Zhang Wenhong: The Unprecedented Omicron Challenge That Hit Shanghai

Omicron is posing the greatest challenge yet in China’s ever-changing pandemic situation. With a reproduction number (R0) estimated to be as high as 9.5, one person infected with Omicron can spread the infection to 9.5 persons. Such rapid spread is even faster than chicken pox. And such a fast-spreading virus is difficult to control, forcing the introduction of stricter testing and tracking across China, and even lockdowns in some regions, in order to achieve the goal of “zero-Covid.”