A more infectious strain of the Omicron variant that arrived from South Africa last month may soon be dominant in Australia, federal government's health professionals say.
The more infectious BA.2 subvariant was first detected in South Africa, and was first found in Australia in a Queensland patient last month.
Deputy Chief Medical Officer Professor Michael Kidd said it was too early to tell whether the BA.2 subvariant caused more severe disease.
However, he said if it did, it might be categorised as a new variant.
"If this BA.2 subvariant is shown to have more distinct clinical characteristics, then the World Health Organization [says it] may become a variant of its own, but it is too early to speculate on that," he said.
Professor Kidd said health officials had not yet seen evidence of more severe disease or reduced vaccine efficacy associated with the subvariant, but stressed it was too early to tell.
He said UK health officials reported overnight the BA.2 subvariant had a "growth advantage" over other Omicron subvariants.
He also noted that reports from Denmark and elsewhere suggested: "It may be becoming the dominant subvariant of Omicron."
The subvariant has earned the nickname the "stealth subvariant" because mutations in its genetic code initially made it difficult to detect as a strain of Omicron.
4 million more Australians able to get boosters
Health Minister Greg Hunt noted that 4 million more Australians became eligible for a COVID-19 booster shot today.
The recommended wait between receiving a second dose of the vaccine and a third shot has been reduced from four months to three from today.
Mr Hunt said vaccine supplies for boosters were ready, but he advised people to call around if an individual pharmacy or doctor was booked out.
Mr Hunt also said the government had planned its vaccine-purchasing agreements for a fourth round of vaccinations in case that was needed, but the issue was still being considered.
