World Health Organization says coronavirus airborne transmission is possible indoors

This picture taken on May 12, 2020, shows a sign of the World Health Organization (WHO) in Geneva next to their headquarters. (FABRICE COFFRINI/AFP via Getty Images)

Aerosols containing the COVID-19 virus suspended in the air can infect others upon inhalation in crowded, indoor spaces with poor ventilation, the World Health Organization wrote in an update published late Thursday.

While the WHO previously said airborne transmission is possible during medical procedures generating aerosols, the new message highlights the risk in other indoor areas with close settings and poor ventilation, such as choir practice, restaurants and fitness classes.

"In these events, short-range aerosol transmission, particularly in specific indoor locations, such as crowded and inadequately ventilated spaces over a prolonged period of time with infected persons cannot be ruled out," the organization wrote in the update.

"More studies are urgently needed to investigate such instances and assess their significance for transmission of COVID-19," the WHO added.

The expanded guidelines come after 239 experts wrote an open letter to the organization, urging it to greater acknowledge the risk of COVID-19 airborne transmission.

WHO’s stance also recognized the importance of people spreading COVID-19 without symptoms, a phenomenon the organization has long downplayed.

Fox News has reached out to Johns Hopkins University, the Cleveland Clinic and other health experts for comment on this matter.