The MELISA test is being used in research to investigate a possible link between childhood vaccines and autism. The theory rests on a hypersensitivity to thimerosal (or ‘thiomersal’), a preservative used in many vaccines for decades, in children who experience side-effects after vaccination. The controversy is at its strongest in the United States, where it has been removed from routine childhood vaccines. Thimerosal is 50 per cent composed of ethyl mercury, a type of organic mercury, which is used as a preservative, mainly in whooping cough vaccines. It is not added to live vaccines, such as MMR. Its use was justified on the grounds that the cumulative amount of mercury administered to the infant is below a certain safety limit.
The debate so far has focused on the toxicological effects of thimerosal, but there has been little consideration about the potential effects of hypersensitivity to thimerosal and whether this could result in neurological damage.
In 2001, the Institute of Medicine stated it is “biologically plausible” that ethyl mercury thimerosal in vaccines caused neurodevelopmental disorders such as autism.

More information:

Thimerosal and autism symptoms resource

US Center for Disease Control (CDC) on thimerosal:

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