People wear masks on a street in Hong Kong, Friday, Jan. 24, 2020 to celebrate the Lunar New Year which marks the Year of the Rat in the Chinese zodiac. Cutting off access to entire cities with millions of residents to stop a new virus outbreak is a step few countries other than China would consider, but it is made possible by the ruling Communist Party's extensive social controls and experience fighting the 2002-03 outbreak of SARS. (AP Photo/Kin Cheung)