ACT health authorities won't say how many people have died, citing small numbers and the risk of identifying people. But acting chief health officer Kerryn Coleman said the number was fewer than five.

It comes as new figures from ACT Health have revealed the number of people diagnosed with influenza during the first four months of 2019 has more than doubled compared to the same period last year.

Between January 1 and May 10, there have been 310 confirmed influenza cases in the ACT, compared to 123 in the same four-month period in 2018.

This year's figure represents a five-year high for flu cases in the first four months of the year.

Dr Coleman said while the number of flu cases was up this year, the number of deaths had remained stable.

"The ACT Health Directorate has received reports of less than five influenza-associated deaths," Dr Coleman said.

"Due to this small number and the potential to identify the person or family affected, a specific number is not able to be provided."

Pharmacy Guild of Australia ACT branch president Simon Blacker said some pharmacies had already given more than the number of vaccinations they gave for all of last season.

He said the flu season appeared to have started earlier than usual in the summer months.

Mr Blacker said the current demand suggested pharmacies would likely face a shortage of supply later in the season.

"I would suggest to patients don't waste time, now's the time to speak to pharmacies and GPs and have a vaccination," he said.

"What we're seeing is strong demand for the flu vaccine which is really positive for herd immunity, probably from increased awareness in the community.

"Pharmacies have had vaccines in stock since about late March and our experience even today is there is still strong demand.

"I'm aware of pharmacies halfway through their vaccinations and already exceeding last year's vaccination numbers."

The beginning of this year's flu season has been a deadly one, with 26 deaths reported in Victoria, including three children.

The flu has also led to the deaths of 25 people in Queensland and 27 in South Australia.

Last year saw the lowest number of flu cases recorded in Canberra in five years, with 476, compared to more than 3000 during 2017.

Between 2014 and 2016, the number of flu cases was between 1200 and 1600 per year.

Dr Coleman said more flu vaccines had been distributed in the ACT this year compared to 2018, despite fewer children receiving vaccinations.

"To May 13, 2019, 75,560 doses have been distributed. This is higher than the recorded 70,677 doses distributed in the same period in 2018," she said.

"However, there are indications of a slower uptake in the number of kids under five receiving the flu jab this year."

Data on the number of people who have received the vaccine won't be known until early next year.

Dr Coleman urged Canberrans to get vaccinated for influenza ahead of the flu season.

"ACT Health is urging all parents who have children aged from six months of age to under five years to book their child with their usual immunisation provider in to get a free flu shot now," she said.

"The best thing people can do is get vaccinated. If you get sick, stay home and remember to wash your hands, cover your coughs and sneezes and put used tissues in the bin straight after use."

The ACT government has also rolled out a pilot program for this year's flu season, with some Canberra pharmacies supplying government-funded vaccines to people over 65.