First central nervous system demyelination and hepatitis B vaccination: a pilot case control study.

Background: Central nervous system (CNS) demyelinating episodes have been d escribed following numerous vaccines but there is no definite conclusion ab out a causal relationship. Recently, in France, in the context of an Expand ed Program on immunization, several cases of CNS demyelination have been ob served following injection of recombinant hepatitis B (HB) vaccine, leading to great concern. Methods: We performed a hospital-based case-control study of 121 patients w ith a first episode of CNS demyelination occuring between July 1993 and Dec ember 1995 and 121 age and sex matched controls seen in the same period. Da ta on vaccinations history of cases and controls were collected by a postal questionnaire and confirmed by a phone interview. Results: Adjusted odds ratio (OR) obtained from conditional logistic regres sion between a first episode of CNS demyelination and any vaccination were equal to 1.4 (95 p. 100 Cl 0.5-4.3) for an exposure within the 60 previous days and 2.1 (95 p. 100 Cl 0.7-6.0) for an exposure within the 61-180 previ ous days. Similar results were found for HE vaccine exposure within the 60 previous days (adjusted OR = 1.7, 95 p. 100 Cl 0.5-6.3) or within the 61 to 180 previous days (adjusted OR = 1.5, 95 p. 100 Cl 0.5-5,3). Conclusion: These findings did not permit to exclude confidently an associa tion between HE vaccine and the occurrence of a first CNS demyelinating epi sode.