A record number of Australians are getting vaccinated against the flu, prompting one company to order an extra 400,000 shots to give to GPs and pharmacies.

An extra 400,000 doses of the flu shot are on their way to Australia to help meet a growing and unprecedented demand for the vaccine.

More than 12 million vaccines have already been distributed across the country - two-thirds of which are for people who are eligible for a free shot under national or state immunisation programs.

While supply for those programs - targeting the elderly, young children and pregnant - is secure, there has been "unprecedented demand" for flu vaccines through GPs and pharmacists.

Federal Health Minister Greg Hunt said he has been working with vaccine companies to ensure there is sufficient supply in the private market.

Pharmaceutical company Sanofi will bring a further 400,000 vaccines to Australia over the coming weeks, to be made available through GPs and community pharmacies.

"This will take the overall number of flu vaccines available in Australia this year to over 12.5 million - an increase from 11 million in 2018," Mr Hunt said in a statement on Wednesday.