Dr Ho Pak-leung said the Covid situation in Hong Kong remains unstable, as more than 40 percent of the recent local cases are without a clear source.
He told an RTHK radio programme that although the city recorded single-digit cases on three days during the past week, it was probably only because less testing was done during the Chinese New Year holiday.
Health officials reported 20 new Covid infections on Sunday – the highest figure seen in the last week.
Ho warned there may be a further rebound in infections if people let their guard down after the easing of anti-epidemic measures last Thursday, including a resumption in dine-in services at restaurants after 6pm.
Health Secretary Sophia Chan echoed Ho’s views, saying more gatherings during the Lunar New Year holidays could pose infection risks.
But she told RTHK more time is needed to access the situation, adding that the government’s move to relax certain social restrictions were done in a gradual and “more targetted” manner.