Canberra, Apr 30 (IANS): Health authorities of Australia's Victoria state confirmed that the Omicron sub-variant BA.2.12.1 has been traced in wastewater in Melbourne.

The Victoria Health Department said authorities would now prioritize the sequencing of PCR samples from Covid-19 cases in the water catchment area to get a better understanding of the spread of the BA.2.12.1, reports Xinhua news agency.

"Early evidence suggests it is more transmissible than BA.2 but does not cause more severe disease."

The BA.2.12.1 sub-variant is currently on the rise in the US, which makes up nearly 30 per cent of sequences identified nationally, according to the Centers for Disease Control and Prevention, and is also fast spreading through Europe.

Victoria reported 19 Covid deaths on Saturday along with 9,064 new cases, bringing the state's overall active cases to 54,992.

There are 448 people hospitalised with Covid in the state, 30 of whom are in intensive care units.

The BA.2.12.1 detection came only a day after the first case of another Omicron sub-variant, BA.4, was found in the neighbouring state of New South Wales (NSW) in traveller from South Africa.

The sudden simultaneous arrival of the two virulent strains is already causing concern among medical experts such as epidemiologist Professor Adrian Esterman from the University of South Australia.

"BA.2.12.1 now accounts for 25 percent of cases in the U.S. BA.4 is rapidly becoming the dominant strain in South Africa. Increasing case numbers will inevitably result in increased hospitalizations and more people with long-Covid. This is real and happening now," Esterman tweeted.

Speaking to local media, Esterman said BA.4 "appears to escape the immune system a bit better than BA.2, so that means that people who've already been infected can be re-infected more easily, and people who are vaccinated can be infected more easily".

"This comes just at the stage where we're removing all our public health measures - that's the bad news," he said.