A casual receptionist who worked next to the COVID-19 ward at a Brisbane hospital and holidayed at Magnetic Island has tested positive to the virus, triggering a three-day lockdown of 4.5 million people in south-east and north Queensland.

Queensland Health authorities on Tuesday scrambled to track down potential contacts of the woman and her family at a long list of exposure sites in Brisbane and Townsville, amid fears the case could mark the first spread of the virus in regional Queensland.