WA Premier Mark McGowan on Sunday announced he wanted to avoid another lockdown at all costs after a hotel quarantine guard tested positive on Saturday.

He instead introduced a raft of new restrictions in his state to help reduce the risk of a coronavirus outbreak.

“We cannot underestimate this virus. We cannot be complacent. We need to follow the health advice. We need people to get tested. And we need everyone to keep wearing your masks,” he told reporters.

“I want to avoid going into lockdown again. I know how much it can impact people’s lives and businesses but if we need to go back into lockdown we will. That decision will be based on the latest health advice but currently, at this point in time, we can avoid a lockdown, purely based on the restrictions in place over the past weeks and the requirement people have to wear masks. It has significantly reduced the risk of transmission.”

To “protect the West Australian community”, the Premier said they’d made the decision to not permit spectators at the AFL Derby at Optus Stadium this afternoon.

“I understand people will be disappointed and some people will be frustrated but the decision has been made on health advice and we have tried to communicate this as quickly as possible,” he said.

“The game will still go on and of course people can watch it from their own homes. The decision to have no crowd at the stadium also helps us in preventing possible transmission on public transport. Having 45,000 people try to get to Optus Stadium at the same time is too much of a risk, especially as we are still going through the close contacts.”

Nightclubs will also be “closed immediately” in WA “in addition to the no crowd decision”.

Asked if the state could “still be headed” for a lockdown this week, Mr McGowan said “it is a prospect”.

“But what has saved us from having a lockdown immediately is during the course of this week, last week, when these people were in the community, we were in a state of semi-lockdown, everyone was wearing masks, and we had a very quiet society,” he said.

“And that has avoided it at this point in time. Had what happened in the last couple of days occurred three weeks ago, we would have gone into lockdown immediately. But the situation was somewhat different because of the fact we are already in a very precautionary state across Perth and Peel region.”

Mr McGowan foreshadowed a potential lockdown on Saturday when a hotel quarantine security guard – and then two of his seven housemates – tested positive to COVID-19.

The security guard, a man in his twenties who lives in Nollamara, had already had his first dose of the coronavirus vaccine, Mr McGowan said.

He had worked in the Pan Pacific Hotel on April 24, 25 and 26, during which time new arrivals were admitted to the hotel, and worked on the same floor as two returned travellers who had tested positive.

“CCTV vision is being reviewed, however there is no clear explanation at this point as to how the security guard could have been infected,” the Premier said.

“It is possible transmission could have occurred while the international arrivals were admitted into hotel quarantine and possibly were transferred to their rooms. This is being investigated further.”

The man’s household included two guests from Canberra, Mr McGowan added.

The potential for a second lockdown comes not even a week after the Perth and Peel regions were sent into a three-day circuit breaker over the Anzac Day long weekend, following a breach in the WA capital’s hotel quarantine system.

Ending last Monday at midnight, Mr McGowan had defended the circuit breaker – brought on by just two cases – saying he didn’t want to “see what happened in America or Britain or India or Brazil happen here”.

“I think people watch on the news every single night what is occurring in other countries around the world and they know we don’t want that to happen here,” he told reporters, quizzed over his trust in his state’s contact tracing and health system.

“There’s two places in the world, countries of significant size that have avoided that, and that’s New Zealand and Australia. And that’s basically because we have used our isolation, our borders and our measures using our public health initiatives to good effect and I want that to continue.”