Local lockdown as Sydney cluster grows

The Covid-19 cluster hitting Sydney continues to grow. Photo: US National Institute of Allergy and Infectious Diseases

Sydney's northern beaches will enter lockdown from Saturday evening as the coronavirus cluster in the area grows to 41 cases.

From 5pm on Saturday until midnight on Wednesday, the local government area will revert to lockdown orders issued across the state in March.

People will only be permitted to leave their homes for five basic reasons: to seek medical care, exercise, grocery shop, work or for compassionate care reasons.

An additional 23 cases were recorded in the 24 hours to 8pm on Friday, including 10 already announced.

That takes the cluster to 41 cases.

All bar two of the new cases have already been linked directly to the Avalon cluster.

Premier Gladys Berejiklian says the restrictions are essential if Sydney has any hope of a semi-normal Christmas.

"We're hoping that will give us sufficient time to get on top of the virus, so that we can then ease up for Christmas and the New Year," she said.

Ms Berejiklian also urged northern beaches residents not to panic buy.

"It's okay to go out and do essential shopping so don't panic buy, please."

Greater Sydney residents are also asked to abandon all non-essential activity.

The premier hinted citywide restrictions could yet be imposed.

The new cases come as NSW Health asks hundreds of gym goers on Sydney's northern beaches to get tested and isolate immediately.

Authorities issued a public health alert on Saturday morning, calling several hundred people who attended an Avalon gym to take urgent action.

A known case attended Anytime Fitness on Avalon Parade on December 6, 7, 8, 11 and 12 while infectious.

Investigations are underway and authorities are in the process of tracking down close contacts but are asking anyone who attended the gym on those days to get tested immediately and isolate until further advice.

The gym adds to a lengthy list of venues visited by confirmed cases published by authorities on Friday afternoon.

Other states acted on Thursday and Friday to prevent the cluster jumping borders, with more barriers for NSW residents erected by Western Australia, Victoria, Queensland, Tasmania and the Northern Territory.

Anyone who enters WA from NSW will be forced into 14 days of self-isolation and people who have been in the northern beaches will not be able to enter Victoria or Queensland without quarantining.

Genomic sequencing has connected the cluster to a US strain of the virus, which may have entered NSW in a returned traveller in early December.

That traveller has never left the hotel quarantine system, meaning the connection between that case and the northern beaches remains unclear.