Reuters Health Information (2008-09-26): Engerix B vaccine may increase the risk of multiple sclerosis in children
Engerix B vaccine may increase the risk of multiple sclerosis in children
Last Updated: 2008-09-26 16:52:35 -0400 (Reuters Health)
NEW YORK (Reuters Health) - Although most hepatitis B vaccines do not seem to increase the risk of multiple sclerosis in children, use of one particular brand -- Engerix B (GlaxoSmithKline) -- may, according to findings from a study conducted in France.
In the study reported in the October 8th online issue of Neurology, the odds ratio for Engerix B exposure was 2.77 among children with MS compared to an unaffected control group.
Prior reports have suggested a link between hepatitis B vaccine exposure and central nervous system (CNS) inflammatory demyelination, including multiple sclerosis as well as acute disseminated encephalomyelitis and transverse myelitis. In general, however, findings from epidemiologic studies have not supported an association.
The focus of the current case-control study was on the neurologic effects of hepatitis B vaccination in children, since most of the prior investigations involved adults only, lead author Dr. Yann Mikaeloff, from Assistance Publique-Hopitaux de Paris, and colleagues note.
Case patients included 349 children with a first episode of CNS inflammatory demyelination between 1994 and 2003. Each subject was matched to up to 12 controls by age, gender, and geographic location.
In the overall analysis, hepatitis B vaccination did not increase the risk of CNS inflammatory demyelination.
However, when the analysis was confined to vaccine-compliant subjects, vaccine exposure more than 3 years prior to the index date was linked to an elevated risk (OR = 1.50). Further analysis showed that this association was mostly driven by the risk seen with Engerix B use (OR = 1.74).
Vaccine exposure more than 3 years before the index date was tied to a 2.12-fold increased risk of confirmed multiple sclerosis. Once again, however, this was mostly accounted for by Engerix B use (OR = 2.77).
As to why one brand of hepatitis B vaccine is safe, while another may not be, the authors offer two possible explanations: "1) each vaccine uses a different section of the HBs antigen and some protein fragments produced by yeasts may induce molecular mimicry while others do not; 2) the production process varies by brand and differences in yeast protein content may be crucial if yeast protein may trigger autoimmune reactions."
The packaging insert (December 2006) for Engerix B mentions reports of patients with multiple sclerosis who experience exacerbations following use of the vaccine, but it points out that causality has not been established. The insert also notes new cases of multiple sclerosis and transverse myelitis that occurred after vaccination and were identified during postmarketing surveillance.