A block of 83 apartments in the Wollongong CBD that includes accommodation for homeless people has been deemed a high-risk premises and locked down because of COVID-19 cases within the building.
A declaration that the Keira Street building be closed, signed by deputy chief health officer Dr Marianne Gale, came into effect at 8am Friday.
The Illawarra Shoalhaven Local Health District has confirmed that five residents have tested positive for COVID.
The building is considered a "high COVID-19 risk premises" because of the risk of transmission between residents, and the declaration will remain in effect until 8am on October 1 - a period of 14 days.
"In this building there is a community of residents who move between apartments and use communal areas," Illawarra Shoalhaven LHD chief executive Margot Mains said.
"The residents' close and frequent interactions are similar to those in a household and, as a result, all residents of the apartment complex are considered close contacts."
Ms Mains said health clinicians and other support services would remain on-site throughout the isolation period.
"All residents will be closely monitored and appropriate care is being provided, including telehealth consultations, in-home medical care and transport to hospital for those needing higher levels of care," she said.
Other support, such as food and other essential items, and counselling are being provided.
Wollongong Homeless Hub, which operates out of the building, has had to close its drop-in centre and emergency accommodation as a result.
It leases 30 of the block's apartments, most of which accommodate private residents.
While the local health district is managing the welfare of residents during the lockdown, Wollongong Homeless Hub staff are staying in contact with their clients.
President Bill Simpson said staff were reassuring those residents who were clients about the situation.
"Our main concern is our clients in the building," Mr Simpson said.
"They will be anxious about what's happening... A number of them have mental health issues and other medical issues."
Under the relevant public health order, the residents of the apartment block cannot leave their home unless there is an emergency or they are directed to by an "authorised medical practitioner" or the police commissioner.
No one is allowed inside, either, unless they are a police officer, providing medical care, testing for or vaccinating against COVID, or providing a necessary service.
There was a police presence outside the building on Friday morning, as well as people wearing personal protective equipment.