The World Health Organisation has acknowledged evidence that coronavirus can be spread by tiny particles suspended in the air.
An official says airborne transmission can't be ruled out in crowded, closed or poorly ventilated settings.
If the evidence is confirmed, it may affect guidelines for indoor spaces.
There are now more than 11 million cases and 500,000 deaths linked to Covid-19 globally.
Dr Mike Ryan, executive director of the WHO, fears there could be a sharp increase in coronavirus fatalities in the coming weeks:
