Chief Minister Michael Gunner said today the virus had been circulating in the town for at least nine days with no cases before the second cluster emerged.

Two new positive cases in Katherine were announced on Friday, bringing to 25 the confirmed cases in the cluster, which has been linked to a previous cluster from a 21-year-old Cairns woman.

Among the new cases is non-Aboriginal man, aged 39, who is the first health worker in the Territory to test positive after working with a close contact case.

A woman, 59, who tested positive took a test because she had symptoms but had not previously been identified as a contact.

A positive wastewater finding for COVID in the Binjari Aboriginal community on the outskirts Katherine had lead to a rapid response team being sent in with mobile testing sites mass testing in the 200-strong community today.

Mr Gunner said it remained a mystery how the second cluster emerged after the gap without cases.

COVID-19 NEWS

"There is a very real possibility that there are people in Katherine who have COVID and either don't know it or who don't want to know and those people then spread it in the community," he said.

"Best case scenario, we got lucky and it hasn't spread any further than what we have caught so far.

"Worst case scenario, this has been silently spreading for a week and we are a day or two away from a disaster.

"The only way to get to the bottom of this is by testing the hell out of the Katherine community."

While testing lines remained long, they "needed to be longer" and anybody with the mildest of symptoms needed to get tested. These included fever. chills, cough, a sore throat, tiredness, difficulty breathing, nausea and vomitting, headaches, muscle or joint pain, a loss of smell or taste, a runny or blocked nose.

"Even if you think it's not serious. Even if you think you're being ridiculous ... get tested," Mr Gunner said.

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Anybody in Katherine who has previously tested negative after having been at a contact site has been asked to get retested as the Delta strain could present "a few days later".

Mr Gunner said that the Katherine community was doing it right but had to "keep going".

Howevert the vaccination rate in Katherine continued to be below where authorities needed it to be.

"There were over 98 new doses administered in health clinics yesterday," Mr Gunner said.

"And about half of those were first doses. It's just not good enough.

"It does not make public health sense to end lockdown if we think there's still COVID in the community and the community is not adequately vaccinated."

The priority for Friday in Katherine was testing and vaccinations.

"For the people of Katherine there is one clear message today. A COVID vaccine is your ticket to freedom," he said.

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