The United States Centers for Disease Control and Prevention updated guidance on its website to say coronavirus can commonly spread "through respiratory droplets or small particles, such as those in aerosols," which are produced even when a person breathes.
"Airborne viruses, including Covid-19, are among the most contagious and easily spread," the site now says.
Previously, the CDC page said that Covid-19 was thought to spread mainly between people in close contact -- about 6 feet (approximately 1.8 meters) -- and "through respiratory droplets produced when an infected person coughs, sneezes or talks."
Now, the page reads:
"There is growing evidence that droplets and airborne particles can remain suspended in the air and be breathed in by others, and travel distances beyond 6 feet (for example, during choir practice, in restaurants, or in fitness classes). In general, indoor environments without good ventilation increase this risk."