Flu season which struck down 310,000 Australians 'worst on record' due to early outbreaks - ABC News

Researchers are warning little can be done to prevent future severe flu seasons, if a pattern of prolonged, year-round outbreaks continue.

Key points:

• More than 310,000 people presented to Australian health services with influenza in 2019, marking the country's worst flu season on record
• Researchers say that it was one of the most successful vaccination years to date but early outbreaks occurred before vaccines were given out
• With continued early outbreaks, 2020 could be similar

Last year, Australia experienced its worst flu season on record, with more than 310,000 people presenting to hospital and health services nationwide.

The figure is seven times greater than Australia's previous 18-year average.

'Happens once every 10 years'

World Health Organisation (WHO) influenza researcher, Ian Barr, said such aggressive seasons were generally a "one-in-every-10-year occurrence", but early flu outbreaks had seen Australia go through two in just three years.

He said it is an issue that is hard to predict and one difficult to address with vaccines.

"Definitely in terms of influenza seasons 2019 was the biggest Australia has had … it was very unusual," Dr Barr said.

"I think one of the big reasons it was a such a severe season was that in most states, it was very prolonged.

"In Queensland it was reasonably long, but then in Victoria, Tasmania and, to a lesser extent, New South Wales, it was a very prolonged season which started much earlier than we would normally expect to see such high intensity activity.

"It lasted right through 'til October."

According to Dr Barr, last year's peak occurred almost two months earlier than normal and researchers have found it difficult to determine the cause.

He believes international travellers played a significant role, but said other factors were also at play.

"The whole business of influenza is a numbers game, so if you get enough people coming back to Australia with infections from overseas, that can happen," Dr Barr said.

"We put it down to higher tourist numbers, more Australians travelling overseas, climate conditions.

"But we actually believe that a number of last year's cases originated from some of the large outbreaks in the Northern Territory, which led to small outbreaks in the southern states — Queensland included.

"It's most likely a combination of those factors … which is just plain unlucky."

Hospital beds full and staff sick

Queensland Health Minister, Stephen Miles, said the intense season put a major strain on hospital and health services nationwide, which would have to incorporate early outbreaks into future planning.

"Certainly the levels we saw, it took a very high toll on the community and the health system," he said.

"We had a record number of summer cases and that elongated the impact on our hospitals through more months of the year, as well as many of our own staff ended up catching the flu.

"That itself has an impact on our ability to cover rosters and increase staffing when we really need to, it makes the job of running hospitals even harder."

According to Mr Miles, early preparation had aimed to deal with influxes in patients, but not for seasons which extend for nearly half the year.

"Every year we have a winter bed strategy that's designed to deal with that, but the peak last year we had to bring it forward substantially," he said.

"There's a lot of mysteries still about the flu and that's why we have a lot of people allocated to researching and working on it.

"Every year the virus is different and the way it impacts us is different, we do our best to predict it.

"It just demonstrates how serious a virus the flu is and how important it is to get vaccinated and stop it spreading even more."

But WHO's Dr Barr said he does not believe vaccinations would have much impact where early outbreaks of influenza are concerned, stating 2019 was one of their most successful vaccination years to date.

"I wouldn't say the vaccine had too much of an impact on that [severe season last year], the season was already in the starter gates and running before most vaccines were even given out," he said.

"Given the significant number of cases in March and April — the vaccine isn't even available during that time, and it normally takes a couple of weeks after being vaccinated to reach peak immunity.

"I wouldn't say this was a vaccine issue."

Longer lasting vaccines a long term solution

According to Dr Barr, vaccines are created based on strains circulating in the northern hemisphere, which meant it would be difficult to bring forward a release date in Australia.

He said current vaccines only last three to six months, so early immunisation would also mean they may not last through the peak months of July and August.

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"You could bring it forward slightly and make some vaccines available a bit earlier, but early to late March, that's really about the best you could do," he said.

"If we could have some early vaccines available, especially in certain states, it may help out slightly.

"But perhaps there's also some learning opportunities in terms of having longer lasting vaccines, we're always trying to be better.

"There's a lot of work and money being invested in trying to improve influenza vaccines, we're taking a number of different approaches, but these things take time."

While 2019 saw the highest number of influenza cases across the country, 2017 still holds the record for the highest number of flu-related deaths, with over 1,100 cases.

Last year there were over 900 influenza linked deaths in Australia.