SHANGHAI -- China's economic hub Shanghai is conducting a new round of screening using both nucleic acid and antigen testing to contain the latest resurgence in COVID-19 infections, a municipal health official told a press conference on Wednesday.

As of 10 am Wednesday, around 9.1 million residents had undergone nucleic acid testing in many areas of the city including those on the east of the Huangpu River that are under temporary closed-off management, said Wu Qianyu, an official with the Shanghai Municipal Health Commission.

Meanwhile, some 10.87 million residents had taken antigen testing to screen for COVID-19 infections by Wednesday morning.

The megacity with a population of over 24 million on Monday began enforcing temporary closed-off management in two phases to track possible infections and curb the spread of the virus.

Starting from Wednesday, Shanghai will carry out a large-scale disinfection lasting one month in key places, such as office buildings, construction sites, transport vehicles, farm markets and residential communities, according to the press conference.