Top doctor wants more MMR tests to satisfy parents

The senior author of the study that triggered fears of a link between the MMR vaccine and autism will break his silence today by calling for urgent research to "resolve the genuine concerns of parents".

In a letter published in The Lancet, Professor John Walker-Smith says large population studies make it clear that "the MMR vaccine is safe in most children". But these studies do not rule out the possibility that, in a "very small group" of children, there could be a link between the jab and bowel and behavioural disorders.

To resolve the controversy, and to end the "heartache" suffered by parents, biological studies must be carried out to determine what causes the bowel and behavioural problems, he says.

Professor Walker-Smith, of the Wellcome Trust Centre for the History of Medicine, in London, says he "continues to support the MMR vaccine" and reveals that three of his grandsons have received the jab. Nevertheless, his letter could serve to deepen the dispute.

Before retiring from London's Royal Free Hospital in 2000, he supervised the work of Dr Andrew Wakefield and was the senior clinical investigator behind the 1998 study in The Lancet that provoked the scare.

The research team, led by Professor Walker-Smith and Dr Wakefield, identified a "highly selected group" of 12 children with an unusual bowel disorder and developmental problems but it was unable to prove a link with the MMR vaccine.

In today's letter, Professor Walker-Smith says that the latest studies have provided evidence that the measles virus, rather than the MMR vaccine, may have a part to play in developmental problems. He writes: "There is now a case to be answered. This study finding needs urgent attention and elaboration of its importance."

Professor Walker-Smith has remained silent about the MMR controversy since 1998. But in his letter today, he says he is speaking out because the debate has gone on for "far too long and is causing so much heartache in parents".

Referring to the large number of studies that have found no evidence of a link between MMR and autism, he says: "It seems clear to me that what epidemiology has shown is that the MMR vaccine is safe in most children."

But, having seen the "grave concern" of parents who have autistic children, he says, "further urgent research is needed to resolve the genuine concerns of parents who associate MMR with the onset of autism and to try to identify whether there are factors that may place a very small but important group of children at risk of such a disorder".

An editorial in the same journal says all the epidemiological evidence shows MMR is safe but swift action is needed to restore public confidence if deaths from measles, mumps and rubella are to be prevented.