Seizure Risk Higher With 4-Vaccine Shot

Children who receive a shot containing four vaccines have a greater risk of a febrile seizure than children who get two shots, a new study finds. But the risk is still very small — fewer than 1 seizure out of 1,000 doses. A febrile seizure is caused by a high fever or other sudden increase in body temperature. Children may become stiff or have jerky movements. They may lose consciousness. The new study looked at records of 459,000 children. All had received a vaccine for measles between ages 12 and 23 months. Some got the MMR shot, which includes vaccine for measles, mumps and rubella. They received a shot for varicella (chickenpox) at the same visit. The other children got the MMRV shot, which includes varicella in the same shot. For every 2,300 doses of MMRV given, there was 1 extra seizure compared with the rate for the MMR shot.