The government has admitted it is struggling to contain the fifth wave of infections, fuelled by Omicron. But it has ruled out a city-wide lockdown.
A record 4,285 new cases were reported on Wednesday.
Chinese President Xi Jinping urged the local leaders to take "all necessary measures", in a rare intervention.
The comments may signal tighter controls in China's special administrative region, which pursues a zero Covid policy - but without the strict mass testing and lockdowns seen in mainland China.
More than 10,000 people are waiting to be admitted to hospitals, as experts warn cases could surge to 28,000 daily. Nine people died from the virus in the past 24 hours, including a three-year old girl, authorities say.