The forced lockdown of a Melbourne townhouse complex after the discovery of two new coronavirus cases was an "extreme" but necessary measure, a health expert says.
Professor Mary-Louise McLaws backed the apartment complex lockdown.
Epidemiologist Mary-Louise McLaws told Today authorities had to act promptly after Victoria yesterday recorded cases linked to a Southbank residential complex.
"We shouldn't be taking this lightly. I can only congratulate Victoria for shutting down when it did," Professor McLaws, from the University of NSW, said.
The Southbank townhouse complex linked to new COVID-19 cases.
"It feels extreme. But if they (the cases) are very well connected, and it's an apartment block where a lot of people may socialise and know each other, it may well be important to do, like they did in North Melbourne last year.
"It's unpalatable but it is necessary."
Professor McLaws said authorities had to determine if the cluster was from the Delta or Kappa variant but both were "incredibly hard to contain".
The state's two new COVID-19 cases are men who live in separate apartments adjacent to the other positive cases.
The cases were identified yesterday afternoon following a testing blitz set up for the townhouse complex on Monday where more than 200 residents were tested.
Health teams inside the Southbank apartment complex.
Health authorities say the complex is a place they're most concerned about in this outbreak.
Professor McLaws said the new cases show how important it is for restrictions to be eased gradually together with a vigorous vaccination drive for younger Victorians.
"Restrictions need to be lifted really slowly and vaccination numbers need to be lifted," she said.
"The most important group at the moment is the 20- to 39-year-olds.
"They are the ones that carry most of the risk of infection. Therefore, most of the risk for transmitting it."
More than 200 residents were tested in the Southbank complex.
The Southbank townhouse cluster now sits at six cases after it was revealed on Monday a man caught the virus from an Arcare Maidstone Aged Care worker who lived in the same building.
Primary close contacts will expand from the original 61 residents to about 200, who will also be asked to lockdown for the next 14 days.
The complex has just over 100 apartments and has "multiple access points" into the building.