Western Australia has officially recorded more than 700,000 COVID-19 cases in the past five months.
But modelling by the Telethon Kids Institute and Curtin University suggests the true figure might be closer to 850,000 due to asymptomatic cases and some people who failed to get tested or report their results.
The research team has forecast Western Australia's Omicron outbreak will infect 1.2 million people by the time it has worked its way through the state.
Associate Professor Ewan Cameron said Western Australia was 72 per cent, or about three-quarters, of the way there.
Dr Cameron is also confident WA is past its peak and will not reach the 25,000 daily cases the Chief Health Officer had previously warned of.
But he said the peak of 17,105 recorded on May 19 was higher than anticipated.
"The biggest surprise to us was that the case numbers did go significantly above where we thought they would go upon the mask mandate being removed," Dr Cameron said.
"That was a surprise, as far as having perhaps underestimated the amount of mixing that would have taken place.
"We saw increased mixing and socialisation after masks were removed, as well as workplace attendance."
"But the fact that cases have dropped down now, since the last two weeks of very high case numbers, suggests the epidemic curve is essentially playing out as expected."
Yesterday's 9,948 new cases was the lowest daily figure WA has recorded in nearly three weeks and a 35 per cent drop on the previous Friday.
Today the number was even lower with 8,665 new cases.
The number of West Australians in isolation is also falling.
On Sunday there were more than 90,000 active cases in the state, but there are now fewer than 70,000.
Daily cases of COVID are expected to continue falling in WA, but not as quickly as in recent days, with the decline expected to slow to about 10 per cent each week.
The state is expected to see more than 1,000 daily cases until mid-July.
"Our model looks out towards case numbers not coming down to truly pre-border opening levels until the end of July," Dr Cameron said.
"But as far as the end of the outbreak is concerned, that depends on when the load to the health system gets to more manageable levels."
"We have this uncertainty around what winter will do, and while Omicron cases are declining, we still have large amounts of influenza circulating."
Yesterday, WA's hospital system remained short of 3,000 staff due to COVID-19, a slight improvement on 3,500 earlier in the week.
Price hike in flu jabs behind WA freebie delay
The state government has said it is still working to secure the supplies to be able to provide more free influenza vaccinations to West Australians. It follows the Queensland government announcing flu shots will be free there.
"We've seen a substantial spike in the price of those vaccines, perhaps in anticipation of governments following that decision that was made in Queensland," Deputy Premier Roger Cook said.
"Obviously, we don't want to necessarily be victims of that price spike, but look, this is in the hands of everyone in the community, not just the government."
"Go to your pharmacist, go to your local GP, go to your public health clinic, get yourself vaccinated for the flu."
Mr Cook cautioned West Australians had not had much exposure to influenza in recent years and could be particularly susceptible.
Meanwhile the Institute for Respiratory Health in WA has joined the chorus of medical professionals pleading with people to get vaccinated against influenza as soon as possible.
"We won't be able to avoid the flu, and being protected and prepared as best we can is the best strategy," the institute's Yuben Moodley said.
Dr Moodley also urged anyone who was eligible to get their next COVID-19 booster.
