“It will be some months before we can make a comparison of this year with pre-pandemic flu season, but anecdotally speaking, all we are hearing is that people are getting really, really sick with the flu, and it appears more so than previous years,” Munoz said.
“It makes sense given we expected there would be less immunity following two years without the flu circulating in Australia.”
Of growing concern is a fast-moving outbreak in children, which triggered a 500 per cent increase in flu cases detected in the Royal Children’s Hospital lab in the past two weeks. Some children have also been hospitalised with the flu.
The flu is also tearing through Victorian schools, with school-aged children making up almost half the total reported number of flu cases so far this month.
The outbreak prompted a move by the state government to amend regulations, paving the way for pharmacists to administer flu jabs to Victorian children five years and older for the first time.
Professor Ian Barr, deputy director of the WHO Collaborating Center for Reference and Research on Influenza, said reported cases were likely the tip of the iceberg and that infection numbers could be more than 10 times than those notified on surveillance databases.
“Clearly we are going to have a significant flu season,” Barr said. “Whether it will be a prolonged and severe season or whether it will have a shorter run remains to be seen. But we should be prepared for the worst.”
Asked whether people will get more sick from the flu this year due to being shielded from it for two years, Barr said it was difficult to say.
“Certainly, people’s immune levels will be down because they haven’t seen influenza for a few years and some kids won’t have seen influenza at all, so they may have more severe or longer periods of infection,” Barr said.
“It is a little hard to tease out whether the two [flu] strains that are co-circulating are radically different to previous strains.”
But Barr said it was typically the size of the outbreak, rather than the emergence of a new strain, that determined whether a flu season would be severe.
“The more people infected, the more people who may do poorly,” he said.
During Australia’s last flu season in 2019, more than 950 people died, including a one-year-old child. At least 378 Australians aged between one and 100 died with influenza in 2018.
Mukesh Haikerwal, who runs a medical practice and respiratory clinic in Melbourne’s west, said his staff were detecting between 20 and 30 new influenza cases a day, compared with just a handful a week in March.
Some patients were very ill, he said, but others experienced milder symptoms and recovered within a week.
“The real worry is we are not even close to the peak yet,” he said.
Geelong GP Bernard Shiu estimates his clinic was treating about 30 new influenza patients a day. Cases were far surpassing coronavirus infections in children, he said.
“There’s been a very sharp rise in flu cases the last three weeks,” Shiu said.
The GPs joined a growing chorus of health experts urging all Victorians to get vaccinated against the flu, with immunization rates down compared with pre-pandemic years.
They said those who were susceptible to adverse outcomes from the flu – including people aged over 65, pregnant women and children under five – should get vaccinated as soon as possible.
Only about 15 per cent of Australians have had this year’s flu vaccine, compared with 49 per cent of the population at the same time last year.
This week, the Australian Medical Association called for voluntary mask-wearing in settings with a high chance of spreading influenza and coronavirus, amid crippling demand on the state’s hospitals and ambulance services.