The new case is a household contact of the contract worker and has been transferred to the Howard Springs quarantine facility.
Northern Territory Chief Minister Michael Gunner said there are five household contacts of the contract worker in Katherine.
Mr Gunner also said there are three household contacts in Humptydoo who are all being tested.
Deputy Chief Health Officer Charles Pain said investigations into the source of the community transmission are continuing.
“We still don’t know where he got it from,” Dr Pain said.
Mr Gunner said the contract worker had spent time with a person who had recently arrived from Cairns on Friday and Saturday night, authorities are investigating this link.
“We are interviewing them to determine whether this could be the source,” Mr Gunner said.
Popular club possible exposure site
Mr Gunner said there is “heavy contact tracing” underway following the region’s first cases of community transmission in months.
At least 53 close contacts of the man have been identified at the Katherine Club.
The Monsoons Club in Darwin has been classified as an exposure site.
A positive case attended the venue on Friday 29.
But Chief Minister Gunner said “given the amount of people at Monsoon, and given this large exposure period”, this could be where the virus has transmitted.
The Mantra Pandanas in Darwin was also flagged as an exposure site after a positive case stayed there on Friday and Saturday night.
The Tindal RAAF base is no longer being considered as an exposure site.
Mr Gunner said the Katherine Woolworths on Monday November 1 between 6.30pm and 6.50pm and the Puma service station in Katherine Tuesday November 2 6.17am and 6.25am are now classified as casual contact sites.
At midnight last night, greater Katherine entered a 72-hour snap lockdown after a community case of COVID-19 was detected.
In greater Darwin, the Northern Territory government declared a “lockout” for the same period, stopping all movement in and out of the capital and imposing lockdown conditions only on the city’s unvaccinated residents.
Everyone living in either region must wear a mask when leaving the house, regardless of vaccination status.
Health authorities remain extremely concerned about the cases.
“We still have a few days to go before we can consider what we can do next,” Dr Pain said.
Dr Pain said if testing rates and vaccinations rates continue to remain high then he is confident the territory will get out of lockdown.