The WHO scientific brief was published after more than 200 experts wrote in an open letter to the World Health Organization about airborne transmission of the virus.
The World Health Organization (WHO) said on Thursday that indoor airborne transmission of the coronavirus may be possible after more than 200 scientists urged them to address it.
The organisation has long said that the primary form of coronavirus transmission comes from respiratory droplets passed through close contact with people who are infected and that the only airborne transmission of the virus was in health care settings during medical procedures that generate aerosols.
They now say that airborne transmission in crowded and poorly ventilated areas "cannot be ruled out".
Some studies have suggested this possibility in primarily "indoor crowded spaces...for example, during choir practice, in restaurants or in fitness classes," WHO said.
That could mean that the virus aerosols can remain infectious in the air over a certain length of time. But other studies refute the presence of viral RNA in the air outside of health settings, WHO said, adding that further studies were needed.
The WHO report came following the publication of an open letter in an academic journal appealing to the medical community to "recognise the potential for airborne transmission" that was supported by 239 experts.
"There is significant potential for inhalation exposure to viruses in microscopic respiratory droplets (microdroplets) at short to medium distances (up to several meters, or room scale), and we are advocating for the use of preventive measures to mitigate this route of airborne transmission," doctors said in the open letter.
"Hand washing and social distancing are appropriate, but in our view, insufficient to provide protection" from the virus, the authors had said.
WHO appoints panel to assess global coronavirus response
In another development from the global health body on Thursday, director-general Tedros Adhanom Ghebreyesus appointed a panel to evaluate the lessons learned from the coronavirus response.
Dr Tedros appointed former New Zealand Prime Minister Helen Clark and former Liberian President and Nobel Peace Prize laureate Ellen Johnson Sirleaf to serve as co-chairs of the panel.
"All of us must look in the mirror – WHO, every Member State, all involved in the response. Everyone," Dr Tedros said in remarks at a member state briefing.
The decision comes days after the United States took steps to formally withdraw from the organisation in the midst of the crisis.