An extra one million Australians - potentially including those with diabetes, severe asthma, heart disease and other medical conditions - will be able to get the vaccine for free from next winter if it is approved by the federal cabinet.
Under the current scheme, only people aged over 65 and indigenous people over 50 do not have to pay for the jab.
Flu specialists have welcomed the recommendation by the Therapeutic Goods Administration's pharmaceutical benefits advisory committee in response to a submission by the government's expert immunisation advisory group, ATAGI.
"This is definitely a good move to try to attract more vaccinations among a group of vulnerable people," said Dr Alan Hampson, chair of the Influenza Specialist Group.
"Many of these people were slipping through so hopefully this will boost numbers up and send a message that it's very important to get immunised."
Dr Ian Barr, deputy director of the WHO Collaborating Centre for Reference and Research on Influenza in Melbourne, said the move was a "step in the right direction".
"It's more convenient for people to be able to walk straight into a doctor's surgery and get immunised and any hurdles we can remove to encourage immunisation, the better."
The recommendation, which needs to be signed off by the cabinet, does not define who will be included among the high risk, but it is expected to include people with chronic conditions like diabetes, cardiac disease, severe asthma, emphysema, HIV and neurological conditions.
Indigenous people aged over 15, homeless people and women who are pregnant during the flu season may also be included.
Meanwhile, the current flu season is at its peak, with an increase in diagnosed influenza and influenza-type illness in August.
"The number of cases have increased as expected but it is still relatively mild compared with previous years," Dr Barr said.
Six children died from influenza last year and more people were infected with the virus than any other season for the past decade.
