‘Stealth’ Covid variants able to evade vaccines set to become predominant

‘Stealth’ Covid variants that are able to evade vaccines are set to become predominant in Victoria as winter approaches.

New stealth variants that are more resistant to current vaccinations are set to become predominant within months, Victoria’s chief health officer says.

On Saturday, Victoria’s Department of Health warned it had detected Omicron strain sub-lineages in wastewater samples.

“The BA.4 or BA.5 sub-lineage of Omicron is being detected at increasing frequency at low levels in wastewater samples,” a statement said.

“There have been 33 wastewater detections at Tullamarine Airport and residential catchments in metropolitan Melbourne and the Greater Geelong area since mid-April.”

The department said the Omicron BA.2.12.1 sub-lineage had been detected in 12 wastewater samples in Victoria since April.

It warned early evidence suggested Omicron sub-lineages BA.2.12.1, BA.4 and BA.5 were more able to evade immunity from earlier Covid-19 infection and vaccination.

“There is no evidence to suggest that they cause more severe disease,” the statement said. “These sub-lineages are unlikely to be at levels in Victoria that contribute to rising Covid-19 cases at this stage.”

Omicron negative stain images created at the Doherty Institute. Image: Dr Jason A Roberts, Head, Electron Microscopy and Structural Virology, Doherty Institute

There were 11,925 new cases of Covid-19 recorded in Victoria on Friday, and 21 deaths.

“This brings the total number of deaths in Victoria since the pandemic began to 3237,” the department said.

There were 552 Covid-19 cases in hospital in Victoria, with 21 active cases in ICU, including seven on a ventilator, and an additional four cleared cases in ICU.

Chief health officer Professor Brett Sutton told the Herald Sun on Friday Covid cases would remain in the thousands for months to come and Victorians needed to “buckle up and keep at it”.

While the Omicron sub-variants only represent a small proportion of current cases, Prof Sutton said the new variants would remain an “ongoing challenge” and would create “upward pressure” as their numbers grow.

“Whether it’s BA4 or BA5 or BA2.12.1, one of them will become predominant over the coming months,” he said.

“I don’t think it’s driving numbers at the moment . . . and probably won’t be until July or August that they might be really significant numbers.”

He also highly recommended people wear masks indoors.

Originally published as ‘Stealth’ Covid variants able to evade vaccines set to become predominant