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MMR vaccine linked to bleeding disorder

February 20, 2001

The measles, mumps, and rubella vaccine is linked to a bleeding disorder,
called idiopathic thrombocytopenic purpura (ITP) in children, finds a study
in Archives of Disease in Childhood.

The disorder is caused by a shortage of platelets, the cells that give
blood its "stickiness," and is characterised by bleeding under the skin.
Around one in 10,000 people has the condition. In children, it is often
preceded by a viral infection.

The researchers, from the Public Health Laboratory Service and the Royal
Free Hospital, London, analysed records on hospital admissions for ITP .
The records included all children under the age of 5 admitted within six
weeks of MMR vaccination in the South East Thames and North East Thames
regions between October 1991 and September 1994.

There were 28 admissions for 21 children up to the age of 2 who had been
vaccinated with MMR. Of these, nine children had been admitted within six
weeks; none had had ITP before. The remainder involved cases that fell
outside the time period or who had been re-admitted at intervals of up to
five months.

Combining data from a previously published study, the authors calculated
that two out of every three cases of ITP in the six weeks after
immunisation are caused by MMR. One in every 22,300 MMR vaccinations will
result in admission to hospital for ITP, they say. There are as yet no data
on booster dose and the risk of ITP.

The children whose illness was associated with MMR tended to have milder
symptoms and spent less time in hospital than those whose ITP was not
associated with the vaccine. Children who had already had ITP were at no
greater risk of recurrence as a result of the vaccination, the study
showed.

Institute of Physics