A new Omicron subvariant has been detected in a Melbourne wastewater catchment - the first time it has been found in Australia.
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The subvariant, which is still to be identified as either BA.4 or BA.5, was found in samples taken from the Tullamarine catchment in the city's north-west.
As of March, the BA.4 subvariant had been detected in South Africa, Botswana, Denmark, and the United Kingdom, while BA.5 cases have been primarily detected in South Africa, with a single case in Hong Kong.
Both the BA.4 and BA.5 strains are still rare, with very few samples of the subvariant available for epidemiologists to study.
The World Health Organisation (WHO) said less than 200 sequences of the new strains had been collected.
From preliminary data, epidemiologists believe BA.4 and BA.5 are similar to other Omicron strains in nature.
Speaking at a media briefing on Wednesday, lead WHO epidemiologist Maria Van Kerkhove said while scientists would continue to track the new strains, initial findings showed few differences between BA.1 and BA.2 strains and other the newer variants.
"We don't detect any changes in the epidemiology of people who are infected with BA.4 or BA.5 compared to previous sub-lineages of Omicron," Dr Van Kerkhove said.
"We have not seen a change in severity."
WHO director of emergencies Michael Ryan said charting the evolution of the virus would be key in the next phase of the pandemic.
"We simply cannot afford to lose sight of this virus," Dr Ryan said on Wednesday.
"As the virus goes underground we need to track it because we don't know what comes back."
Victoria recorded a further seven Covid-related deaths and 9664 new infections on Friday.
Wastewater testing in March revealed BA.2 had become the dominant strain in the state.
There are 374 patients in Victorian hospitals after contracting Covid-19. Of those, 20 are in intensive care units and four are on ventilators.
Nearly 67 percent of adults have had three doses of a coronavirus vaccine.
- ABC
