High demand for coronavirus vaccinations among newly eligible younger West Australians has been tempered by hesitancy among those aged over 50.

West Australians aged under 50 are flocking to get vaccinated against coronavirus but their middle-aged counterparts are proving less enthusiastic.

The state's rollout moved to its next phase on Thursday with people aged 30 to 49 receiving their first doses of the Pfizer vaccine at state-run clinics.

WA has gone one step further than other states in extending eligibility to people in their 30s.

Since Tuesday's announcement, 91,000 people have registered interest and 65,000 of those have made appointments.

"There's been massive interest," Premier Mark McGowan told reporters at Claremont Showground, where 1300 people were set to receive the vaccine on Thursday.

"What we're trying to do here is get as many West Australians vaccinated as quickly as possible so we can safely get through the pandemic, because we know there's always the prospect of an outbreak."

People aged 50 and over will continue to receive the AstraZeneca vaccine, which has been linked to isolated cases of a rare blood clot disorder.

This is consistent with national guidelines which balance the potential effects of the virus against the low risk of developing the blood clots.

Data from Australia's medicine regulator suggests the risk of people getting the disorder after taking the jab is about one in 100,000.

But just 25 per cent of people aged 50-59 in WA have so far come forward to get their first AstraZeneca dose.

Mr McGowan and Health Minister Roger Cook, who are both aged in their 50s, received their first AstraZeneca jabs last month.

"I've had my AstraZeneca jab and I'm waiting for my second one," Mr Cook said.

"The AstraZeneca vaccine is safe and it is effective. I just urge everyone to do the right thing."

About 60 per cent of people aged over 70 in WA have had their first AstraZeneca dose, as have 37 per cent of those in their 60s.

Mr Cook warned those in their 50s not to hold out for potentially becoming eligible for Pfizer in the future, saying the guidelines were in place for a reason.

"We want to maximise the availability of the supplies that we have," he said.

"We've got vaccines sitting on the shelves and we want to get it in people's arms."

Mr McGowan met with Scott Morrison on Wednesday during the prime minister's brief trip to Perth, where the pair discussed options for a purpose-built quarantine facility.

WA has identified four sites - Christmas Island, Learmonth air base, Busselton Airport and Pearce air base - as potential locations.

But the premier said Mr Morrison had indicated the Commonwealth didn't look favourably upon any of them.

"Each one of those has issues surrounding it but we'll continue to work on those sites and we'll look if there's any others," he said.

"But really, this is a matter that the Commonwealth need to step up on."