Cynthia Kerr was asleep in bed one night when her smartwatch woke her with a warning her heart rate was extremely high.

Key points: The WHO centre on influenza said Victoria's reporting of flu cases was a 'piecemeal analysis' and the true figures are much worse

The WHO centre on influenza said Victoria's reporting of flu cases was a 'piecemeal analysis' and the true figures are much worse Having a more accurate picture of flu would help people take the virus more seriously

Having a more accurate picture of flu would help people take the virus more seriously Aged care homes are not required to report outbreaks which would give a more accurate picture of the problem

The next day Ms Kerr, from Wallan, north of Melbourne, had a raging fever and her chest started to become congested, a danger sign for someone with asthma.

"My fever at home was over 40 degrees Celsius and I was aching everywhere. So I knew right away I had flu symptoms. I started to get chesty, headache, dry cough, body aches," she said.

"I actually thought I was going to die. It sounds dramatic but with my temperature so high and with the way my chest felt and my age.

"Not that I'm old old but I'm thinking flu has been known to take people my age so I was pretty scared."

She was eventually diagnosed with influenza A and spent four days in hospital.

Ms Kerr's experience is not unique.

Cynthia Kerr thought she was going to die when she got sick with influenza A. ( Supplied )

In 2019 the number of flu cases is three to four times higher than normal.

There have been over 13,000 confirmed cases of the flu and 26 deaths in Victoria, but the World Health Organisation said those figures severely under-represented the true extent of the problem.

The deputy director of the WHO Collaborating Centre for Reference and Research on Influenza in Melbourne, Ian Barr, described the state's reporting process as "piecemeal analysis" and said the real figures are much worse.

"The 13,000 cases, [you] could easily multiply it by 10, no-one really knows," Professor Barr said.

He said the number of people who get tested are a fraction of those who are infected and the same is true for influenza-related deaths.

"Both of them are only tips of the iceberg guestimates," he said.

"There's no accurate figures on this but you can imagine something like only 10 per cent of people would bother going to the doctor and that doctor having a sample taken and having a result done."

Professor Barr said the number of deaths reported was also likely to be well below the actual death rate.

"Probably the best estimates you can get is looking at the deaths in the US that happen per year and dividing that by our population, so dividing their numbers by 10, something like that," he said.

"[In] the US, they estimate [there are] between 36,000 and 61,000 deaths per year from influenza.

"So if you divide that by 10 it probably gives you an idea of somewhere around the numbers who die of flu each year [in Australia]."

Victoria's reporting system

Health Department figures show 26 Victorians have died from influenza this year.

Three of the deceased were children while the rest were aged care residents.

The department receives reports from aged care facilities about outbreaks of influenza and deaths in those circumstances, but the homes don't have to report outbreaks — they're just encouraged to.

The number of people who get tested for influenza is just the tip of the iceberg, Professor Barr said. ( ABC News: Yara Murray-Atfield )

It also receives notifications of confirmed cases from pathology services but without any further clinical information so the data doesn't identify cases where someone has died.

Notifications of deaths do come from the coroner, but only after an autopsy reveals influenza as the cause of death or a contributing factor.

Experts predict that providing the public with a more accurate picture of the impact of flu would help people take the virus more seriously.

The Royal Melbourne Hospital's director of respiratory medicine, Lou Irving, said that could see vaccination rates increase.

"It'll encourage some people to get vaccinations, it'll encourage some people to stay away from work or not send their kids to school when they're sick and hence not spread it to other people," Dr Irving said.

"Understanding the disease will also encourage people to go see their GP when they do get sick so the influenza itself can be treated and in particular the complications of influenza, the secondary bacterial pneumonia, worsening of underlying disease can be managed.

"A lot of people, when they've got influenza, say I'll just take a day off at home or I'll battle through at work and all of that can have consequences."

Calls for flu testing all year around

The large numbers of flu cases this year is in part due to a strong summer flu and experts believe they should now test for flu all year round, not just in the traditional [winter] season.

Dr Irving said the Royal Melbourne Hospital was seeing more flu during the summer and it might be because they were doing more testing.

"But at the same time there is no doubt that we're seeing much, much more [influenza] in April [and] May than we've seen previous years," Dr Irving said.

"So we're seeing activity now that would be like the peak of a normal season in July or August."

Other hospitals such as the Alfred, Royal Melbourne and the Children's Hospital are set up to test all year around.

"I think we should continue to test throughout the year and record the data so that we've got a better understanding," he said.

"My feeling is although we are doing more testing I think it's equally possible that the virus and the nature of the flu seasons is changing in the same way that we've got a feeling that the seasons themselves, the weather itself is changing."