Medical experts on Monday sought to allay concerns over a rebound in the number of Covid-19 infections in Hong Kong, as they suggested that the government buy a new vaccine that targets two Omicron sub-variants.

The daily tally of new Covid infections has hovered between 4,000 and 5,000 in recent days, ending a recent downward trend, while there has been concern that new Omicron sub-variants such as BA.2.75 might worsen the epidemic situation.

Speaking on an RTHK radio programme, Kwok Kin-on, a professor of public health at the Chinese University, said there would be no need to tighten Covid measures unless there is a drastic increase in hospital admissions and deaths.

"We should focus on the number of serious cases and deaths. Even if the infection figures jump significantly, it's still appropriate to maintain the existing measures if the proportion of serious cases and deaths remain low," he said.

However, he noted the inoculation rate among elderly people is still not very high.

He suggested that the government could consider introducing the newly developed vaccines targetting the BA.4 and BA.5 Omicron sub-variants to better protect elderly people. The administration said on Sunday that it was considering an application from manufacturer BioNTech to authorise the use of the updated booster vaccine here.

Speaking on the same programme, an adviser to the government on coronavirus strategy, Ivan Hung, echoed Kwok's views, saying Hong Kong already had strong hybrid immunity against Covid from vaccination and previous infections.

He added that although the new BA.2.75 variant is more infectious and is more capable of infecting people who are vaccinated, evidence so far shows most cases are either mild or asymptomatic.

The University of Hong Kong professor agreed that new vaccines targetting Omicron strains would be better than the ones now used in the SAR.

"Even though the BA.4 and BA.5 vaccine may not match the new BA.2.75 variant completely, the efficacy is still better than the first-generation vaccine," he said.

Health officials had previously warned that the new BA.2.75 variant might cause a jump in Covid infections as seen in places such as Singapore.