Oliver's mother believes the vaccine triggered health problems
Five-year-old Oliver Loch, from Marshfield near Cardiff, was treated at the Royal Free Hospital in London, where controversial research into the effects of the MMR triple vaccine took place.
Dr Andrew Wakefield, whose research led him to suggest there was a link to autistic-like disorders and bowel problems in children, has resigned after being told his work was not in line with the hospital's policy.
Oliver's parents Peter and Julie Loch said on Sunday that they were outraged at the way Dr Wakefield's research was received, and insisted he must be allowed to continue.
Oliver is now a happy, contented child who tries to lead as normal a life as possible, despite being diagnosed as autistic.
But ever since he was a toddler, he has suffered a severe bowel disorder which has hampered his development and which means he will need specialised care for the rest of his life.
His mother Julie believes his problems were triggered by the MMR vaccine, which Oliver was given in September 1997, when he was 14 months old.
It was not until Oliver was treated at the Royal Free Hospital in London more than a year later that treatment was begun to help alleviate his symptoms.
"Before my son was seen at the Royal Free Hospital, he was in constant pain," said Mrs Loch.
"He could only express this by means of tantrums and by exhibiting self-injurious behaviour.
"When my son was at his lowest ebb, and we were in a state of complete despair, Dr Andrew Wakefield and his colleagues were the only professionals in the United Kingdom who were prepared to listen and to help," said Mrs Loch.
A wide-ranging analysis of research into the measles, mumps and rubella vaccine has suggested parents should not be worried about giving their child the jab.
Researchers from St George's Hospital, London, and the Institute for Child Health said the worries about potential side-effects of the vaccine were unfounded.
But they said there was no research to support the safety and effectiveness of giving the vaccines singly - as critics of MMR suggest.
Researchers also criticised a recent paper by Dr Wakefield and a colleague which claimed safety trials of MMR had not been carried out for long enough to pick up long-term side effects.
Government reassurances of the safety of the MMR vaccine have not quelled the concerns of some parents and doctors.
Despite a £3m publicity campaign aimed at reassuring parents about the vaccine's safety, 2,000 families in Britain have taken legal action claiming their children have been damaged.