The Centers for Disease Control and Prevention says SARS-CoV-2, the virus that causes COVID-19, is transmitted from person to person, “most likely” when in close contact, within about 6 feet of one another.
Scientists suspect the transmission is similar to how influenza is spread, with the virus travelling through respiratory droplets when infected people cough, sneeze, talk or breathe.
Although “less likely,” SARS-CoV-2 also can be spread through airborne transmission, meaning through small respiratory particles that linger in the air and can reach those who are further than 6 feet away, the CDC says. The evidence shows such airborne transmissions have occurred in enclosed spaces, without adequate ventilation and have involved exercising, shouting or singing by the infected person, the CDC says. Such transmission occurs after “[p]rolonged exposure to these conditions, typically more than 15 minutes,” according to the CDC.
The virus spreads “more efficiently than influenza but not as efficiently as measles,” which is one of the most contagious viruses and one that is transmitted through airborne particles, the CDC says.
The incubation period, or how long before someone who is infected shows symptoms, is estimated to be around four to five days, but can be as long as 14 days, according to the CDC. There is some evidence that asymptomatic people can transmit the virus to others, although the CDC says there is also “a growing body of evidence [that] suggests fully vaccinated people are less likely to have asymptomatic infection and potentially less likely to transmit SARS-CoV-2 to others.”
It also could be possible for people to contract the disease by touching a contaminated surface and then touching their mouth, nose or even eyes, “but the risk is generally considered to be low,” according to the CDC.