Possible Risk of CNS Demyelination With Hepatitis B Vaccine Requires Further Study
Hepatitis B vaccination generally does not increase the risk of pediatric CNS demyelinating diseases—like multiple sclerosis—in the short or long term; however, the Engerix B vaccine (GlaxoSmithKline) brand may, in the long term. These conclusions are based on a population-based, case-control study conducted in France, which was published online this week in Neurology. The investigators stress that their results require confirmation.
By matching 349 pediatric cases of clinical CNS demyelination—either single episodes* without relapse or MS—to 2941 controls (median control no. per case, 9), investigators calculated an adjusted odds ratio of 0.74 (95% CI: 0.54, 1.02) for an index episode of demyelination within a 3-year period of vaccination. Similar results were obtained when assessing more detailed time periods, number of hepatitis B vaccines received, and vaccine brand last received.
General rates of hepatitis B vaccination were similar in the case and control groups (24.4% and 27.3%, respectively). Notably a family history of MS was significantly higher in the case cohort (2.3% vs 1.1% in controls; P < .05); but calculated odds ratios were not significantly different when cases with a family history were excluded from analysis.
When considering cases and controls that were compliant with vaccine guidelines, exposure to Engerix B vaccine more than 3 years before the index episode was associated with an increased risk of CNS demyelination (adjusted OR, 1.74; 95% CI: 0.93, 2.43), and particularly MS (adjusted OR, 2.77; 95% CI: 1.23, 6.24). A trend toward an increased risk of CNS demyelination 3 years from the time of exposure to the GenHevac B vaccine (sanofi-aventis) was also observed in vaccine-compliant cases (adjusted OR, 1.50; 95% CI: 0.71, 3.17).
Other vaccines assessed in the study, which was supported by the Société Française de Neuropédiatrie and the French Ministry of Health, included HBVax (Vabiotech), Twinrix (GSK), and Recombivax (Merck). The authors propose that risk differences among vaccine brands may be due to the particular section of the hepatitis B surface antigen (HBsAg) used or variable reactions to yeast proteins (HBsAg is produced in yeast cells).
The prevalence of pediatric CNS demyelinating disorders is not well defined, but it is estimated that 12,000-22,000 people (2.7%-5.0%) living with MS in the United States or Canada received a diagnosis before the age of 16 years.
CNS = central nervous system.
* Single episodes of demyelination (n = 198) included acute disseminated encephalomyelitis (ADEM), optic neuritis, transverse myelitis, and brainstem dysfunction. Cases were matched to controls for age, sex, and area of residence.
