ACT Health reported no deaths on Sunday, but the number of people in intensive care increased by one to six patients.

There were two people receiving ventilation support with COVID-19, the same number as the previous day.

ACT Health announced on Wednesday a man in his 70s and a woman in her 90s died with the virus. A man in his 90s also passed away this week.

There were 1001 new cases reported on Saturday, while there were 71 people in hospital with the virus.

The infections reported on Sunday were the smallest number since May 9, however there is often a drop at the weekend as testing numbers decline.

There were 6366 active cases in the territory on Friday night and 6472 active cases on Saturday night, figures from ACT Health showed.

The highest caseload for Canberra was reported on January 19, this year, at the height of the initial Omicron wave when there were 6655 active infections.

Third-dose vaccination rates have continued to stay stagnant, amid warnings people are at greater risk from serious illness and death if they have not had their third shot.

Of the population aged 16 and over, 75.8 per cent have had three doses. Among the population aged 5 and up, 97.1 per cent have had two doses.

The Australian Technical Advisory Group on Immunisation is still examining the evidence on whether a fourth dose of a COVID-19 vaccine will be needed for at-risk groups for winter.

A UK trial that involved 166 people with an average age of 61 found a fourth dose seven months after a third COVID shot enhanced protection "above and beyond" the third-dose vaccination.

The results, published in The Lancet medical journal, showed a fourth dose boosted anti-body levels above the levels achieved by a third dose.

Meanwhile, more than 500 people have reported having COVID more than once to ACT health authorities, the latest epidemiological report for the territory said.

But officials were quick to caution on Friday that this may not necessarily be a reinfection but rather a "second episode" of COVID-19. Officials say measuring reinfections is difficult.

The BA.5 subvariant of COVID-19 has also been detected in Canberra for the first time, in a sample collected from a recently returned overseas traveller.

The latest weekly report from ACT Health, which covers the week from May 2 to May 8, said 508 individuals had reported more than one episode of COVID-19 since March 2020.

The report said less than half - 45 per cent - had their first positive test in December 2021 or later.

"Currently, there is no national agreed case definition for a reinfection of COVID-19," the report said.

Victoria reported 10,197 new cases of COVID-19 on Sunday, along with 10 deaths and slight increases in the number of patients in hospital and in intensive care units.

There are 528 COVID-positive patients in Victorian hospitals, an increase of four patients from the previous day, along with 27 people in intensive care.

NSW reported 9036 cases of COVID-19 on Sunday and four deaths.

The number of people hospitalised in the state - 1377 - remained flat, although the number of people in intensive care rose by one to 59.

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