A doctor described Adam Smith as "the sickest man in NSW" after a severe illness caused gangrene in his hands and feet, which will require amputation.
Mr Smith was a healthy and fit 50-year-old, but after contracting influenza A his illness progressed to pneumonia and sepsis.
The Central Coast resident was in an induced coma for three weeks.
He has no feeling in his hands and feet and also suffered kidney failure requiring dialysis.
Doctors have confirmed that his hands and feet will require amputation, but tests will determine how much of his limbs need removing.
His mate Mark Elliott has organised a GoFundMe campaign to help with his recovery.
Mr Elliott, who has visited him in hospital, said "his spirit is quite good".
His kidneys have started to recover, raising hopes that he won't need to continue on dialysis.
Before he was in hospital, Mr Smith had flu-like symptoms on and off for a couple of months.
As men often do, he put off seeing a doctor. He didn't go to work on July 19, which was unlike him.
A family member couldn't reach him by phone, so went to his house and found him inside. He was unable to get off the lounge.
An ambulance was called and within the next hour he was on life support.
He was airlifted to Royal Prince Alfred Hospital at Camperdown on July 20, where he was placed in an induced coma.
He worked in juvenile justice and for a not-for-profit organisation in Gosford that supports young people at risk.
"He's always cared about the community and has a strong love for animals. He'd pick them up off the street and look after them," Mr Elliott said.
"Adam has a very special quality to see the best in everyone. He has a saying that 'we can all help our future by helping our youth'."
He enjoyed bushwalking, swimming, going to the gym and photography and did not smoke or drink alcohol.
"He would travel for hours to find perfect spots to photograph," Mr Elliott said.
As a boy, he would bring home lost and wounded animals of all sizes, including snakes, turtles, dogs, cats, lizards and birds.
Mr Smith told family that he intended to "walk out of hospital with prosthetics".
He was given a toy lion for his 50th birthday in hospital to symbolise courage. His goals are to drive his car again and go to the gym.
Mr Elliott believes that raising awareness of Mr Smith's illness is important.
The Newcastle Herald reported last month that Dr Fiona Van Leeuwen, chair of the Hunter General Practitioners Association, said "don't underestimate influenza".
She said people shouldn't dismiss symptoms such as high fevers, body aches and a cough.
"It's important that if people are unwell they seek medical attention promptly," she said.
Pneumonia is a common and potentially fatal lung infection that can be caused by viruses, bacteria or fungi.
NSW Health says the pneumococcal vaccination is "the most effective way to prevent infection" with the bacteria Streptococcus pneumoniae, which is one bug that can cause pneumonia.
NSW Health data shows Hunter New England recorded 80 to 190 influenza and pneumonia-related deaths each year over the past 20 years.
The National Centre for Immunisation Research and Surveillance states that "influenza vaccination is recommended for all people aged over six months, unless contraindicated".
"Influenza is a common cause of hospitalisation and death in Australia," it states.
"Vaccination is the only way to specifically prevent influenza infection and its complications."
Australia's national sepsis program says the disease is a "time-critical medical emergency that arises when the body's response to an infection damages its own tissues and organs".
It can lead to "failure of multiple organs and death, if not recognised and treated promptly".
"Sepsis can occur in response to various types of infections, including bacterial, viral or fungal infections which are acquired both in community or healthcare settings."
