The life of 23-year-old Nathaniel has been hanging in the balance this week.
It started with a temperature and then shivers.
His mother, Lisa, said his face then turned grey and his chest X-rays showed white fluid – but the lungs should show black, meaning they are filled with air.
He is now in Royal Prince Alfred Hospital and connected to a heart lung machine.
Nathaniel’s battle for life shows it is not only the vulnerable at risk, with young and otherwise healthy patients also severely affected.
And there is a health alert for Sydney following a surge in the number of patients being admitted to intensive care with the flu.
One man has died and several others have been placed on heart and lung machines.
Mum Lisa said: “I just can't believe how dangerous the flu has become. [He] couldn't breathe anymore and it was just so quick and deadly.”
One doctor treating Nathaniel said: “It is taking blood out of his body out of his body, putting it through an oxynator and returning blood to the heart so completely taking over function of the lung."
In recent weeks the Royal Prince Alfred Hospital alone has had ten flu patients on life support.
Specialist Dr Paul Forrest said: “We've had a man in his fifties pass away a few weeks ago. He wasn't at high risk of getting a severe flu but nevertheless it was a fatal outcome."
It has been the busiest flu season since the swine flu pandemic five years ago.
Last year there were over 8000 cases of flu reported across NSW. This year that has jumped to more than 14,500.
Flu patients who end up in hospital spend on average ten days being kept alive by technology. Remarkably, in most cases after recovery, there is little sign they've been sick at all."
Nathaniel's family lost their home in last year;s Coonabarabran bushfires. Now they are warning others about the flu while doctors urge flu shots.
Lisa added: “We could potentially lose our son from this. He's not out of the woods yet."