Immediately after receiving the vaccination, he started to run a high temperature and three weeks later, "went vacant" and started to lose his speech. At the age of two and a half, he was diagnosed with autism.
Daniel is now seven and his parents, Olivia Cooper, 38, and William Docherty, 48, have decided not to give the MMR jag, or single vaccinations for mumps, measles and rubella, to his two younger brothers.
Ms Cooper, who gave up her job as a home caterer to care for Daniel, believes the latest controversy over Dr Andrew Wakefield, who was an author of a paper published in 1998 linking autism and MMR, is just "another attempt to discredit him and fob parents off".
Professor Liam Donaldson, England’s chief medical officer, accused Dr Wakefield yesterday of mixing "spin and science". His words came after the General Medical Council (GMC) said it was carrying out an investigation over claims that the doctor’s research was "fatally flawed" because of a conflict of interest.
Dr Richard Horton, the editor of the Lancet, which published the 1998 paper, has said the research would not have been published had he known then that Dr Wakefield was being paid for a study looking for evidence to support legal action by parents who thought their children had been damaged by the vaccine.
However, Ms Cooper, of Ayrshire, defended the research. She said: "This poor guy is doing nothing but trying to get justice for people who have been a victim.
"The big thing in all this is saying that Wakefield had a conflict of interest, but these are the key words. If you are talking about conflict of interest, there are so many scientific and medical researchers who have a financial interest in companies manufacturing such products. All Wakefield’s interest was being 100 per cent behind the children and the parents who are the victims in all this.
"We are convinced that Daniel’s autism is as a result of the jag and we have decided not to give the jag, or single vaccinations, to his brothers, Campbell, who will be two next month, and Mitchell, who is six months old," she added. "It was not an easy decision as you fear the worst, but you are damned if you do and damned if you don’t."
Prof Donaldson said Dr Wakefield’s research was "poor science" which had led to a loss of confidence in a vaccine which had saved millions of children’s lives. He added that the Lancet’s latest intervention had revealed a "darker side" to the issue and called on Dr Wakefield to respond to a letter sent to him two years ago by Prof Donaldson asking a series of detailed questions about his research.
He said: "When Dr Wakefield has been in contact with us, he has often been represented by a PR company rather than communicating directly. I don’t think that spin and science mix. Now a darker side to this work has shown through, with the ethical conduct of the research, and this is something that has to be looked at."
Dr Wakefield has welcomed the GMC investigation after the "serious allegations" that had been made against him.
A spokesman for the GMC said yesterday: "We have spoken to Dr Wakefield, who has made plain his wish to co-operate fully with any investigation. We will be studying the statement made by Dr Richard Horton, the Lancet chief editor, to determine what action we may need to take. We are unable to comment further at this early stage."
Tony Blair, the Prime Minister, insisted yesterday that there was no evidence to support a link between MMR and autism. He added: "If there was, I can assure you that any government would be looking at it and trying to act on it.
"I hope now that people see that the situation is somewhat different to what they were led to believe, they will have the triple jab because it is important to do it."
During the quarter between April and June last year, the uptake for the MMR vaccine sank to its lowest level in Scotland since the mid-1990s. The number of two-year-olds receiving the jab dropped to 85.9 per cent although experts say an uptake of 95 per cent is needed for a "herd immunity" level deemed to give protection to the community as a whole.
Jackie Fletcher, the founder of the vaccine pressure group JABS, rejected suggestions that Dr Wakefield’s work had been discredited. She said: "Dr Wakefield’s original data is not in question at all and the conclusions from it have not changed. The science has moved on and the original work has been replicated at Harvard University in the States, in Japan, in Ireland and other places."
But a spokeswoman for the Scottish Executive said: "MMR has been the subject of extensive consideration by a wide range of organisations, including an expert group set up by the Executive. The expert group acknowledged, like the health and community care committee, that the current scientific evidence does not support the alleged link between MMR and autism."
LAST year’s take-up rates for the MMR vaccine dropped to the lowest level for at least eight years, showing both widespread confusion and concern about the injections among parents.
The fall followed widespread fears among parents after a paper published in 1998 by doctors, including Dr Andrew Wakefield, at the Royal Free Hospital, in North London, suggested a link between the childhood vaccine, autism and inflammatory bowel disease.
Two months later, a study based on a Finnish vaccination programme, which saw three million MMR vaccines given to children between 1982 and 1996, contradicted the claims.
But the panic among many parents had set in, with headlines such as "Ban three-in-one jab urge doctors".
Fears over the three-in-one jab were also compounded with a rise in the number of children suffering from autism, although critics of this argument claim that the real reason for the increase is a greater awareness of the condition.
A report published in 2002 by an expert group set up by the Scottish Executive concluded that the controversial MMR vaccine was the safest way to immunise children and that children should not be offered single jabs as an alternative.Last summer, at the start of its annual conference, the British Medical Association (BMA) rejected the idea of compulsory immunisation for children but stressed that the triple vaccine was the most effective way to immunise children against measles, mumps and rubella.
The argument for the combined vaccine is that it provides the best-possible protection against the three diseases because single vaccines leave children unprotected for extended periods.
Dr Bill O’Neill, the secretary of the BMA in Scotland, said: "In-depth scientific research to date has repeatedly demonstrated the safety of the MMR triple vaccine and there has yet been no conclusive research establishing a link between autism and the vaccine. Yet despite this, the fluctuations in uptake rates since 1998 clearly reflect public confusion over the safety of MMR."
The National Autistic Society (NAS) has expressed concern at the continuing lack of confidence in the UK vaccination programme arising from public fears of an association between childhood vaccines and autism, and the charity has called for further research to "put the matter beyond doubt".
A spokeswoman said: "The NAS is not a medical charity. It is unable, therefore, to state whether or not there is any link between any vaccine and autism."