A huge drop in the number of children having the MMR vaccination has left the UK on the verge of a major measles outbreak, a leading specialist has warned.
The MMR is protection against serious child illnesses
Dr Simon Murch was involved in the original research that led to fears among some parents that the combined measles, mumps and rubella jab was linked to autism.
He has consistently said there is no proven link between the jab and autism and now, writing in the Lancet, he has warned that MMR uptake as low as 60% in some areas is leaving British children vulnerable to disease.
Another of the original authors of the research, Dr Andrew Wakefield, has suggested there is fresh unpublished evidence of a link.
However, the Department of Health has strongly rebutted his claim - made to the BBC - that this was presented to government officials.
They say that no new research has emerged to support fears over MMR.
Dr Murch's warning comes after Scottish health officials said the incidence of suspected or confirmed mumps cases rose by 27%, rubella by 22% and measles by 18% in children under 15 over the past 18 months.
Dr Murch, of the centre for paediatric gastroenterology at the Royal Free Hospital in London, was one of the authors of a 1998 paper published in the Lancet which looked the connection between inflammatory bowel disease and autistic disorders.
The paper found a connection between bowel problems and autism but did not conclude that MMR was connected to this.
However Dr Wakefield, the lead author of the paper, sparked a storm when he went on to raise fears of a link between the combined jab and autism, and recommended the use of single measles, mumps and rubella vaccines instead.
While Dr Murch's name was on the original Lancet paper, he has always advocated continuing with MMR jabs.
Writing in this week's Lancet, Dr Murch states that there is unequivocal evidence supporting the safety of the MMR vaccine.
"No other vaccine has ever been studied in such depth, and the evidence for its overall safety is comprehensive.
He adds: "That any reports that characteristic gut inflammation in autistic children are reported in the media as supporting the idea that MMR is causative is deeply frustrating, since it is simply not so."
Dr Murch adds: "MMR immunisation, which should be an easy decision, has become a worrying issue for many British parents.
"Although this situation reflects in part a broader mistrust of official pronouncements, and has been fuelled by media campaigning, it is founded on the misinformed perception that there is ongoing scientific uncertainty.
"There is now unequivocal evidence that MMR is not a risk factor for autism - this statement is not spin or medical conspiracy, but reflects an unprecedented volume of medical study on a worldwide basis.
"An unprotected child is not only at personal danger, but represents a potential hazard to others, including unborn children. Unless vaccine uptake improves rapidly, major measles epidemics are likely in the UK this winter."
He told the BBC: "You take acceptable risks all the time. I think that anybody who tries to say there is no risk attached to any medical intervention is actually being disingenuous.
"What I'm saying is that the level of risk is clearly extremely small. And the risk attached to not giving MMR is much, much greater."
Dr Wakefield, however, told the BBC that a number of scientists were "increasingly worried" about the possibility of a link between MMR and some cases of autism.
He said: "I can tell you that senior members of the joint committee on vaccination and immunisation in their capacities as expert advisers to the vaccine manufacturers, have been presented with compelling evidence of a link between MMR, bowel disease in children with autism.."
He said he was not in a position to disclose any more information about this evidence.