New COVID-19 Omicron subvariants have been found in Australia for the first time. 

A new subvariant, which will be identified as either BA.4 or BA.5, has been found in Melbourne wastewater samples. 

In recent weeks, the BA.4 subvariant has been detected in South Africa, Botswana, Denmark, and the United Kingdom, while BA.5 cases are turning up in South Africa, and a single case in Hong Kong.

Both BA.4 and BA.5 are still very rare, meaning there are not enough samples available for epidemiologists to study.

The World Health Organization (WHO) says less than 200 sequences of the new strains have been collected.

However, epidemiologists believe BA.4 and BA.5 are similar to other Omicron strains in nature. The WHO says there are few differences between BA.1 and BA.2 strains and other newer variants.

BA.2 is believed to be the dominant strain in Victoria.