“We have been talking about the possibility of airborne transmission and aerosol transmission as one of the modes of transmission of COVID-19,” said Maria Van Kerkhove, technical lead on the COVID-19 pandemic at the WHO.
The WHO has previously said the virus that causes the COVID-19 respiratory disease spreads primarily through small droplets expelled from the nose and mouth of an infected person that quickly sink to the ground.
But in an open letter to the Geneva-based agency, published on Monday in the Clinical Infectious Diseases journal, 239 scientists in 32 countries outlined evidence that they say shows floating virus particles can infect people who breathe them in.
Because those smaller exhaled particles can linger in the air, the scientists are urging WHO to update its guidance.
In a briefing on Tuesday in Geneva, Benedetta Allegranzi, the WHO’s technical lead for infection prevention and control, said there was evidence emerging of airborne transmission of the coronavirus, but that it was not definitive. She added that the possibility of airborne transmission in public settings – especially in very specific conditions, crowded, closed, poorly ventilated settings that have been described, cannot be ruled out.