To call a national press conference in order to announce the results of a scientific trial is rare. For a prestigious teaching hospital to do so for a study involving just 12 children is unprecedented.

So when journalists were called to attend an urgent press briefing at the Royal Free hospital in London in February 1998 they arrived expecting a scoop.

Under television lights, five doctors, including the dean of the medical school, lined up to make their announcement.

They had, they informed the hushed room, important news from the front line of medicine: injections of the combined measles, mumps and rubella vaccine (MMR) had been linked for the first time to a bowel disorder and the onset of a severe form of regressive behaviour, generally known as autism, in children.

Richard Horton, the dapper young editor of The Lancet, waited expectantly in his office for the reaction.

It was shocking news by any standards. Government policy dictated that every child should receive the first of two MMR inoculations between 13 and 15 months. Thousands of jabs were being given daily. Now parents were being told that the vaccination might be associated with a form of serious brain damage in children.

Advance copies of The Lancet’s sensational study were quickly distributed. “Twelve children were referred to (the hospital) with a history of normal development, followed by a loss of acquired skills, including language, together with diarrhoea and abdominal pain”, read its remarkably media-friendly opening page.

“Onset of behavioural symptoms was associated, by the parents, with measles, mumps and rubella vaccination in eight out of the 12 children.”

Eight out of 12: it was a stunning proportion. Worse, the damage had become evident on average just “6.3 days” after the jabs were given.

Professor Arie Zuckerman, dean of the medical school, then sounded a word of caution. It was “absolutely essential” that public confidence in MMR was not damaged by the publication of the study. Eight children did not, after all, provide proof of a link between MMR and autism, he noted.

However, if Zuckerman was cautious, others were not. At the centre of the speakers’ table sat the principal author of the study, Dr Andrew Wakefield. Cutting a dashing and charismatic figure, the young gastroenterologist had a very different message to impart. Yes, it was just one study and yes, there was no proof, but he personally believed that action was needed.

“One more case of this is too many,” he declared.

“It’s a moral issue for me and I can’t support the continued use of these three vaccines given in combination until this issue has been resolved.” He wanted single jabs.

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