In his latest published advice to the state government, Andy Robertson has pinpointed March 29 - when the state recorded 9754 cases - as the height of the outbreak.
On Thursday, WA moved to the national definition for close contacts.
Household members and intimate partners of cases still need to quarantine but cases in classrooms will no longer force children into isolation.
A 500-person cap at hospitality venues has been removed and QR code check-ins are now only required at hospitals.
But masks remain mandatory in all indoor public venues and people must continue to show proof of their vaccination status.
"The mask mandate has been very effective. It really has decreased the spread," Dr Robertson told ABC radio.
"We'd be keen to see the numbers continue to fall over the next couple of weeks before we look at removing them."
WA on Thursday recorded 8144 cases and two deaths.
About one third of the 200 people in hospital in WA were unvaccinated or had only vaccine dose, Dr Robertson said.
There were close to 55,000 cases reported in Australia on Wednesday, while the national death toll rose by 39.
In NSW alone, there were 18,265 infections, while Victoria reported more than 10,000.
Meanwhile, the Tasmanian government is in no hurry to welcome back large cruise ships.
A ban on the vessels entering Australia, in place since March 2020, will be lifted from Sunday.
NSW, Victoria and Queensland have outlined testing and vaccination requirements for passengers and crew as they prepare for the ships to return.
But Tasmanian Liberal MP Roger Jaensch on Wednesday said the island state was still reviewing whether it was safe for larger cruise ships to return.
LATEST 24-HOUR COVID-19 DATA FROM ACROSS AUSTRALIA:
NSW: 17,856 cases, 21 deaths, 1582 in hospital, 71 in ICU
Victoria: 10,462 cases, 14 deaths, 392 in hospital, 19 in ICU
Queensland: 8754 cases, four deaths, 590 in hospital, 16 in ICU
Tasmania: 1843 cases, two deaths, 50 in hospital, one in ICU
Northern Territory: 563 cases, 30 in hospital, two in ICU
Western Australia: 8144 cases, two deaths, 200 in hospital, five in ICU
South Australia: 5398 cases, one death, 238 in hospital, 11 in ICU
ACT: 1074 cases, one death, 56 in hospital, one in ICU
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