viernes, 23 de mayo de 2014

CDC - Hepatitis B and Multiple Sclerosis ( MS) - Vaccine Safety

CDC - Hepatitis B and Multiple Sclerosis ( MS) - Vaccine Safety

FAQs about Hepatitis B Vaccine (Hep B) and Multiple Sclerosis

Numerous studies have evaluated a possible relationship between hepatitis B vaccination and multiple sclerosis (MS). The weight of the available scientific evidence does not support the suggestion that hepatitis B vaccine causes or worsens MS.

What is multiple sclerosis (MS)?

Multiple sclerosis (MS) is a disease of the central nervous system characterized by the destruction of the myelin sheath surrounding neurons, resulting in the formation of plaques. Because they involve the destruction of the myelin sheath that covers nerve tissue, diseases such as MS are known as demyelinating diseases.
MS is a progressive and usually fluctuating disease with exacerbations (patients feeling worse) and remissions (patients feeling better) over many decades. In many patients with MS, permanent disability and even death can occur. The cause of MS is unknown. The most widely held hypothesis is that MS occurs in patients with a genetic susceptibility and is triggered by certain environmental factors.
MS is 3 times more common in women than men, with diagnoses usually made as young adults; however, it has been estimated that between 2 and 5% of cases begin before age 16. Since MS is not widely recognized as a childhood disorder, diagnosis is often missed or delayed. In addition, many of its symptoms are similar to those of other pediatric neurological conditions, leukodystrophies, and metabolic disorders. Diagnosis in childhood is difficult due to the lack of universally accepted diagnostic criteria.

Does hepatitis B vaccination cause MS?

Most published scientific studies do not support a causal relationship between hepatitis B vaccination and MS or other demyelinating diseases. Examples of this scientific evidence are as follows:
  • Extensive pre-licensure clinical trials did not document such an effect.
  • Hundreds of millions of people worldwide have received hepatitis B vaccine without developing MS or any other autoimmune disease. This finding provides important evidence as well as an appropriate framework for assessing this possible association--namely that if vaccination causes MS, it does so extremely rarely.
  • Due to the large number of vaccinations administered worldwide, surveillance systems in the United States, France, and elsewhere (Quast 1991) expect to receive reports of MS that are only temporally (by chance alone) associated with vaccines.
  • According to a study published in the Oct. 8, 2000 issue of Neurology (Mikaeloff, 2008), the majority of children vaccinated against hepatitis B are not at an increased risk of developing CNS inflammatory demyelination. 349 children with a first episode of acute CNS inflammatory demyelination before age 16 were matched to 2,941 healthy controls and evaluated for use of hepatitis B vaccination. When subjects were restricted to those compliant with vaccination, children who received a specific type of hepatitis B vaccine (Engerix B) more than 3 years earlier were found to have a slightly increased risk of having a confirmed diagnosis of MS. The findings in this paper cannot be taken as confirmation that the vaccine caused MS. Further studies are needed to confirm this observation, and then, if confirmed, to determine whether this is a causal relationship.
  • A study conducted in France from 1994 to 2003 (Mikaeloff, 2007) did not find a relationship between vaccination for hepatitis B and the development of childhood-onset multiple sclerosis. The 143 cases included children with onset of MS before age of 16 years. 1,122 control subjects were selected randomly from the general French population. The rate of a first episode of MS was not increased for hepatitis B vaccination.
  • A study was conducted using Vaccine Safety Datalink (VSD) project to assess the association between hepatitis B vaccination and demyelinating diseases such as MS among members of 3 large managed care organizations (MCO's) on the West Coast of the United States (Verstraeten, 2001). The study included 422 adult cases (people with demyelinating disease) and 921 matched controls (people of similar age, gender, and MCO status who did not have demyelinating disease). The researchers concluded that hepatitis B vaccination was not associated with demyelinating disease in the study population.
  • Ascherio and colleagues (2001) evaluated the possible association between hepatitis B vaccination and MS. The study included 192 women with MS and 645 controls. The authors concluded that there was no association between hepatitis B vaccination and MS.
  • A study was conducted in Europe to evaluate whether MS relapses were associated with receipt of hepatitis B, tetanus, or influenza vaccines (Confavreaux, 2001). The study included 643 individuals with relapsing MS. The researchers concluded that there was no evidence of an association between recent receipt of hepatitis B vaccine (or tetanus or influenza vaccination) and MS relapses.
  • Sadovnick and Scheifele (2000) investigated multiple sclerosis in 578,308 adolescents in British Columbia before and after hepatitis B vaccination programs were implemented. The authors found no evidence of a link between hepatitis B vaccination and multiple sclerosis or other demylenating disease.
  • An analysis of a U.S. pharmacy benefits management database did not find a statistically significant association between claims for hepatitis B vaccination and subsequent claims for treatment of CNS demyelinating disorders (Zipp, 1999).

What has been done to examine the suggested association between hepatitis B vaccine and neurological disorders?

