Hong Kong is expecting 12 new coronavirus cases on Tuesday, according to a medical source, as the Hospital Authority chief vowed to test all patients admitted.On Monday, the city reported nine cases, matching the figure recorded a week earlier, both marking daily lows since July 3.The official tally of infections stood at 4,810, with 89 related deaths. So far, about 20 per cent of patients have been found to be asymptomatic and not among high-risk groups.More than 10,000 Hong Kong residents…