“I knew that Methylmercury in the Lipid Nanoparticles of the mRNA bioweapons would be bad,” the post reads.

“An emerging ‘Kawasaki-like’ disease associated with COVID-19 appears to be a distinct syndrome.

“This means Kawasaki is associated with any injections received of the Lipid Nanoparticle mRNA shots, which carries more methylmercury than the exposure to the inhaled Bioweapon labeled (sic) COVID.”

Kawasaki disease is a rare illness that mainly affects children under five, resulting in inflammation in blood vessels presenting as rashes and fevers.

AAP FactCheck has previously debunked claims about COVID vaccine ingredients being secret.

Companies are legally required to publish all the ingredients in medications and vaccines on the Therapeutic Goods Administration (TGA) website.

Jane Frawley, a senior lecturer in public health at the University of Technology Sydney, told AAP FactCheck in 2022 the TGA has a rigorous process of assessing new vaccines that includes a thorough and independent review of each submission.

“The TGA decided that the Pfizer COVID-19 vaccine (including all its ingredients) met the high safety, efficacy and quality standards required for use in Australia,” Dr Frawley said.

Paul Griffin, director of infectious diseases at Mater Health Services, said there is no methylmercury in the full list of ingredients for either the Pfizer or the Moderna mRNA vaccines.

“There have been many posts claiming these vaccines contain a number of unusual or hidden ingredients, however these are not true,” he said.

Professor Griffin told AAP FactCheck claims of thimerosal or ethylmercury, compounds that contain mercury, in COVID vaccines are also false.

“Thimerosal or ethylmercury has been used to prevent the growth of bacterial germs in multi-dose vials of flu vaccine,” he said.

“While not in the COVID-19 vaccines, even in the vaccines in which it has been used it has been shown to be safe at the minuscule concentrations used.”

The cause of Kawasaki disease is unknown but it is most likely triggered by an infection and cases have been increasing progressively, highlighted by a study covering the 25 years to 2017.

Prof Griffin said cases of Kawasaki disease did increase during the pandemic in many places such as the UK, France and Italy.

However, a US study also shows pandemic measures such as masks and school closures lowered the incidence of Kawasaki disease by 28 per cent, suggesting the cause of the disease likely has a respiratory portal of entry.

Prof Griffin says there is less evidence to suggest the rare disease is caused by COVID vaccines.

“While Kawasaki disease has been reported in many sources following COVID-19 infection, there are also a very small number of reports of possible Kawasaki disease following COVID-19 vaccination,” he said.

However, he added that even if there was the possibility of an association, “it would be far less so than from the virus itself”.