The surge in demand was expected, with health professionals strongly recommending people get the jab to avoid the potentially deadly combination of seasonal influenza and COVID19, and to avoid confusing the symptoms of the two viruses.

More than 3.57 million flu shots have been administered since March 1 this year, according to the Australian Immunisation Register.

In 2019, only 1.53 million had the jab by the end of April, while in 2018 that figure was 1.22 million.

To catered for the expected surge in demand, the government order an additional three million flu shots, bringing the total number of vaccines available to Australians to 16.5 million.

A Department of Health spokesperson said the number of vaccines provided through the National Immunisation Program (NIP) was based of the forecast demand from states and territories.

"Although it is too early to say how many vaccines may be required, record numbers of supplies have been secured and Australia is well placed to respond to any increased demand that may arise this year," the spokesperson said.

Some regional areas are already running low on flu shots, however the additional three million vaccines are expected to hit pharmacies this week.

Free government influenza vaccinations through the NIP are available for children aged between six-months and under five years, anyone over 65 years of age, all Aboriginal people from six months of age, and pregnant women.

Anyone between five and 65 with chronic health conditions, impaired immunity, factors predisposing to severe influenza, should consult with their GP.