Mark Watts reports on the potentially dangerous side-effects of the MMR vaccine

Katie Stephen was a healthy baby girl when she was injected with the MMR triple vaccine. Ten days later she was vomiting, delirious and running a fever.

	The Urabe MMR vaccine has been linked to cases of encephalitis

That was in 1990. Seventeen years later, she is deaf in one ear.

Following the debate over MMR and its alleged link with autism, government documents just released under the Freedom of Information Act show there was another, earlier concern for which there was more evidence and, apparently, more immediate risk. Whitehall experts knew of it before MMR's mass introduction into Britain, but the public was kept in ignorance.

Katie's symptoms were consistent with those of encephalitis, which can cause brain damage or even death. Her mother Wendy, a former psychiatric nurse, is convinced that the first variant of MMR used in Britain is responsible.

Mass immunisation with the combined measles, mumps and rubella vaccine began in Britain in October 1988. Ten years later, Andrew Wakefield, a researcher at the Royal Free Hospital in London, suggested the vaccine might increase the risk of autism and bowel disorders. But at least eight months before the first British children were injected with MMR, the government working party set up to introduce it was already aware of another potentially dangerous side-effect.

The newly released documents include the minutes of a meeting of 15 experts and officials held in February 1988. According to the minutes, the group "read a report of cases of mumps encephalitis which had been associated with MMR vaccine containing the Urabe strain of the mumps virus. The Canadian authorities had suspended the licences of MMR vaccines containing the Urabe strain."

This was bad news for the government: the Urabe strain was to be used in 85 per cent of early MMR injections. Canada did not withdraw the licences for Urabe MMR, but stopped using it as a precaution.

In early 1987, just after the Thatcher government decided on MMR as an option in mass vaccinations, doctors in America had already reported "adverse reactions" to Urabe MMR. A few months later, the Swedes reported 52 cases of "febrile convulsions probably associated with MMR vaccination".

Then, in Britain, five cases of convulsions were reported in children taking part in an MMR trial in Somerset, although only three of these appeared to be related to the triple vaccine. A meeting of the government's Joint Committee on Vaccination and Immunisation (JCVI) noted: "This gave a rate of three convulsions per thousand doses of MMR."

The group "expressed concern" about giving triple vaccines to children with a personal or family history of convulsions. Nevertheless, the British immunisation programme involving Urabe MMR went ahead in 1988.

Toby Stewart of west London was one of the children given it. He soon developed encephalitis-type symptoms and was left with what his father Andy, a business consultant, describes as "low-scale brain damage". Mr Stewart believes his son was the victim of cost-cutting - Urabe MMR being cheaper than MMR2.

Toby was one of the last British children to be injected with Urabe MMR. After the start of mass immunisation, more alarming evidence surfaced around the world. Canada, having stopped using Urabe MMR in 1988, withdrew licences for the vaccine in May 1990. Malaysia, the Philippines and Singapore soon followed.

In the same month, the JCVI's "adverse reactions" sub-committee expressed "special concern" over reports from Japan linking Urabe MMR with high levels of meningoencephalitis.

It took until 1992 for Britain to stop injecting children with Urabe MMR, replacing it with MMR2, which contains a less potent form of the mumps virus. And, according to the minutes, that action owed more to the decision of the manufacturers of Urabe MMR to cease production. Revoking the licence would have cast light on Whitehall's decision to use Urabe MMR on British children despite disturbing evidence of its potential effects.

The minutes of Whitehall committees dealing with the triple vaccination have been obtained by the FOIA Centre, a research company, on behalf of parents involved in a group action for damages against a number of pharmaceutical companies for an array of conditions allegedly caused by MMR.

The discussions uncovered began 20 years ago, but Mrs Stephen still feels betrayed. Mr Stewart is equally bitter. "These documents," he says, "confirm our worst fears."