Shanghai is currently at the most difficult and critical phase in the epidemic control of the current COVID-19 outbreak as the city reported a record high of daily new infections on Saturday, officials said on Sunday.

The city recorded 17 confirmed cases and 492 asymptomatic infections on Saturday, said the municipal health commission.

Six confirmed cases were developed from previously asymptomatic infections. Nine other new confirmed cases and 232 asymptomatic infections were close contacts of the previous infections, and the others were found through screening of people with risk of contracting the virus.

As of the end of Saturday, the current wave of COVID-19 local cases since the beginning of this month has resulted in more than 2,300 infections in the city, including 185 confirmed cases.

"We must take epidemic prevention as the top priority at present, upholding the interest of the people and protecting lives, and making city-wide effort together," said Li Qiang, Party secretary of Shanghai, addressing the city's epidemic prevention and control work leadership group as the leader on Saturday.

The leadership group said that data analysis must play its role in assist making scientific decisions while the city continued to improve nucleic acid screening plans and detection capabilities.

Wu Jinglei, director of the Shanghai Municipal Health Commission, said the record high infection number showed that the grid-screening plan of residents in the city since Friday is working.

Shanghai has categorized its communities as medium or low-risk grids for the virus' spread and started screening by the grids since the beginning of the week.

"Data analysis showed that the current wave in the city includes scattered infections in communities and hidden virus spread chains. The measures taken can help us stop potential virus' spread in the neighborhoods and curb its further spread in the society," said Wu.

He said more than 21 million residents had participated in the grid-screening plan from Friday to Saturday.

"We expanded the coverage of the testing with an ultimate aim of achieving zero virus' spread out of virus transmission chains already under quarantine as early as possible," he said.

Zhu Junwei, deputy director of the Shanghai Municipal Big Data Center, said that nearly 1 million public venues, such as hospitals and shopping malls, have applied a new version of health QR codes for entrance checks since the beginning of March.

"When individuals enter these venues and scan the codes, their entrances will be recorded, which may one day help disease control workers to trace the travel history of infection carriers or cases," he said.

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