At the height of the controversy over the possible implications of Dr Andrew Wakefield’s initial findings, the UK Department of Health produced ‘The Danish Study’ as proof of no link between MMR and autism. At the time, the study was criticised as irrelevant to the UK experience because Danish children, unlike UK children, had not had their immune systems damaged by exposure to thimerosal (the mercury-based preservative used until very recently in several vaccines in the UK).

Dr. Dick van Steenis also wonders whether the Danes' decision to limit their research to children four years and younger was appropriate. When the study was later extended to include children five years old they found that autism levels had increased eightfold since 1995.

As usual, things are never that simple. It was also in 1995 that the Danes began to burn bitumen (a tar-like petroleum waste product often used on roofs and roads) in their waste incinerators. Was it this, or MMR, or a combination of the two, which led to the soaring epidemic?