/NSW, Victoria authorities detect evidence of two new Omicron sub-variants of COVID-19 | 7NEWS

NSW, Victoria authorities detect evidence of two new Omicron sub-variants of COVID-19 | 7NEWS

Australia could be on the cusp of a COVID-19 double-whammy, with authorities finding evidence of two new strains of the virus.

A person who travelled from South Africa into NSW has been identified as the first person in Australia with the BA.4 sub-variant of Omicron, while Victoria’s health department has detected the BA.2.12.1 Omicron strain in Melbourne wastewater.

Former World Health Organisation adviser Adrian Esterman said the emergence of the two new strains in Australia will likely lead to more COVID-19 cases because they are “much stronger” than the current dominant strain BA.2.

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However he believes hospitalistion rates could be similar.

“What we know about BA.4 is that it 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,” University of South Australia epidemiologist Esterman told 7NEWS.com.au.

“This comes just at the stage we’re removing all our public health measures. That’s the bad news.

“The good news is so many people have been infected now and those who haven’t been infected probably have quite good immune systems from being vaccinated, so we have got a bit of protection from major increases in cases from these two sub-variants.”

The traveller arrived in the week ending April 2, with their sub-lineage reported by NSW Health on Thursday after “routine genomic surveillance” which involves examining the person’s PCR test.

NSW Health indicated it was unknown if it is the only case of the variant in Australia.

“Whole genome sequencing is conducted on a sample of PCR positive tests in NSW,” the authority said.

“This is not a random sample, therefore the proportion of variants identified is not necessarily reflective of their distribution in the community.

“NSW Health continues to closely monitor the evolving situation with COVID-19.”

Overseas evidence

The BA.4 strain, declared a variant of concern by the World Health Organisation (WHO), has been linked to an uptick of cases in South Africa.

The country has been recording approximately 4000 to 6000 COVID-19 cases a day in the past few days, up from a few hundred just a few weeks ago.

Durban-based epidemiologist Salim Abdool Karim believes BA.4 is behind the rise, but noted “it’s too early to tell whether BA.4 is going to cause a fully-fledged wave”.

University of Queensland infectious disease physician Paul Griffin was almost certain there would be more cases of the sub-variant than the one detected in NSW, but it’s too early to sound the alarm.

“It’s not really a concern of any great magnitude. We know this is what this virus is going to keep doing,” he told 7NEWS.com.au.

“And at this stage, it would appear our vaccines still provide good protection, we just need to focus on getting the basics right, getting those boosters and fourth doses up.

“For a variant or sub-variant to become dominant, it really needs to be more infectious so it essentially outcompetes the existing variants that circulating.

“There have been a large number of variants or sub-variants that have emerged that haven’t had those properties and just dwindle away.”

WHO said a fortnight ago it was investigating BA.4, as well as another strain dubbed BA.5, after they were detected in South Africa and Europe.

However WHO lead epidemiologist Maria Van Kerkhove noted there was no evidence of “any change in epidemiology or severity” in the strains.

But more research is needed, particularly with how much protection vaccines will provide.

“We really have to wait to see what happens in the community, in the population, to see whether it takes over and if the types of illnesses it causes is different,” Griffin said.

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The Victorian health department reported on April 15 that BA.4 or BA.5 had been detected in wastewater samples taken from the Tullamarine catchment.

On Friday, the department said there had been no further detections.

However it reported the detection of the BA.2.12.1 Omicron strain in a southeast metropolitan Melbourne wastewater catchment.

It also noted BA.2.12.1 appears to be “more transmissible” than the current dominant BA.2 strain, according to early evidence.

The strain is growing in the US, although BA.2 remains dominant.

The Centres for Disease Control has found the BA.2.12.1 accounts for 28.7 per cent of new cases in the week to April 23, up from 19.6 per cent in the previous week.

Bring back restrictions?

Esterman said the reintroduction of COVID-19 restrictions in Australia could be necessary.

“If we shut our borders to all of Africa, because it’s also in Botswana, then perhaps we could delay it,” he said.

“But we won’t do that.

“And that means we’re almost certain to get the BA.4 in Australia.

“We just have to wait and, if necessary, we introduce some public health measures.”