A music festival held in Launceston last month has resulted in a "very significant" spread of COVID-19 with event goers contacted by Public Health to monitor their symptoms and use "common sense".
Twenty-five positive cases have been identified from Party in the Apocalypse on December 27 and 28 where about 5000 people attended on each day.
Public Health is using Check In TAS data to contact attendees, but there is no requirement for everybody to get tested.
Premier Peter Gutwein said people should only book a PCR test if they displayed symptoms.
"This does not mean that everybody that attended Party in the Apocalypse on those two days needs to turn up to a testing clinic or take a RAT test," he said.
"If you were at that event, you need to use your common sense to monitor for symptoms, and if symptomatic, please call the Public Health hotline and go and get a PCR test.
"It doesn't mean you need to line up today if you attended that event on either of those two days."
The event was held over two days at Churchill Park in Launceston.
Organisers outlined their COVID-safe measures, including a requirement for attendees to be double vaccinated and for the widespread use of masks.
Acting director of Public Health Scott McKeown said there was no reason why similar events could not go ahead in a COVID-safe environment, and that serious illness was yet to occur from the event.
"For at least 25 cases to be identified across those days, there's been very significant transmission that's occurred," he said.
"We're messaging out to people who have attended both of those days, we have already messaged earlier on when we identified cases that were associated with the first day.
"It's important that we understand, that events, we want them to operate safely, they operate with COVID-safe event frameworks in place.
"And any events that are organised over the Christmas-to-New Year period, where organisers have implemented COVID-safe plans ... certainly where transmission's occurred, such as in the Party in the Apocalypse, when we identify that, we do want to make sure that people are aware of that risk and follow the advice to monitor themselves closely for symptoms."
Tasmania recorded 466 new cases of COVID-19, as reported on Monday morning.