The World Health Organization (WHO) formally recognized Thursday that the coronavirus can be transmitted indoors by droplets in the air, marking a reversal for the United Nations agency.
The WHO said in a scientific brief that people who spend time in crowded settings with poor ventilation run the risk of being infected by the coronavirus as the droplets circulate throughout the air in indoor gatherings. The admission comes after a crush of criticism from experts pushing the organization to update its description of the virus’s spread to include the possibility of airborne infections.
The WHO now acknowledges that transmissions via aerosols, or tiny air droplets, could have been behind “outbreaks of COVID-19 reported in some closed settings, such as restaurants, nightclubs, places of worship or places of work where people may be shouting, talking, or singing.”
Besides refraining from having close contact with infected people and frequent hand-washing, the agency says people should “avoid crowded places, close-contact settings, and confined and enclosed spaces with poor ventilation.”
The WHO still mostly focuses on spread of the virus by larger droplets that are expelled through coughing, sneezing and singing or from contact with a contaminated surface.
“Respiratory droplet transmission can occur when a person is in close contact (within 1 metre) with an infected person who has respiratory symptoms (e.g. coughing or sneezing) or who is talking or singing; in these circumstances, respiratory droplets that include virus can reach the mouth, nose or eyes of a susceptible person and can result in infection,” the agency writes.
The WHO had previously advised that airborne spread is only common when people, mostly health care workers, were involved in medical procedures that produce aerosols, though mounting evidence has surfaced suggesting that the virus can stay in the air for hours and infect a person when inhaled.