A Shanghai hospital has told its staff to prepare for a “tragic battle” with Covid-19 as it expects half of the city’s 25 million people to get infected by the end of the year while the virus sweeps through China largely unchecked.

After widespread protests and a relentless rise in cases, China this month took an abrupt shift in policies and began dismantling its “zero-Covid” regime, which has taken a great financial and psychological toll on its 1.4 billion people.