The new coronavirus likely is spreading through the air to some degree, the United States' top infectious disease official said on Friday, one day after the World Health Organization changed its guidance on the ways the virus spreads.

"Still some question about aerosol but likely some degree of aerosol," Anthony Fauci, the head of the United States' National Institute of Allergy and Infectious Diseases, said by video during a panel session at a COVID-19 conference organized by the International AIDS Society.