Since the Covid outbreak began more than two years ago, China has announced its biggest city-wide lock down.
The city of Shanghai will be locked down for nine days while Covid-19 testing is carried out.
The financial hub has battled a new wave of infections for nearly a month, but case numbers are not high by international standards.
The city has 25 million people and authorities wanted to avoid destabilizing the economy.
Authorities seem to have changed course after the highest number of cases in a day since the early days of the Pandemic.
The eastern side of the city will be locked down from Monday until April 1st, and the western side will be locked down from April 1st to April 5th.
Firms and factories must stop operations or work remotely if public transport is to be suspended.
The city government asked the public to support, understand and cooperate with the work of epidemic prevention and control.
The Chinese provinces have been affected by other lockdowns during the Pandemic. Due to its high population density, Shanghai is the largest locked down city to date.
It is China's commercial capital and the biggest city in the country, but it is now one of the worst-hit areas as China fights to contain a resurgence of the virus with Omicron, leading to a spike in new cases.
The port and financial hub in eastern China must keep running for the good of the economy. Half of the city will remain functioning at a time.
Millions of residents in other Chinese cities have been subjected to citywide lock downs after a relatively small number of Covid cases.
The streets of a city that has been on its knees for two weeks are now busy with panic shoppers.
I have seen people queue up in front of the shop doors as they stock up before the lock down starts.
The subway station at the end of my road will be closed on Monday. All residents will be subject to Covid testing when public transport stops.
The eastern side of the city will be affected first, followed by the western side at the end of next week.
At the beginning of the epidemic, Wuhan was sealed off. It was before Christmas. China is shutting down its financial and commercial capital.
A few days ago, officials here said that Shanghai was too important to lock down. Many residents will be wondering if nine days is enough.
The recent surge in cases in China is a challenge to China's zero-covid strategy, which uses swift lockdowns and aggressive restrictions to contain any outbreak.
China is different from other countries that are trying to live with the virus.
The Omicron variant's increased transmissibility and milder nature has led to questions over whether the current strategy is sustainable in the long run.
The cost of zero-covid has become too high, according to some people in Shanghai.
More than 4,500 new domestically transmitted cases were reported by the national health commission on Sunday.