The Brisbane Youth Detention Centre at Wacol will be in lockdown for weeks after the Ipswich woman worked five shifts after coming down with symptoms on August 8.

Health authorities are testing 127 detainees – some as young as 13 – and up to 520 staff, not knowing if there is already a cluster.

Visits, transfers, court appearances and even education classes have been cancelled, and a large-scale contact tracing exercise is under way to determine where the woman may have been infected and where she could have infected others.

Premier Annastacia Palaszczuk today expressed frustration that people still failed to heed the warnings about COVID-19, saying it was “a story of a woman who was sick and still went to work”.

“If you are sick, stay at home and get tested,” Palaszczuk said.

A second puzzling case – also with the potential to become a cluster – came after a woman had followed all the rules. She had flown from Japan to care for her sick father in Brisbane, only to test positive on her return a month later.

The woman arrived in Sydney on July 18, stayed in hotel quarantine where she twice tested negative, flew to Brisbane on August 1 and then back to Sydney on August 17, and on to Japan on August 18. It was only on arrival into Tokyo, where she was required to undergo a compulsory COVID-19 test, that she tested positive.

The woman spent most of her time in the Morningside and Bulimba areas and also had Sunday brunch at the Jam Pantry café in Greenslopes on August 16, where six potential contacts have now been identified and tested. Those results are expected later on Thursday.

Chief Health Officer Dr Jeannette Young said it was not clear whether the woman had COVID-19 while in quarantine, during her stay in Brisbane, or had possibly contracted it on one of her flights.

“We’re not sure where she acquired the infection but we believe the risk (to Queensland) is very low,” Young said, noting that the woman had not been very active in Brisbane.

Deputy Premier and Health Minister Steven Miles said it was important for authorities to respond to the case as if it had the potential to become a cluster.

The case has not been added to Queensland’s tally because the woman is in Japan. However, the number of active cases in Queensland has still risen by two to eight, with the new Ipswich-Wacol case and another person who acquired COVID-19 interstate being readmitted to hospital.

Queensland’s troubling day came as Victoria, still Australia’s worst-hit state, recorded another 240 new cases and 13 more deaths.

NSW has recorded five new cases: two in hotel quarantine, and three in southwest Sydney.

Young said contact-tracing for the youth detention worker had yet to identify any link to the recent Logan cluster of five cases. That cluster, however, had prompted the centre to ban visitors from July 27, which will limit the number of potential exposures.

Department of Youth Justice director-general Bob Gee said the centre had prepared for COVID-19 and dealt with infection risks before. Staff and detainees have been given personal protective equipment.

“Last night all of the young people were locked in their rooms and they stayed there,” Gee said.

Young reiterated the need for Queenslanders to practice social distancing, good personal hygiene, stay home and get tested if sick, and avoid travelling to problem areas.

“We don’t know when our next case might appear in our community,” Young said.

“We don’t know where these cases might end up.”

Queensland Health has yet to release a list of places visited by the detention centre worker. A public health alert has been issued for Virgin flight VA962 from Brisbane to Sydney on August 17 and anyone who dined at The Jam Pantry on August 16.