Nationwide use of face masks could bring the spread of Covid-19 under control if 90% to 95% of the U.S. population wore face coverings, Dr. Anthony Fauci said Wednesday. In an interview with the editor of JAMA, Fauci advocated all Americans wear masks and face coverings as a key way to bring an end to the Covid-19 pandemic, particularly as a measure to reign in the spread of the virus until vaccines are widely available against the disease.