Health authorities have warned that daily Covid case numbers are expected to climb further, leading to a possible new wave of infections over the winter.

A total of 6,210 local infections and 179 imported cases were reported on Saturday, the third day in a row that the number topped the 6,000 mark.

Over 1,900 Covid patients are currently receiving treatment in hospitals, including 266 new admissions. A dozen are in intensive care.

Albert Au from the Centre for Health Protection (CHP) noted that the proportion of cases involving the Omicron sub-variant BA.5 had risen to 30.2 percent.

He said the sub-variant's prevalence in the community could be behind the recent spike in infections.

"We expect that in the near future, we will have a higher percentage of BA.5 cases, and that will cause cases to grow further," Au said. "This mirrors the trend in other countries. When the percentage of BA.5 cases exceeds a certain level, then the rise [in cases] can be very sharp, and very soon it will replace other sub-lineages to be the mainstream."

He also cautioned against another surge of infections later this year, as immunity among recovered patients who have had the virus would begin to wane.

"It's been [months] since we had the peak of the fifth wave," Au said. "For many of the [recovered] confirmed cases, if they have not been fully vaccinated, then the risk of re-infection can be high. So we are worried that as we enter into winter, there will be another wave of outbreak."

Five more patients, aged between 55 and 99, have passed away. None were fully vaccinated.