Genomic testing has confirmed the Northern Territory's current COVID-19 outbreak was triggered by an infected woman who illegally entered the Top End last month.
The 21-year-old lied on her border entry form before travelling from Cairns to Darwin after visiting Victoria, where she contracted the virus.
She infected a man she spent two nights with in Darwin as the virus spread to two others in Katherine before authorities declared they had control of the outbreak on November 9.
But that was short-lived with the same strain of virus now found to be responsible for the current cluster, which has grown to 19 cases since Monday.
All those infected are Indigenous Territorians.
It started when a 30-year-old woman and a 43-year-old man from Katherine, 320km south of Darwin, were reported to be infected.
The woman was unvaccinated and travelled from Katherine to Robinson River - 1000km southeast of Darwin - where she tested positive, the first case reported in a remote NT Aboriginal community.
Nine new cases were detected in Katherine on Tuesday, including a 71-year-old man and a 65-year-old woman who was admitted to Royal Darwin Hospital.
Eight new cases were reported on Wednesday, with five infections diagnosed in Robinson River, including a three-week-old girl.
No new cases were recorded on Thursday but Chief Minister Michael Gunner warned the crisis is not over.
"This is good news, but it is not a day to get ahead of ourselves," he told reporters.
He said people should not assume the outbreak is under control and the virus trapped.
"This is Delta, it's in large vulnerable households. We're not out of the woods," he said.
Health teams will concentrate on finding the missing links between the two clusters, with NT Health saying it now knows the virus was circulating in Katherine from November 4 to 13.
They've identified 384 close contacts, with 288 contacted and isolating, and 201 returning negative tests.
All 350 residents at Robinson River have been tested but many results won't be available until later in the week.
About 50 people from the community have been transferred into quarantine at the National Centre for Resilience.
Greater Katherine and Robinson River were plunged into a three-day lockdown when the first cases were announced on Monday.
That has since been extended to seven days, with a territory-wide order to wear face masks in most public areas.
