Other Potential Serious Side Effects
The notes below are from “The Vaccine Book
Encephalitis / Encephalopathy
Rarely, a baby will register a high fever and scream intensely, alternating with lethargy for several hours and possibly days. This reaction is thought to be due to swelling and inflammation of the brain, the medical term for “encephalitis.” Virtually all infants with an encephalitis reaction recover without any problems. Unfortunately, a small percentage of cases will progress to encephalopathy, during which the brain actually suffers some permanent damage. We don’t know for sure if the reaction is caused by vaccination or if it’s coincidental. It seemed to be most commonly associated with the old DTP vaccine, which we no longer use in the United States. The MMR and all tetanus-containing vaccines (according to their product inserts) may also be linked to this reaction.
Subacute sclerosing panencephalitis (SSPE).
It is similar to encephalitis, but it’s more gradual and chronic. Brain function slowly deteriorates over many years. SSPE has various causes, including certain viral infections. We don’t know for sure that any vaccine causes it.