The medical journal which originally published the discredited research linking autism and MMR has now issued a full retraction of the paper.
The Lancet said it now accepted claims made by the researchers were "false".
It comes after Dr Andrew Wakefield, the lead researcher in the 1998 paper, was ruled last week to have broken research rules by the General Medical Council.
The publication caused vaccination rates to plummet, resulting in a rise in measles.
The Lancet had already issued a partial retraction.
In 2004, editors argued they had been right to publish it as the journal was there to "raise new ideas".
But they accepted that in hindsight they may not have been, after accusations of a conflict of interest - Dr Wakefield was in the pay of solicitors who were acting for parents who believed their children had been harmed by MMR.
But this move goes further by accepting the research was fundamentally flawed because of a lack of ethical approval and the way the children's illnesses were presented.
The statement added: "We fully retract this paper from the published record."
Last week, the GMC ruled that Dr Wakefield had shown a "callous disregard" for children and acted "dishonestly" while he carried out his research. It will decide later whether to strike him off the medical register.
The regulator only looked at how he acted during the research, not whether the findings were right or wrong - although they have been widely discredited by medical experts across the world in the years since publication.
After the hearing, Dr Wakefield, who now lives and works in the US, said the findings were "unjust and unfounded".
Professor Adam Finn, a leading paediatrician based at the University of Bristol Medical School, said: "This is not before time. Let's hope this will do something to re-establish the good reputation of this excellent vaccine.
"And I hope the country can now draw a line under this particular health scare and move onto new opportunities for vaccination."
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