Victorian health authorities are racing to trace the movements of a Melbourne teacher, with fears she may have been infectious in the community for a week before testing positive for the virus.
A testing blitz began on Wednesday after a female teacher at Al-Taqwa College in Truganina tested positive for COVID-19.
The school has been temporarily closed with more than 2000 students and 300 staff ordered to get tested and isolate.
The teacher, aged in her 20s, is currently isolating and being interviewed by contract tracers, with urgent investigations underway into how she contracted the virus.
She lives in the Hobsons Bay area with her husband, who was also undergoing testing on Wednesday night.
Victoria's COVID Testing Commander Jeroen Weimar said the woman became symptomatic at the end of last week and may have been infectious in the community for a week before testing positive.
“We're working on the basis that Wednesday, Thursday, Friday last week, so the 28th, 29th, and 30th [of July], we're assuming that's the point in time when she may have been infectious,” he told ABC Radio Melbourne.
Given there were some exposure sites listed in the Hobsons Bay area, “there may be some connection points there”, Mr Weimar said.
Al-Taqwa College was also a significant location for transmission in last year's second wave.
In a statement on Wednesday night, the school said the campus would be locked down for 14 days, with online classes until August 18 unless the health department advises otherwise.
Al-Taqwa College will soon be listed as an exposure site, joining a Coles in Yarraville that was listed as tier-two exposure site on Wednesday, the first in four days.
The state's new COVID-19 case came after Victoria recorded its first zero-case day since the fifth lockdown.