Rising flu and COVID-19 cases are placing the nation's hospitals under significant strain, according to the chief medical officer.

Paul Kelly said winter had brought significant challenges for the health system, as experts warn new COVID-19 variants will lead to higher levels of infection, even among people who have previously had the illness.

"It's certainly a strain at the moment from flu and COVID, a double whammy if you like," he told the Nine Network on Friday.

"(It's) also absenteeism of staff who are also being affected, so that's the challenge at the moment, as we often see in winter with flu, but having flu and COVID around does do that."

It comes as several states look to ease vaccine mandate requirements for workers in some industries.

Queenslanders will no longer need to be vaccinated to work in schools, childcare centres, prisons and airports, with changes coming into effect from Thursday.

Unvaccinated teachers in NSW could be allowed back in the classroom from next month.

Victoria will lift some of its restrictions at midnight on Friday, with positive cases from Saturday able to drive a household member to or from education or work without leaving their vehicle.

Mandates for third vaccine doses in the state will also be lifted for workers in education, food distribution and quarantine settings, with vaccine policies up to individual workplaces.

With case numbers continuing to rise, Professor Kelly urged for people to get their COVID-19 booster doses, along with the flu vaccine.

"The flu vaccine (is) very important now, and right across Australia, that's been made free for most people, but particularly those who are vulnerable of severe flu," he said.

"That includes young kids, actually. That's a difference to the COVID message. We need to increase that flu shot as well."

Only 70 per cent of the eligible population have received their booster for COVID-19.

Prof Kelly also said oral medications for COVID-19 would be a key consideration going forward as the country deals with the winter surge of infections.

"It's not an alternative for vaccination, vaccination is still the most important thing to make sure you're up to date on that," he said, particularly for older people and those with chronic diseases or immune suppression.

LATEST 24-HOUR COVID-19 DATA:

NSW: 9136 cases, 14 deaths, 1455 in hospital with 54 in ICU

Victoria: 7723 cases, 20 deaths, 412 in hospital with 27 in ICU

Tasmania: 1018 cases, one death, 47 in hospital with three in ICU

NT: 248 cases, no deaths, 13 in hospital with none in ICU

Queensland: 4520 new cases, six deaths, 522 in hospital with seven in ICU

ACT: 1038 new cases, no deaths, 99 in hospital, one in ICU

WA: 4749 cases, one death, 239 in hospital with eight in ICU

SA: 2311 cases, four deaths, 200 in hospital with 10 in ICU