A virulent flu strain this winter is expected to make more Australians susceptible to deadly pneumonia, a leading diseases expert says.
The warning comes amid a survey showing seven out of 10 elderly and ill Australians can't tell the difference between the flu and the infectious lung ailment, which can spread through sneezing and coughing.
Infectious diseases expert Professor Robert Booy, from the National Centre for Immunisation Research and Surveillance, says the H3N2 flu strain is set to hit Australia this winter, following deaths in the northern hemisphere in early 2013.
"In the northern hemisphere, compared to the year before, we saw a lot more hospitalisations and deaths in high-risk people, including the elderly," he told AAP.
"It's worse than it was the year before, and the year before that, so it's the worse for the last few years.
"I don't have a crystal ball but we're concerned generally in Australia that we will experience this winter what the northern hemisphere did."
People over 65, smokers, diabetics and those with weak immune systems are, in turn, more likely to catch pneumonia as the flu weakens the lining of their lungs, increasing the risk of bacterial infection.
"The influenza sets things up, then pneumonia kills you."
Older and chronically-ill Australians are being urged to get immunised against pneumococcal pneumonia, with Prof Booy expecting the flu risk to heighten from June to August across the southern hemisphere.
The pneumonia warning comes after 70 per cent of at-risk adults admitted they couldn't tell the difference between influenza and pneumonia.
The illness can be spread through bacteria, fungi or a virus, and includes symptoms such as breathing difficulties, coughing, fever, chills and loss of appetite.
The Lung Foundation of Australia's survey of 600 people coincides with Pneumonia Awareness Week.