CDC and the National Institutes of Health (NIH) asked the National Academy of Sciences, Institute of Medicine to establish an independent expert committee to review hypotheses about existing and emerging immunization safety concerns. The review will involve an assessment of factors such as the biologic mechanisms of the hypotheses, competing alternative hypotheses, as well as the available scientific evidence to date.
In 2002, the IOM reviewed the evidence of a possible causal association between hepatitis B vaccine and demyelinating neurological disorders, including MS in adults. The committee found that the epidemiological evidence does not support a causal relationship between hepatitis B vaccine in adults and multiple sclerosis.

Should I delay hepatitis B vaccination until more is known?

No. Results from studies that have examined the possible association between hepatitis B vaccination and MS are reassuring and support current recommendations for immunizing against hepatitis B. Concern regarding the alleged association between hepatitis B vaccination and MS must be weighed against the vaccine's ability to prevent risks associated with hepatitis B virus infection. For more information, visit Viral Hepatitis B.

What research has been conducted to look at the possible link between vaccines and autoimmune diseases?

CDC takes concerns about vaccines and immune system diseases and disorders very seriously. Researchers at CDC and elsewhere have conducted studies to examine the possible link between vaccines and autoimmune conditions like MS, diabetes, and asthma. These studies have been reassuring, providing no evidence to suggest a link between vaccines and autoimmune conditions.
As part of ongoing vaccine safety surveillance, CDC will continue to conduct research to examine the effects vaccines may have on the immune system.

Related Scientific Articles

Ascherio A, Zhang SM, Hernan MA, et al. Hepatitis B vaccination and the risk of multiple sclerosis.External Web Site IconNew England Journal of Medicine 2001;344(5):327–332.
Confavreux C, Suissa S, Saddier P et al. Vaccinations and the risk of relapse in multiple sclerosis.External Web Site IconNew England Journal of Medicine 2001;344(5):319–326.
DeStefano F, Weintraub ES, Chen RT. Hepatitis B vaccine and risk of multiple sclerosis [letter]External Web Site IconPharmacoepidemiology and Drug Safety 2007;16(6):705–707.
Fourrier A, Touze E, Alperovitch A, Begaud B. Association between hepatitis B vaccine and multiple sclerosis: a case-control study. Pharmacoepidemiology & Drug Safety 1999;8:S140–141.
Herrolen L, DeKeyser J, Ebinger G. Central nervous system demyelination after immunisation with recombinant hepatitis B vaccine.External Web Site Icon Lancet 1991;338(8776):1174–1175.
Lewis E, Shinefield HR, Woodruff BA, Black SB, DeStefano F, Chen RT, Ensor R. Safety of neonatal hepatitis B vaccine administration.External Web Site Icon Pediatric Infectious Disease Journal 2001;20: 10489-1054.
Mikaeloff Y, Caridade G, Rossier M, Suissa S, Tardieu M. Hepatitis B vaccination and the risk of childhood-onset multiple sclerosis. Archives of Pediatrics and Adolescent Medicine 2007: 161(12): 1214-15.
Niu MT, Rhodes P, Salive M, Davis DM, Black S, Shinefield H, Chen RT, Ellenberg SS. Comparative safety of two recombinant hepatitis B vaccines in children: data from the Vaccine Adverse Event Reporting System (VAERS) and Vaccine Safety Datalink (VSD).External Web Site Icon Journal of Clinical Epidemiology1998; 51(6):503-510.
Quast U, Herder C, Zwisler O. Vaccination of patients with encephalomyelitis disseminata.External Web Site Icon Vaccine1991;9(4):228–230.
Sadovnik AD, Scheifele DW. School-based hepatitis B vaccination programme and adolescent multiple sclerosis.External Web Site Icon Lancet 2000;355(9203):549–550.
Sturkenboom MCJM, Abenhaim L, Wolfson C, Roulet E, Heinzelf O, Gout O. Vaccinations, demyelination, and multiple sclerosis study (VDAMS). Pharmacoepidemiology & Drug Safety1999;8:S170–171.
Touzé E, Gout O, Verdier-Taillefer MH, Lyon-Caen O, Alpérovitch A. The first episode of central nervous system demyelinization and hepatitis B vaccination.External Web Site Icon Revue Neurologique2000;156(3):242–246.
Verstraeten T, DeStefano F, Jackson L, Benson P, Okoro C, Black S, Shinefield H., Mullooly J, Chen R.; VSD Team. Risk of demyelinating disease after hepatitis B vaccination—West Coast, United States, 1995–1999. Paper presented at the 50th Annual Epidemic Intelligence Service Conference, 2001, Atlanta GA.
Yu O, Bohlke K, Hanson CA, Delaney K, Rees TG, Zavitkovsky A, Ray P, Mullooly J, Black SB, Benson P, Thompson WW, Davis RL, Jackson LA. Hepatitis B vaccine and risk of autoimmune thyroid disease: a Vaccine Safety Datalink study.External Web Site Icon Pharmacoepidemiology and Drug Safety2007;16(7a):736-745.

Zipp F, Weil JG, Einhaupl KM. No increase in demyelinating diseases after hepatitis B vaccination.External Web Site IconNature Medicine 1999;5(9):964–965.

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