Flu season warning as international borders reopen

Australians should brace for a big jump in influenza cases over the coming months as international borders reopen, health experts warn.

This year there have been just 598 laboratory-confirmed influenza cases in Australia, Federal Department of Health figures show.

This was in stark contrast with the last pre-coronavirus pandemic flu season of 2019 which had more than 300,000 infections.

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But small numbers of influenza cases have already been detected in Australia from overseas visitors. Dr Sheena Sullivan, from the WHO Collaborating Centre for Reference and Research on Influenza, confirmed the cases among international travellers in a Medical Journal of Australia article.

Infections had been reported in people from south Asia who had arrived at the Howard Springs quarantine facility in the Northern Territory.

"As the influenza incubation period, infectious period, and serial interval are short, the current duration of hotel quarantine (14 days) has prevented people leaving quarantine while still infectious, even in the context of chains of transmission within travelling groups," Dr Sullivan wrote.

"However, if quarantine periods are reduced or eliminated, infected travellers may enter the community and instigate local outbreaks."

Dr Sullivan recommended that all returning travellers be vaccinated against influenza prior to them boarding the plane.

"Given the similarities in disease presentation, diagnosis, and management, the wealth of resources made available during the COVID-19 pandemic should also be leveraged to mitigate the consequences of influenza outbreaks," she wrote.

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Professor Ian Barr, deputy director of the WHO collaborating centre for reference and research on influenza, said he expected large case numbers next year.

"We're sitting ducks, to be frank, but it's a matter of when that will eventuate," he told The Sydney Morning Herald.

Professor Barr said he was also concerned about the expected rise in quarantine overseas arrivals in the last weeks of this year.

"Now that we've had two years, not one, of low incident seasons, it does raise the fear that we could get a real surge," he said.