SA Police is investigating if a woman who tested positive for COVID-19 and sparked the Northern Territory's lockdown had the relevant travel permits into South Australia from Victoria.
Northern Territory authorities revealed the 21-year-old woman, who tested positive to COVID-19 on Friday night, was the primary infection case in the outbreak.
The woman is understood to have travelled from Cairns to Adelaide, before driving to Melbourne on October 21, and back again on October 24.
Travel is not allowed from Victoria to South Australia without a 14-day quarantine, apart from for essential workers and people living within 70 kilometres of the border.
"SAPOL are aware of [the] allegation the female entered South Australia from Victoria illegally and the matter is under investigation," a police spokeswoman said.
SA Health said it was still investigating whether she was infectious while in South Australia, although it said that was unlikely.
"At this stage, we have no further details on this case," a spokeswoman for the department said.
It has not named any exposure sites connected with the woman.
Vaccine deadline for healthcare workers
From today, most South Australian healthcare workers need to have received at least one COVID-19 vaccine.
The direction comes into effect a week after the deadline for hospital workers.
Today's deadline applies to those working at GP, specialist and dental clinics, pharmacies, private pathology centres, radiology clinics, blood donation centres, Aboriginal health centres and allied health facilities.
South Australia reached a 70 per cent vaccination rate for people aged 16 and over yesterday.
About 84 per cent of the state's residents have had at least one COVID-19 vaccine dose.
The state has had no known active cases in five days.
