Victoria's COVID-19 testing sites are buckling under the pressures of soaring temperatures and caseload.
The state set another coronavirus record on Thursday, with the number of new daily cases jumping by more than 1300 to 5137.
Another 13 people in the state, aged from their 50s to their 90s, have died with the virus, authorities confirmed on Thursday.
Testing sites across the metropolitan area continued to close on Thursday because they are over capacity and the Department of Health has warned a series of hot days could make the situation worse.
"Some testing sites may need to close over the next three days due to excessive heat, particularly those located outdoors in tents," Chief Health Officer Brett Sutton's daily update email says.
"Temperature inside the tents can rise even 10 degrees higher, and testing staff work in full PPE."
The number of active Victorian coronavirus cases has grown to 23,833, with more than 20,700 active close contacts in isolation.
More than 81,000 tests were processed on Wednesday.
There are 55 people with the virus in intensive care, with 395 in hospital and a seven-day hospitalisation average of 378.
However, there are fewer people on ventilators - 23 on Thursday, down from 28 on Wednesday and 33 on Tuesday.
Victoria's COVID testing system continues to struggle, with multiple testing sites again closing after reaching capacity early on Thursday morning.
Victorian Premier Daniel Andrews joined a national cabinet meeting on Thursday to discuss a uniform definition for a close contact of an infected person and the use of rapid antigen tests to ease the testing burden.
Fully vaccinated positive cases will be able to leave isolation after seven days of being tested but will need to return a negative rapid antigen test on day six.
The common definition of a close contact will only cover household or intimate contacts who spent more than four hours with a positive case, and symptomatic close contacts will still need to take a PCR test.
The City of Melbourne has cancelled its drone swarm at Docklands as part of its New Year's Eve celebrations, citing the pandemic's ongoing impact on freight, logistics and staff training. Other entertainment is going ahead.
Melbourne Lord Mayor Sally Capp said people in general are starting to return to the CBD after six lockdowns.
"We've been really encouraged by the pedestrian numbers that we've seen certainly in the lead-up to Christmas," she told reporters.
"Our best Saturday we're at 96 per cent of pre-COVID foot traffic which is really fantastic, it's that sense of Melbourne being back to normal."
Where to get a COVID-19 test in Victoria:https://www.coronavirus.vic.gov.au/where-get-tested-covid-19