Australians are ageing and coming down with more vaccine-preventable diseases meaning the public health system is under increased pressure, a report says.

Australia's ageing population is driving up hospitalisation rates while health practitioners are witnessing a dramatic rise in vaccine-preventable influenza cases in hospitals.

The latest Admitted Patient Care 2017-18 report, released on Thursday, showed 60 per cent of the 11.3 million admissions to hospital in 2017-18 were to the public system.

Publicly funded admissions, over the last five years, have grown at 4.7 per cent per year on average while admissions paid by private insurance grew at an average of 3.6 per cent per year.

The total number of hospital visits grew by about 3.8 per cent each year over that period.

The Australian Institute of Health and Welfare report says older Australians were a "key driver" of the growth.

It's true that the total number of Australians 65 and older is increasing but those older age groups are also going to hospital at a higher rate.

"This increase was at a faster rate than population growth (in Australians older than 65)," AIHW spokesman Adrian Webster said in a statement.

People aged 65 and older, who make up about 15 per cent of Australia's population, account for almost half of all patient days.

But the report also shows Australians are falling prey to unnecessary maladies.

Over just two years, 2016-17 and 2017-18, vaccine-preventable hospitalisations rose by almost 47 per cent.

'This reflects large numbers of admissions for influenza and pneumonia in most states and territories,' Dr Webster said.

Elective surgery waiting times have increased for both public and private patients in public hospitals, the report also found.

The median wait time for elective surgery in public hospitals in 2017-2018 was 41 days overall over the last year.

Public patients waited an extra three days compared with 2013-2014, and private insurance patients waited an extra two days.

Aboriginal and Torres Strait Islander were hospitalised at 2.6 times the rate for other Australians.