how able a person is to transmit the virus to another.
COVID-19 viral load
The researchers collected 205 nasopharyngeal swabs of all patients presenting to the Emergency Department (at NYU) over a week in March, who presented with symptoms consistent with COVID-19.