The World Health Organization (WHO) has admitted that coronavirus may linger in the air in crowded indoor spaces suggesting the possibility of aerosol transmission in crowded and inadequately ventilated spaces over a prolonged period of time.  But it has stressed that more evidence in terms of research was required in that direction.

“We have been talking about the possibility of airborne transmission and aerosol transmission as one of the modes of transmission of COVID-19," Maria Van Kerkhove, technical lead on the COVID-19 pandemic at the WHO, told a news briefing.

In the 10-page brief that explored all possible modes of transmission for SARS-CoV-2, the global health agency admitted that aerosol transmission cannot be ruled out, especially in crowded and poorly ventilated areas. It said that airborne spread “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 WHO further stated that understanding how, when and in what types of settings the SARS-CoV-2 virus spreads between people is critical for developing effective public health and infection prevention measures to break chains of transmission. It noted that that studies evaluating Covid-19 outbreaks in restaurants, choir practices and fitness classes suggested the virus might have been spread in the air.

The WHO said current evidence suggests that COVID-19 transmission occurs primarily through direct, indirect, or close contact with infected individuals through their saliva and respiratory secretions, or through their respiratory droplets expelled when they cough, sneeze, talk or sing.

The global health agency has long dismissed the possibility that the coronavirus spreads through the air except for certain risky medical procedures. The WHO also recognised the importance of asymptomatic people spreading Covid-19.

The UN health body has long downplayed this phenomenon. The WHO has repeatedly said such transmission was rare. “Infected people can transmit the virus both when they have symptoms and when they don’t have symptoms,” the agency said. However, the extent of truly asymptomatic infection still remains unknown, it added.

Earlier, a group of 239 scientists from 32 different countries have published an open letter to the WHO and other health agencies, calling for them to update their information on the coronavirus. The group of scientists argue that the WHO needs to give more weight to the role of the airborne spread of Covid-19.