A recent spike in COVID-19 cases brought on by the new Omicron variant XBB could trigger a fresh wave across the country, health authorities have warned.

Chief medical officer Paul Kelly said the government is on alert for rising case numbers and are closely monitoring a second Omicron variant BQ.1 overseas.

“While evidence is still emerging, the experience to date with these two variants overseas is that they do not appear to pose a greater risk of severe illness and death – and that the COVID-19 vaccines provide good protection against these outcomes,” Professor Kelly said in a statement on Tuesday.

However he added that the new variants are vaccine-resistant and can also evade the immunity provided by prior infection.

On Friday in the weekly COVID-19 update, Victorian chief health officer Brett Sutton said the subvariants accounted for 13 per cent of clinical samples in the past month.

Continued growth at these rates would see these subvariants become the dominant subvariants in Victoria, he warned.

NSW chief health officer Kerry Chant also echoed concerns about the subvariants.

Members of the public are being urged to take extra precautions to help reduce the size of a potential new COVID wave.

The Department of Health recommends wearing a mask when needed, getting a third or fourth vaccine dose and staying home when unwell.

– AAP