Western Australia's peak medical body has warned parents considering joining a no-vaccination playgroup advertised on social media that the consequences of a disease outbreak could be severe for their kids and the community.
A Facebook post, which was shared to a closed community site, asked parents interested in joining to get in touch.
"We have one location so far, but I'm hoping to have free playgroups going all across Perth every day of the week eventually," the poster, pictured with two children, wrote.
"Please, no nasty comments from those whose beliefs differ from my own. Let's all respect that we each have the right to make decisions for our own families regarding their health and welbeing (sic)."
WA Australian Medical Association president Dr Andrew Miller said unvaccinated children who were taken to the group would be at risk, as would the wider community.
"That's a bit like getting all the dry grass together in one spot and throwing a match in it," he said.
"If there was an exposure to, for example, measles, then it would spread very rapidly through a large group of children.
"These children could well become very sick, and some of them could die as a result."
He said people in the community including infants and those who are sick, such as cancer patients, would be vulnerable to diseases if they came into contact with the children.
The ABC was unable to contact the person behind the anti-vaccination playgroup advertisement.
It comes as the WA Health Department calls on parents to make sure their children are up to date with vaccines, and anti-vaxxers get set to show a controversial movie in Perth claiming current vaccines are not safe.
Western Australia has the lowest vaccination rates for children around the country.
Parents urged to keep kids up to date
The WA Health Department today issued an alert to parents to ensure any children being enrolled in school have their immunisations up to date.
The state's childhood immunisation program currently includes immunisations against 16 vaccine-preventable diseases, including whooping cough, which claimed the life of an infant Riley Hughes in 2015.
In the statement, WA Health medical coordinator Professor Paul Effler urged parents to have their children fully immunised to protect them, and to stop the spread of preventable diseases.
"Infectious diseases can spread quickly in a school environment," he said.
"For children to stay healthy and reduce the spread of disease it is important to ensure they have completed the full immunisation schedule."
He said while immunisation rates were rising in WA and were at 91.5 per cent this year, it needed to be 95 per cent for "optimal community protection".
In early May, figures showed rates of dangerous vaccine-preventable disease like whooping cough was down on the same period in previous years.
However, there have been 12 cases of measles, up from zero last year and just two in 2015.
There have also been two cases of rubella, whereas there were none on the same period in the previous two years.
Chicken pox and shingles cases are also up, but influenza cases are down.