The island state reported 552 new virus cases on Friday, a drop from 24 hours earlier and no additional deaths.

Tasmanians have been warned to expect a rise in infections, after some 60,000 public school kids started term one on Wednesday.

Deputy Public Health Director Julie Graham said there were three outbreaks at independent schools.

"Those are related to class groups. One in particular is actually related to events that occurred before students went back to school," she told reporters.

An outbreak in a classroom setting is defined as five or more cases in staff or students in the space of a week.

Tasmania has not adopted surveillance virus testing, as is the case in NSW and Victoria, with students advised to take a rapid antigen test when symptomatic.

Premier Peter Gutwein, meanwhile, urged Tasmanians to get a booster shot following new advice from the Australian Technical Advisory Group on Immunisation.

The advisory group on Thursday night said Australians will need a booster shot to be considered "up to date" with their COVID-19 vaccinations.

Mr Gutwein said aged care workers in Tasmania would be required to have a booster shot under an existing vaccine mandate.

He said he would seek public health advice about whether to mandate boosters for international tourist arrivals.

Public health would also provide advice on whether to make the booster shot compulsory in early childhood, disability and healthcare settings, where mandates were already in place, he said.

Thirteen people are being treated for COVID-19 in hospital, a rise from 11 reported on Thursday. One of them is in intensive care on a ventilator.

Three virus cases are in hospital for unrelated medical conditions.

The 552 fresh infections are a fall from the 637 reported on Thursday. There are 3295 documented active infections statewide, an increase of 60.

Tasmania has reported 10 virus deaths since reopening its borders in mid-December and 23 since the beginning of the pandemic.

Australian Associated Press