Can Immunization Be a Risk Factor for Multiple Sclerosis?

Immunizations rarely result in delayed hypersensitivity reactions, which may manifest as neurological disease. The link between immunization and a chronic demyelinating disease such as multiple sclerosis (MS) has not been conclusively proven. Case reports suggest a temporal association but do not prove causation due to recall and publication biases.

To examine this possible association, researchers conducted a case-control study using data from more than 3 million members of the Kaiser Permanente Southern California healthcare system. Researchers ascertained all cases of MS and demyelinating disease by searching ICD9 codes and confirming the diagnoses using medical records. Five controls were selected for each case. The researchers obtained …