transverse myelitis after vaccination against hepatitis B. The timing of the rechallenge appears to be a second episode, but the 1-month time frame between the two episodes is not sufficient to determine if the symptoms represent one or two episodes. A patient must return to baseline or be stable for at least 6 weeks before a new episode is recorded. Furthermore, no immunology indicating an enhancement of a proinflammatory response linked to the vaccine is presented.

Autoantibodies, T cells, and molecular mimicry may contribute to the symptoms of transverse myelitis; however, the publications did not provide evidence linking these mechanisms to hepatitis B vaccine.

The committee assesses the mechanistic evidence regarding an association between hepatitis B vaccine and transverse myelitis as weak based on one case.

Causality Conclusion

Conclusion 8.5: The evidence is inadequate to accept or reject a causal relation between hepatitis B vaccine and transverse myelitis.

OPTIC NEURITIS

Epidemiologic Evidence

The committee reviewed three studies to evaluate the risk of optic neuritis in adults after the administration of hepatitis B vaccine. One study (Geier and Geier, 2005) was not considered in the weight of epidemiologic evidence because it provided data from a passive surveillance system and lacked an unvaccinated comparison population.

The two remaining controlled studies (DeStefano et al., 2003; Payne et al., 2006) were included in the weight of epidemiologic evidence and are described below.

DeStefano et al. (2003) conducted a case-control study to evaluate the association between hepatitis B vaccination and optic neuritis using data from three health maintenance organizations (HMOs) participating in the Vaccine Safety Datalink (VSD). The optic neuritis analysis included 108 cases and 228 controls. The cases had a documented physician’s diagnosis from 1995 through 1999, and were matched to controls from the HMO on date of birth (within 1 year) and sex. The authors evaluated the date of disease onset using data described in the medical record or reported in the telephone interview. The immunization status was obtained from vaccination records, medical records, and telephone interviews. The study had high rates of self-reported vaccinations from outside the HMO system (51 percent of cases and 50 percent of controls) that could not be verified,



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