By Zoey Zhang and Bernard Orr SHANGHAI/BEIJING (Reuters) -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 will get infected by the end of next week, while the virus sweeps through China largely unchecked. After widespread protests against strict mitigation measures, China this month began dismantling its “zero-COVID” regime, which had taken a great financial and psychological toll on its 1.4 billion people. China’s official death count since the pandemic began three years ago stands at 5,241 – a fraction o…