The figures have been produced by University of Western Australia professor George Milne, an expert in infectious disease modelling who predicts WA's outbreak will peak within about two months of the borders reopening.

WA's government is yet to release any of its own modelling on the impact of the Omicron variant which is already circulating within the state.

The borders had been due to open on February 5 before Premier Mark McGowan announced an indefinite delay, citing the need for more people to get their third vaccine dose.

Prof Milne told ABC radio on Friday it would be difficult to improve the level of immunity that would be present in the population by that date.

"There's a point where it doesn't make much difference if we delay," he said.

"I wouldn't be surprised if we're in a position to reopen the borders not too much later (than February 5)."

Prof Milne and his team did not model overall case numbers but predicted WA would have a peak of 430 hospitalisations, with about 10 per cent of those patients requiring intensive care.

"That's the real concerning number I think, and this is the number that we really need to get our heads around," he said.

Prof Milne's figures have not yet been peer-reviewed.

WA Health has said the state has a surge capacity of about 300 extra intensive care beds, although concerns have been raised about whether they could be adequately staffed given the state's shortage of doctors and nurses.

Chief Health Officer Andy Robertson expects 35 per cent of eligible West Australians will have received their booster dose by February 5. That rate is predicted to increase to 75 per cent by early-March.

"Beyond (March), the waning of protection from boosters is anticipated to offset this gain, particularly among the elderly and healthcare workers who were boosted early, and decisions on future dates would require further modelling," Dr Robertson wrote in a letter to the premier last week.

Australian Associated Press