Why this year’s flu is so deadly
IT'S a Flunami.
Confirmed flu cases in Queensland for 2019 have surpassed 25000, about five times the five-year average at this time of year.
If the trajectory continues, 2019 will top the record 2017 year for Queensland flu diagnoses of 56,591.
Already, figures provided by Queensland Health show at least 51 influenza-associated deaths in 2019, the youngest in their twenties and thirties. That's eight more flu deaths than the 43 recorded for the whole of 2018.
But the smaller numbers of flu-related deaths last year occurred against a backdrop of lower than usual recorded influenza cases in Queensland, with 15,698 - more than 9000 fewer than notifications so far in 2019. Numbers are expected to climb steeply in the next two months as the peak of the flu season hits.
Although hospitals have been strained with flu cases turning up in emergency departments this year, University of Queensland virologist Ian Mackay blamed the sheer weight of numbers, rather than exceptionally severe flu cases.
Associate Professor Mackay said the unprecedented numbers of laboratory confirmed cases in the first half of 2019 had occurred in conjunction with a highly unusual Summer flu season that had also been seen in New Zealand, South America and South Africa.
He said the reason for the high numbers of Summer flu cases in the Southern Hemisphere this year - what he described as an "early flu storm" - were a medical mystery. The last mammoth Summer flu season in Australia was more than two decades ago in 1995.
Associate Professor Mackay said while the predominant flu strain in Australia this year was H3N2, in South America, it was H1N1.
He said World Health Organisation laboratory tests suggested the quadrivalent flu vaccine was not perfectly matched to protect against the predominant flu viruses infecting Australians this year, particularly the H3N2 and the B Victoria strains.
But he still strenuously advised Queenslanders to get an annual flu jab if they had not yet done so.
"The vaccine is the only thing we have that will protect us against flu," Professor Mackay said.
With the amount of flu circulating this season, he said people were at risk of being infected with more than one strain of the virus.
"That's why they put four different virus types in the vaccine to try and prevent people from getting not just one flu, but maybe two or three different flu infections, in a season," Professor Mackay said.
He's called for more detailed genetic testing of circulating viruses to understand why flu numbers have been so high, so early, this year leading to bigger numbers of influenza-associated deaths in the first half of the year than usual.
"It may be that we find something that's caused flu viruses to be different this year that's allowing them to transmit earlier," Professor Mackay said. "We don't know because we're not doing that work. We need a detailed study to try and crack that."