Strapping young Brayden Chater was a great defender for his local rugby league team who loved to tackle.

Which is ironic, because the lack of a meningococcal B vaccine on the NSW immunisation schedule left him completely defenceless against the disease which would kill the handsome 23-year-old plumber from Wollongong.

He didn't even have a chance to tackle the sickness which took hold of him rapidly, leaving him brain dead only hours after a day of paintballing with his work colleagues.

His mum, Stacey-Anne Chater, describes Brayden as a "typical Aussie young bloke"; a bit of a "mama's boy", a joker and keen fisherman who enjoyed a punt and was a loving and protective brother and friend.

He was popular - up to 200 people came through the hospital to say goodbye to him before his life support was switched off and some 600 attended his funeral, she says.

"I think there's about 20 people with some kind of tattoo dedicated to him," she told AAP.

And while Ms Chater says Brayden was "a ladies man", he was the type to stay friends with all the girls he dated - so much so that a group of his ex-girlfriends will all be together attending a special celebration day at the Kembla Grange races to mark what would have been his 24th birthday.

Ms Chater walked in on her son "thrashing about" in a fit and unresponsive on his bedroom floor one evening in November 2022.

Hours later, she was told he was brain dead.

The shock of losing her son was devastating, but discovering that the disease that cut Brayden down in the prime of his youth could have been avoided if meningococcal B was included on the NSW immunisation schedule - like the other most common strains A, C, W, and Y - was heartbreaking, she says.

She has joined forces with Meningitis Centre Australia to petition for its inclusion, and spent the past week at parliament urgently trying to convince MPs to get behind her cause.

"I'd love it (to be available) Australia-wide," she said.

"So no one else has to go through what our whole family and community is going through right now."

The meningococcal B strain is the most common cause of illness, disability and death of all strains in Australia but is only available under the National Immunisation Plan to Indigenous and immune-compromised children.

Already in 2023 there have been more than 70 cases, including 21 in NSW, with the numbers expected to exceed those of the previous year.

It has prompted Queensland and South Australia to include the strain on their state plan but families in NSW must cough up about $400 for the required two doses and GP fees.

There is a strong financial argument for pursuing its inclusion with the average cost per meningococcal survivor totalling more than $10 million in their lifetime, Meningitis Centre Australia's CEO Karen Quick said.

"If a baby or adolescent is lucky enough to survive meningococcal B, it's likely they will develop permanent and sometimes devastating complications, and this affects the whole community," she said.

"Queensland recently did the maths and worked out they would save more money than the cost of the vaccination itself - it's a preventative measure that will save the taxpayer money in the long term.

"There is no reason NSW can't do the same right now."

Ms Chater is pleading with the state government to make the change so that no other families have to go through a similar unnecessary and heartbreaking tragedy.

"The NSW government needs to protect our children and teenagers, they don't have to wait for the red tape of the federal government," she said.

"I know they can do this now so no more mothers lose their children like me."

NSW Health said it would continue to closely monitor the spread of meningococcal B and respond based on the best available evidence.