Tony Blair yesterday stepped into the furore surrounding MMR vaccination after the Government's chief medical officer dismissed the controversial research which led to the scare linking it to autism as "poor science".

Mr Blair said: "There's absolutely no evidence to support this link between MMR and autism. 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.''

Sir Liam Donaldson, the chief medical officer, had earlier accused Dr Andrew Wakefield, whose 1998 report prompted the row, of "mixing spin and science". He blamed his paper for a loss of confidence in a vaccine which had saved millions of children's lives.

On Friday, The Lancet's editor Dr Richard Horton revealed he would not have published the research if he had known then that Dr Wakefield was at the time being paid to investigate bringing legal action by parents who thought their children had been damaged by the vaccine.

While Dr Wakefield has robustly stood by his research, John Reid, the Health Secretary, demanded that the GMC investigate. The GMC has confirmed it is considering doing so.

So what are the facts about this ongoing controversy?

The Facts

  • The combined measles, mumps and rubella vaccine was introduced in the UK in 1988.
  • MMR protects against three of the commonest childhood diseases. Measles is mostly a mild disease but in severe cases can cause encephalitis (swelling of the brain) leading to permanent brain damage. The death rate is one in 10,000 cases. Mumps causes swelling of the glands and can damage the testicles in boys leading to sterility. Rubella (German measles) is dangerous if caught by pregnant women when it can cause blindness and other deformities in the unborn child.
  • More than 500 million doses of MMR have been used around the world since the early 1970s. The World Health Organisation says MMR has an outstanding safety record. Before MMR was introduced, there were regular epidemics of measles.
  • MMR vaccination is given at 13-15 months. After the first dose 5-10 per cent of children remain unprotected against the disease, so a second dose is given at age four to five, before the child starts school. After two doses, less than 1 per cent are left unprotected.
  • MMR is used in 90 countries. No country recommends giving MMR as three single vaccines.

The Claims

  • In 1998, Andrew Wakefield, a researcher at the Royal Free Hospital, London, published with colleagues a paper in The Lancet identifying a new inflammatory bowel disease linked with autism and suggested it might be associated with MMR vaccination.
  • At a press conference to launch the paper held at the Royal Free Hospital in February 1998, Dr Wakefield recommended that parents should ask for the MMR vaccine to be split into three single vaccines and given a year apart to reduce the impact on the child's developing immune system.
  • His critics said there was no evidence that giving vaccines together had a damaging effect. They pointed out that children were exposed to infection with multiple viruses simultaneously in their normal lives without long-term harm.
  • Parents whose children have developed autism say the problems first appeared after they had MMR vaccine. Doctors say the first signs of autism appear in the second year of life, and the link with MMR is co-incidental.

The Realities

  • The Wakefield paper sparked a scare about MMR which is still reverberating six years later. National vaccination rates fell from over 90 per cent to below 80 per cent and have dropped below 60 per cent in some areas.
  • As parents have turned away from MMR, demand for single vaccines has risen. The Government has refused to provide single vaccines on the grounds that the combined MMR vaccine is safer because it is given in two doses instead of six and there is less chance of children catching the diseases while waiting for full immunisation cover.
  • Parents have protested that they have been denied the choice over a fundamental decision about how to protect their children. Many have paid hundreds of pounds to have single vaccines for their children administered at private clinics.
  • Numerous studies have examined the link between MMR vaccine and autism suggested in Wakefield's 1998 paper but none has confirmed it.
  • Wakelfield and his colleagues continue to publish papers which have kept the controversy alive. They say subsequent studies have identified measles virus in 91 children with bowel disease and autism.

The Questions

  • Is Andrew Wakefield being attacked because of his findings or because of a potental conflict of interest?
  • Is there evidence of an orchestrated Government campaign against him?
  • Why have other research papers been accepted for publication in The Lancet when a potential conflict of interest exists without there being such controversy?
  • Why, given his tough comments yesterday, has Mr Blair never said whether his son, Leo, has had the MMR, when that might have offered much-needed reassurance to parents and so boost the take-up rates?
  • Why has the Government never ordered a clinical examination of children who developed bowel disease and autism following MMR vaccination?
  • Its supporters agree it is impossible to prove that the MMR is safe. What more, then, can be done to reassure worried parents?