The lives of elderly people are being put at risk because of worryingly low uptake of flu vaccines among healthcare workers, public health experts have warned.

Key points: 180 flu outbreaks in NSW nursing homes since 2014

180 flu outbreaks in NSW nursing homes since 2014 Only 50 per cent of aged care workers get a flu jab

Only 50 per cent of aged care workers get a flu jab Health expert calls for flu shot to be compulsory

Up to 150 elderly people died during flu outbreaks in aged care homes in New South Wales in the past two years, although some of those may have died from other causes.

Nationally, 169 people of all ages have died from the flu in the past two years and the median age of those dying has risen sharply.

Experts are worried sick workers are inadvertently spreading illness during the flu season.

Professor Robert Booy from the National Centre for Immunisation Research and Surveillance wants the flu shot to be compulsory for people working in aged care homes.

Since 2014, there have been more than 180 flu outbreaks in aged care homes. ( ABC News: Alison Branley )

Healthcare workers must have other immunisations like Hepatitis B and Tuberculosis, but the flu shot is not mandated.

"It's the staff who can spread infection from one person to another," Professor Booy said.

"Each outbreak can lead to deaths, even the closure of a nursing home."

Since 2014, there have been more than 180 flu outbreaks in aged care homes in NSW alone.

While many residents in aged care homes get a flu shot, just one in two healthcare workers are vaccinated.

Across Australia, in 2015 the median age of people dying from the flu was 85.

This was a sharp increase on previous years. In 2013, for example, it was 63.

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Union not convinced of compulsory flu shot effectiveness

The nurses' union, the NSW Nurses and Midwives Association said while it supported flu shots, they should not be mandatory.

General secretary Brett Holmes said it should be free and accessible to workers unless they had a medical reason not to have it.

"We are not yet convinced that making it compulsory is the most successful way of preventing influenza outbreaks," he said.

"It can also be introduced by relatives or friends of residents."

Mr Holmes said sticking to hygiene standards and taking sick leave if staff were ill were better approaches.

NSW Health director of communicable diseases Vicki Sheppeard said while they encouraged flu shots among workers, aged care workers were a Federal Government responsibility.

"It's certainly something that we're considering in NSW but part of it is a logistical issue — having a mandatory annual vaccination can be very difficult to record and verify," she said.

"But in New South Wales, we make available free flu vaccine for all staff every year and strongly encourage all staff to have annual flu vaccine."

An issue between the workforce and employer: Health Minister

Federal Health Minister Sussan Ley, who is also responsible for aged care, said it was an issue between the workforce and employers.

"But I certainly strongly support those employers making it easy for their workforce to get the flu shot," she said.

The flu shot is free for the elderly, pregnant women, some Indigenous groups and people with chronic illness.

In 2015, 4.36 million doses of the flu vaccine were distributed in Australia under the National Immunisation Program and that figure is expected to rise to 4.48 million in 2016.

All up about 7 million flu vaccines are produced each year, meaning about 30 per cent of the population gets vaccinated.