Vaccination against tetanus may offer protection against the development of multiple sclerosis (MS), according to a new study from Boston-based researchers.

Dr. Miguel A. Hernan and colleagues from Harvard School of Public Health pooled data from nine studies published between 1966 and 2005 that looked at the association between tetanus vaccination and MS risk. Analyses centered on a total of 963 MS cases and 3126 controls.

They found that a history of having been immunized against tetanus was associated with a 33 percent decrease in risk of MS.

The results of the current meta-analysis suggest that tetanus vaccination may prevent or delay the development of MS. The investigators call for further epidemiologic research to assess the role of timing of immunization and the number of doses associated with this protective effect.

The hypothesis that tetanus immunity may protect against MS is supported by the findings of two recent prospective studies, Hernan and colleagues note in a report in the journal Neurology.

The biologic mechanism by which the tetanus vaccination may protect against MS is unclear, according to the authors. They note, however, that vaccination with tetanus toxoid may shift the T helper cell immune response from a proinflammatory Th1 response to an anti-inflammatory Th2 response.

Immunizing with the tetanus toxoid “could be a promising approach for the treatment and prevention of MS and other Th1 cell mediated autoimmune disorders,” the clinicians charge.

SOURCE: Neurology July 25, 2006.