Peter Collins set out to receive his influenza vaccine on Wednesday when he discovered a number of clinics and pharmacies had run out of the vaccine.

"First I went to the WRAD clinic and discovered they had none and was advised to go to a pharmacy, so I went to (one) and they had run out," he said.

"Eventually we found some at Northpoint and even they said they were on their last few doses.

"I was surprised that there was such a shortage considering the vaccination has been given so much publicity by the government urging people to have their shots."

Direct Chemist Outlet pharmacist Kelly Tong said stock has been exhausted without any indication of when it will be replenished.

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"We are seeing that with the number of influenza cases in the news and also general public interest into vaccines, numbers are a lot stronger this year," she said.

"We have almost run out of stock and we haven't been able to secure any more stock until possibly next week.

"Patients from all walks of life have been sent to us from the medical clinics because they have run out. No-one's got any."

There are two types of vaccine stocks, Ms Tong added.

"There's the private stock that we buy from wholesalers and then on-charge to patients, then there's the other set of stock which is the national immunisation program stock from the Health Department.

"We still have some of that stock, but there's a criteria for those, so if you're a fit and healthy young person you can't use that stock.

"The privatised stock is running out."

Flu vaccines are becoming less available for private customers due to the government purchasing available stocks from the private market.

Pharmaceutical company GlaxoSmithKline has announced that its Fluarix Tetra seasonal influenza immunisation is no longer available in the private market, with all stocks diverted to supply government programs.

"GSK has received urgent requests from governments for additional doses, particularly for the vaccination of children under five years of age," the company said.

"Consequently GSK has taken the decision to divert all of its remaining Fluarix Tetra vaccine doses to these important programs."

Ms Tong said the other two brands Afluria Quad and Fluquadri are also currently out of stock from the pharmacy's wholesalers.

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.

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