The New South Wales Health Care Complaints Commission has taken the unusual step of issuing a safety warning against a group of anti-vaccination campaigners.

The Commission says the group, known as the Australian Vaccination Network (AVN), has refused to include a prominent disclaimer on its website stating the information should not be taken as medical advice.

Australia faced a whooping cough epidemic last year. More than 19,000 cases were reported and three babies died, including four-week-old Dana McCaffery from the NSW north coast.

Paediatrician Chris Ingall treated the sick babies and says immunisation rates have fallen dramatically since the AVN became active in the region.

"They spook many young families into believing that vaccinations are bad, that the risk outweighs the benefit, which is quite wrong," Dr Ingall said.

"Ever since the AVN became active up here, the immunisation rates have fallen. We're the lowest in the state, we have pockets below 50 per cent vaccination.

"Those are the pockets where the pertussis [whooping cough] outbreaks succeeded. Unfortunately it rolls out to the entire community, so everyone gets affected.

"We've seen that in waves over the last two or three years and poor little Dana McCaffery was caught up in one of those waves."

In a statement, the Health Care Complaints Commission said it recognised that it was "important for there to be debate on the issue of vaccination".

"However, the AVN provides information that is inaccurate and misleading," it added.

"The AVN's failure to include a notice on its website of the nature recommended by the Commission may result in members of the public making improperly informed decisions about whether or not to vaccinate, and therefore poses a risk to public health and safety."

AVN spokeswoman Meryl Dorey says people must make informed decisions on all medical issues, including vaccination.

"We already have two of the three items that the Health Care Complaints Commission asked us to put up on the website and we've had these things up there for years," she said.

"The only thing that the AVN refuses to put up on the website [is] the Health Care Complaints Commission wants us to state that we are anti-vaccination.

"We are not, never have been, anti-vaccination. We are pro-information, pro-choice and a health safety watchdog.

"We do refuse to put [the anti-vaccination statement] up and surely this is censorship at its highest level to insist that we [do so]."

Ms Dorey says that since the AVN is neither a healthcare practitioner or educator, it is a breach of the Health Care Commission's jurisdiction to investigate the group.

She says the network is now seeking legal advice.