Free flu vaccinations are being made available in Melbourne and Sydney as experts worry that winter might be a bad season for the virus.

Free flu shots are being offered in Melbourne and Sydney as experts worry about a bad season ahead.

Anyone not in the queue for a COVID-19 vaccine is being urged to have their flu jab as soon as possible.

The Immunisation Coalition is running free clinics at the Melbourne and Sydney town halls on Friday.

Professor Peter Doherty will have his flu shot at the Melbourne clinic to help publicise the immunisation drive.

There are concerns about a "rebound" flu season, based on 2017 and 2019 numbers being significantly higher than the previous year.

"It is unrealistic to expect that life will return to normal this year," said Mary-Louise McLaws from the World Health Organisation.

"While we have almost no COVID-19 local transmissions and with COVID vaccines being rolled out Australians are still at risk of influenza."

Earlier this month, the Royal Australian College of General Practitioners recommended all people over six months of age have their annual influenza vaccination.

The RACGP urged people in later phases of the COVID vaccine rollout to get their flu shot as soon as it was available, and then get their COVID vaccine.

The flu and COVID vaccines should be administered at least 14 days apart, according to clinical advice.