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Risk of febrile seizure after MMR vaccine "slight"

27 July, 2004

The risk of a
child having a febrile seizure after receiving the MMR (measles, mumps
and rubella) vaccination is described in new research as "slight" and
no link can be found between the MMR vaccine and the development of

Researchers at Aarhus University, writing in the Journal of the American Medical Association,
studied over 535,000 children born in Denmark between 1991 and 1998. A
total of 439,251 children (82 per cent) received MMR vaccinations and
17,986 children developed febrile seizures at least once; 973 of these
febrile seizures occurred within two weeks of MMR vaccination.

risk of febrile seizures increased during the two weeks following MMR
vaccination (nearly three time as likely) however after that period
there appeared no increased risk of febrile seizures compared to the
risk for non-vaccinated children.

children aged between 15 to 17 months, 1.6 children per 1000 had a
febrile seizure within two weeks of the inoculation. The risk was
slightly higher for children whose siblings had a history of febrile
seizures (3.97 per 1000) and for children who themselves had a history
of febrile seizures prior to the vaccination, the risk was 19.47 per
1000 (around one child in 20).

who had febrile seizures following the MMR vaccination had a slightly
increased rate of further febrile seizures but the researchers could
find no increased risk of these children developing epilepsy.

Lead author Dr Mogens Vestergaard emphasises:

vaccination is an effective health intervention and the transient
increased rate of febrile seizures was restricted to two weeks
following vaccination."