The New South Wales Health Care Complaints Commission (HCCC) has compiled a damning report into Australia's most prominent anti-vaccination group, the Australian Vaccination Network (AVN).

The HCCC accuses the AVN of providing inaccurate and misleading information and selectively quoting research out of context to argue against vaccination.

The report has also noted accusations that the AVN harassed the parents of a child who died of whooping cough last year, after the parents advocated the importance of childhood vaccination.

Meryl Dorey runs the AVN from a home office on the north coast of NSW.

The AVN provides anti-vaccination information through its website, magazine and seminars.

An investigation by the HCCC into the AVN has found the information it provides to parents is inaccurate and misleading.

But Ms Dorey told ABC1's Lateline the investigation was biased.

"This was not an independent investigation - this was an investigation by an organisation that set out to support government policy, which is pro-vaccination," she said.

"We do not agree that the HCCC has any jurisdiction over us and we have been telling them this from the very beginning, and we are seeking legal advice on this issue."

Ken McLeod is the man who took the initial complaint against the AVN to the HCCC.

He says the AVN's anti-vaccination stance is indefensible.

"I remember as a six-year-old seeing the look of horror on my father's face as the doctor told him my sister had polio, and my mother just being so shattered," he said.

"I remember going to the hospital ward in Townsville and it was an entire ward full of dozens of kids, little babies with polio, and it was awful - absolutely awful.

"Only a year or so later the polio vaccine came and this just disappeared. It was like magic and it was just wonderful, and all these years later you now find people who are trying to set the clock back 50 years."

Mr McLeod says the AVN are "a bunch of ratbags".

"I mean reason and science just does not break through [to them]," he said.

"They're not interested in reality, they're interested in conspiracy theories and junk science."

More and more people rely on the internet for health care information.

If you Google "vaccination", the AVN comes up second on the list of sites. But nowhere on its website does the AVN declare it is an anti-vaccination organisation.

But Ms Dorey says the AVN has never claimed to "provide both sides of the story".

"Our position is to provide information that balances the information that parents get from their doctors and from the Government," she said.

Harassment claims

Dana McCaffery died of whooping cough in March last year.

She was 32 days old - too young to be vaccinated against the disease also known as pertussis.

What her parents Toni and Dave did not realise was that they lived in an area with one of the lowest rates of childhood vaccination in the nation, and one of the highest rates of whooping cough.

The McCaffery's live just a few kilometres from the headquarters of the AVN.

They say they have been harassed by the AVN since their daughter died and that the AVN has made repeated claims that Dana did not die of pertussis.

"Our daughter wasn't even buried and it began," Ms McCaffery said.

"It began the day before her funeral, it began with phone calls to the health department to get her medical records, contending she didn't die of pertussis."

An email from Paul Corben, the director of Public Health at the North Coast Area Health Service, backs up Ms McCaffery's claims.

In the email, Mr Corben says Ms Dorey called him on March 12 seeking details of Dana's death and accusing him of misleading the public by attributing the cause to pertussis.

Ms Dorey denies the claims. She repeatedly says Dana "supposedly" died of pertussis, but the McCaffery's say that is an offensive claim.

"It's the most offensive statement because I watched over five days my beautiful daughter suffer the most agonising death," Ms McCaffery said.

"Then to be put in a position where I have to prove that she died of pertussis, that's even crueller."

Mr McCaffery says Ms Dorey is "diminishing the fact that pertussis can and does kill".

"It is going to lead to someone making a decision that could put their baby or their family at risk, and that's not right," he said.

The McCaffery's have made their own complaint to the HCCC about the AVN.

They have continued to advocate publicly for vaccination and say the AVN continues to publish false and hurtful comments about them.

They say an AVN representative posted a message on Facebook urging them to "tell the whole story".

"One day I hope the parents of this baby tell the whole story and are able to see how they have been used by a group of ruthless scumbags with alterior (sic) motives," the Facebook post said.

"Then maybe they will be able to honour their child's life with the truth."

Mr McCaffery says the comment is "reprehensible".

"To suggest that we're being used by a group of people - that we're not honouring our daughter's life with the truth - is just reprehensible. They are terrible people," he said.

The HCCC report is expected to be made public within the next two weeks.

The AVN has been given 14 days to comply with the HCCC's findings and place a statement on their website telling consumers they provide anti-vaccination information and that the information should not be read as medical advice.