The U.S. Centers for Disease Control and Prevention has warned that Covid-19 could spread through airborne particles that can remain suspended in the air and travel beyond six feet.
The agency previously said the virus mainly spreads from person to person through respiratory droplets when a sick person coughs, sneezes or talks.
The updated guidance, posted on the agency's website on Friday, also recommended that people use air purifiers to reduce airborne germs indoors to avoid the disease from spreading.
Airborne viruses are among the most contagious, and the CDC warned that poorly-ventilated places increase the risk of spreading.
Studies have shown that the new coronavirus could spread through aerosols in the air, and the World Health Organization has said it is monitoring "emerging evidence" of possible airborne transmission.