The figure has grown since late June, as the BA.4 and BA.5 strains became dominant since they can evade immune protection, whether from vaccination or prior infection, while some experts say the latter can be as infectious as measles

The number of those in hospitals is the highest since the emergence of the coronavirus, exceeding January's high of 5,390 during the first wave of Omicron infections. Daily death tolls have also risen, topping 100 on Saturday for the first time.

More than 1,000 retirement homes have suffered outbreaks, the government said, as the elderly are largely affected.

With several aged care centers battling a shortage of staff, the support of defense personnel in such facilities is to be extended until the end of September, Defense Minister Richard Marles said.

"It is an extreme measure and it's right to describe it as that," he told ABC television. "Given the number of outbreaks that we've got right now, this is the right thing to do."

Many frontline workers in hospitals are also sick or in isolation, worsening the healthcare crisis.  

During a harsh winter with both COVID-19 and the flu virus circulating, authorities have recommended the use of masks indoors and urgent booster doses of vaccine, while telling businesses to allow work from home.

Australia, one of the countries most heavily vaccinated against COVID-19, has given two doses to about 95 percent of those older than 16, although just about 71 percent have had booster shots.

Still, its tally of about 9.13 million infections and 11,181 deaths was lower than many developed economies.

Meanwhile, New Zealand Prime Minister Jacinda Ardern said on Monday that there were early signs that new COVID-19 cases were falling, even as hospitalizations jumped to their highest level since March.

New Zealand recorded 6,910 new COVID-19 cases on Monday, well below average levels over the past week, according to data from the Health Ministry.

However, the number of people in hospitals with COVID-19 jumped to 836, the most since March 29 when 842 COVID-19 patients were in hospitals.

Ardern told a weekly news conference that authorities had seen a drop in the prevalence of COVID-19 in wastewater, which suggested there might be a further decline in cases.

"Even when case numbers come away, it takes us about two weeks to see that really shift our hospitalizations," she said, adding that it was, therefore, important to watch hospitalization numbers in coming days.

New Zealand closed its border in early 2020 as the coronavirus was spreading around the world and imposed lockdowns and strict social distancing to keep its infection low.

The COVID-19 death toll in the country of 5.1 million people is 2,006.

It began reopening its border in February and will lift the last restrictions at the end of this month.

The Omicron BA.5 sub-variant is driving New Zealand's infections with 59,445 active cases in the past seven days, although authorities say many infections are unreported.

Ardern said there was also some suggestion that cases might have been underreported during the recent school holidays.