Tetanus vaccination and risk of multiple sclerosis - A systematic review

Objective: To conduct a systematic review on the association between tetanus vaccination and the risk of multiple sclerosis ( MS). Methods: The authors searched the databases Medline, LILACS, EMBASE, and Science Citation Index including the period 1966 to September 1, 2005. Eligible studies had to meet the following inclusion criteria: presentation of original data, case-control or cohort design, physician-confirmed diagnosis of MS as the outcome of interest, attempt to ascertain vaccinations in a period before the diagnosis, and report of an association measure between tetanus vaccination and incidence of MS, and its 95% CI or enough information to compute it. Study specific log ORs were weighted by the inverse of their variances to obtain a pooled estimate and its 95% CI. Results: The OR of MS associated with history of tetanus vaccination was 0.67 ( 95% CI: 0.55 to 0.81). There was little indication of heterogeneity of results across studies. Conclusion: Tetanus vaccination is associated with a lower risk of multiple sclerosis.