Covid-19 coronavirus: Alert issued for nine Melbourne suburbs; Queensland finds 'missing link'

Fragments of Covid-19 have been detected in wastewater across several Melbourne suburbs. Photo / NCA NewsWire

Fragments of Covid-19 have been detected in wastewater across several Melbourne suburbs, with residents urged to get tested if they show even the mildest signs of illness.

Victoria's health department sent out an updated alert on Thursday night which outlined nine new suburbs of concern.

Coronavirus fragments were detected in a sewage sample collected from the Altona wastewater treatment plant on March 26, the department said.

The finding follows the detection of viral fragments in a catchment in Melbourne's southeast and in the city's west.

New areas on alert include Altona, Altona Meadows, Hoppers Crossing, Laverton, Point Cook, Seabrook, Seaholme and Williams Landing.

"Anyone with Covid-19 symptoms, no matter how mild, is urged to get tested, especially if you live in or have visited these areas during these dates," the health department said in a statement.

The worrying detection comes as Queensland reports one new case on Greater Brisbane's first full day free from a snap three-day lockdown.

Premier Annastacia Palaszczuk said this morning that the new case is historical and may help solve the mystery of the recent outbreak in the Sunshine State.

"We believe this historical case is the missing link from the first cluster," she told reporters.

"So that's fantastic news."

The Queensland outbreak also prompted the cancellation of Bluesfest in Byron Bay after positive cases travelled to the popular holiday spot.

Earlier in the week Victoria's chief health officer Brett Sutton said the wastewater samples could be due to a positive case being in the early active infectious phase or because someone is continuing to shed the virus after the early infectious period.

Victoria recorded no new cases on Thursday, making it the 34th consecutive no-case day.

Brisbane was also declared an orange zone from 6pm Thursday under Victoria's permit system, less than a week after it was flagged as a red zone following news of the outbreak.

Anyone who arrives in Victoria from Brisbane must get tested within three days.

Byron Bay and Gladstone are also orange zones.