Assurances from the UK Department of Health of the safety of the measles jab being given to all British school children is based on flimsy scientific data and assumptions, American counterparts have admitted.

The real safety of revaccinations or booster jabs will not be known for another year when a trial involving 600 children in the US is completed.

Although this was explained by the American National Immunization Program last February to Dr David Salisbury, principal medical officer at the Department of Health (DoH), the British government pressed ahead with one of the most ambitious immunization campaigns ever seen in an industrialized country. They have assured parents that side effects to booster jabs are very unlikely after being "carefully studied by looking at large numbers of children in the United States. . .", as the leaflet given to every schoolchild explained.

However, this was not the information given by the American health authorities. Dr Mark Papania, of the US National Immunization Program, told Dr Salisbury in a letter of 18 February that the safety of the booster jabs is largely based on three studies, two of which were voluntary questionnaires which cannot be regarded as scientific. The third involved just 303 people, not the "large number" suggested by the British government.

The finding of the third, called the Bass study, ". . . supports your (and our) assumption that adverse events are less likely with revaccination", wrote Dr Papania (italics ours).

But he goes on to describe a full scientific study involving 600 children, split into three age groups, which would be completed in about a year's time. In an interview with WDDTY, he said this would be the first proper scientific study into adverse reactions.

And while the DoH was assuring the British public of the safety of the vaccine, they were informing doctors in a privately circulated letter that incidents of arthritis could be 11 per cent as a result of the vaccine.

And while they have been confidently telling British journalists that nobody has died as a result of the vaccine, even the conservative BMJ admits to at least eight deaths since 1988 (BMJ, 24 September 1994). About 100 families whose children have either died or suffered serious injury following the MMR vaccine (the mumps element has been withdrawn for the current campaign) have won legal aid to investigate a multi million pound claim for compensation.

The whole exercise has been dismissed by Dr Richard Nicholson, editor of Bulletin of Medical Ethics, as "an experiment on our children that breaches government guidelines" (The Times, 3 November 1994).