New Covid-19 variants that can evade vaccine immunity on the rise

A Covid strain that can evade immunity from vaccination and past infection is expected to take over as Australia’s dominant strain within weeks.

Health authorities are expecting an increase in Covid reinfections and hospitalisations as a new strain – which can better evade vaccine immunity – becomes dominant on the east coast.

The Victorian department of health revealed on Monday afternoon the Omicron strain BA.4 and BA.5 is likely to overtake the BA.2 strain in coming weeks, after a “significant” increase of detections in wastewater catchments.

NSW Health revealed it expected the same to be true in its latest surveillance report, and in Queensland, chief health officer Dr John Gerrard said BA.4 and BA.5 was expected to be dominant within two weeks.

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Eastern states are bracing for an increase in Covid infections as a new strain becomes dominant. Picture: NCA NewsWire / Flavio Brancaleone

In its statement, the Victorian department of health explained the strain had a greater ability than BA.2 (the current dominant strain) to evade both immunity from vaccination and past Covid infection.

It warned an “increase in cases — including reinfections — and hospital admissions and deaths”.

However, there is “no evidence at this stage” that BA.4 and BA.5 causes more severe disease.

Research suggests BA.4 and BA.5 can evade immunity from vaccinations, but vaccines will still provide protection again severe disease. Picture: Lisa Maree Williams/Getty Images

American immunologist Dr Dan Barouch, an author of a new research paper on BA.4 and BA.5, explained to CNN last week that while the strain appeared to escape antibody responses of those fully vaccinated and boosted, the vaccine did provide protection from severe disease.

“Our data suggest that these new Omicron subvariants will likely be able to lead to surges of infections in populations with high levels of vaccine immunity as well as natural BA.1 and BA.2 immunity,” he said.

“However, it is likely that vaccine immunity will still provide substantial protection against severe disease with BA.4 and BA.5.”

How do we know BA.4 and BA.5 will takeover?

Victoria first identified BA.4 and BA.5 in wastewater catchments in April and it has risen from under five per cent in late May to 17 per cent by June 23.

On Thursday last week, NSW Health reported that the proportion of specimens in the state likely to be BA.4 or BA.5 “increased substantially” in the week ending June 18.

It was around 31 per cent compared to 23 per cent at the end of the previous week.

Victorian health authorities strongly recommend wearing masks in shared indoor settings if you can’t physically distance, and remind people they are required on public transport. Picture: NCA NewsWire/Sarah Matray

Looking overseas, in South Africa – where Omicron was first identified last November and quickly spread globally – a “fifth Covid wave” was recently attributed to BA.4 And BA.5.

This was despite research showing 97 per cent of the population had antibodies due to previous Covid infections or vaccination, Bloomberg reported.

In the US, BA.4 and BA.5 caused about 35 per cent of new Covid infections in the week ending June 18, up from 29 per cent the week before, according to the US Centers for Disease Control and Prevention.

The dominant strain in the US is BA.2.12.1, which caused 56 per cent on infections in the week ending June 18.

Originally published as New Covid-19 variants that can evade vaccine immunity on the rise