WA Premier Mark McGowan has said he hopes the state is past its COVID-19 peak, but that it will take another week to be certain.
Higher case numbers in WA tend to be reported on Wednesday and Thursday each week, including the state's record high of 9,754 cases last Wednesday, followed by a similar number the next day.
Since then, cases have hovered between 6,082 on Monday and 8,731 yesterday.
There were 7,998 new infections reported today, with the number of active cases continuing to drop.
Hospital figures, including for intensive care, have remained relatively steady over that time, with 256 people in hospital yesterday, including eight in ICU.
But Premier Mark McGowan was careful to not call the crest too soon.
"That will give us a good indication on where we're going."
Surveillance report shows Omicron wave slowing
The latest COVID surveillance report, released by WA Health, shows WA's Omicron wave is starting to slow.
Last week, the number of new cases grew by 6 per cent, down from 30 per cent the week before.
"While the rate of increase of case numbers appears to have started slowing, it is still too early to determine when the peak will be reached, particularly while the proportion of positive PCR tests remains high," the report says.
The rate of COVID within the community was last week the highest in the nation, with the exception of Tasmania.
The virus is also spreading through the Aboriginal population at a rate 2.5 times higher than the rest of the population, according to WA Health.
The report found case rates remained highest in the Kimberley, followed by the Pilbara and Goldfields.
Surge predicted if mask mandates eased
It comes after modelling from the Telethon Kids Institute suggested WA's current Omicron outbreak could grow by 15 per cent if mask mandates were removed before Easter.
The opposition and business groups have been calling for that to happen as soon as possible, but the institute's Peter Gething said now would be the worst time to do so.
"We're at the maximum level of infection in the community … so we want to keep every protective measure we can in place," he said.
"Obviously the later in the curve you leave it to remove the mask mandates, the lower that public health impact's going to be."
The modelling, conducted in partnership with Curtin University, was described as "the most detailed COVID-19 modelling ever applied to an Australian outbreak".
It found that if masks were only required in hospitals and aged care from next Thursday, the state could also see about an extra 100 COVID deaths — or an increase of between 17 and 30 per cent on what had been expected — between that point and the start of August.
Researchers said that provided a solid reason to keep mask rules in place, although they identified children as the first group that could lose the masks when the time was right.
That was because children are becoming infected earlier in the outbreak, giving them acquired immunity sooner.
No undetected cases among snap tests
The modelling took into account data from a range of government authorities, Google, and a study run by the Institute to try to discover how much COVID-19 was going undetected in the community.
Of the 396 people tested, all returned negative results.
Researchers said that indicated about three-quarters of all infections were being detected by the health system, far more than was expected.
Speaking alongside federal Opposition Leader Anthony Albanese on the campaign trail today, Mr McGowan said he was "heartened" to hear so many cases were being picked up.
"We're the only government in Australia that have given households free RATs across the board, and that's obviously paying dividends," he said.
Masks and 5,000-plus cases set to linger
When asked about removing masks, the Premier gave no indication of when that was likely to occur, or whether school children would be exempted first.
"We know that masks work. They reduce the spread of the virus, they reduce the pressure on our hospitals," he said.
"I know everyone wants us to be definitive at every point in time, but what you find is if you're too definitive too early, and circumstances change, then you have to change your position and people get upset by that."
The Telethon modelling also found that if current restrictions remained, WA was set for a long tail, with daily cases likely to remain above 5,000 for the next month and a half.
"Those numbers will bounce around a little bit in the coming week or two," Professor Gething said.
"But we won't see this distinct turning point where suddenly cases start crashing.
"It's going to be a slow return to normal."
When asked about a longer plateau, Mr McGowan said WA was in a different position to other states because of its high vaccination rates.
He said about 86 per cent of those eligible to receive a booster had already received their third jab.
Opposition leader Mia Davies continued her calls for the government to outline when restrictions will be eased, particularly around masks.
She acknowledged the Telethon Kids Institute's research, and conceded any changes needed to be made when it was safe to do so.
"We actually just want the Premier to share with us when those restrictions, the public health restrictions and any of the mandates, are going to be removed or parred back," she said.
Earlier this week, the Premier said he expected Perth Stadium would be back at full capacity in time for a Rugby Union test between England and the Wallabies in July.
Ms Davies said that showed the government was prepared to give indications about the future of the pandemic in some situations.
"They seem pretty certain that they're going to have 100 per cent capacity at Optus Stadium for an international sporting event," she said.
"They do have information and modelling that they could share."
