Vaccinations and the Risk of Relapse in Multiple Sclerosis

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ok great, we can all rest a little easier now that they've " proven " no link

between vax and ms. gee, thanks!!

The New England Journal of Medicine

February 1, 2001 (Volume 344, Number 5)

Vaccinations and the Risk of Relapse in Multiple Sclerosis

Confavreux C, Suissa S, Saddier P, et al.

N Engl J Med.

2001;344:319-326

Although the etiology of multiple sclerosis (MS) is unknown, a growing body

of evidence suggests an immunologic role in the pathogenesis of the disease.

Some have speculated that an appropriate " trigger " of the immune system may

set off a response that ultimately results in the onset of the disease or

relapse in those with the disease. There has been considerable controversy

over the possible impact of vaccinations on this process. Public concern was

heightened when new reports of onset or relapse of MS followed an extensive

immunization program against hepatitis B in France. The French government

took action in October 1998 and temporarily suspended the school-based

vaccination program. Confavreux and colleagues conducted a case-crossover

study to evaluate the short-term risk of relapse for patients with MS

following recent vaccinations. In the case-crossover design, the patients

served as their own controls with data used from different points in time.

The relative risk of relapse was measured by comparing the exposure to the

vaccination in the period immediately preceding the index relapse (the risk

period) with that during control periods that were not followed by a relapse.

A relapse was defined as an occurrence, reappearance, or worsening of

symptoms of neurologic dysfunction that lasted more than 24 hours.Patients

who were eligible for the study were initially identified through the

European Database for Multiple Sclerosis (EDMUS). All subjects had been given

a definite or probable diagnosis of MS and had a relapse between 1993 and

1997. The index relapse was the first relapse confirmed by a visit to a

neurologist and preceded by a relapse-free period of at least 12 months. A

standardized telephone questionnaire was used to obtain information regarding

vaccination history during 1992 through 1997. The standard 6-year period

started 1 year before the period of interest for index relapses. The

interviewer was unaware which relapse was of interest and the patient had no

information concerning the study hypothesis or the date of the relapse of

interest. Exposure to a vaccination in the 2-month risk period immediately

preceding the relapse was compared with that in the 4 previous 2-month

control periods for the calculation of relative risks. Conditional logistic

regression was used for the estimations.Of the 643 interviewed patients with

relapses of MS, 15% reported receiving a vaccination during the preceding 12

months. The vaccination history was confirmed in 94% of the reports. Of all

the patients, 2.3% had been vaccinated during the preceding 2-month risk

period compared with 2.8% to 4.0% who were vaccinated during 1 or more of the

4 control periods. The relative risk of relapse associated with vaccination

exposure during the previous 2 months was 0.71 (95% confidence interval [CI],

0.40-1.26). The type of vaccination (tetanus, hepatitis B, or influenza) did

not influence the risk of relapse. Notably, another study published in the

same journal issue by Ascherio and colleagues,[1] reported no association

between hepatitis B vaccination and the development of MS. The results of the

2 studies should provide some reassurance to the healthcare community and

patients regarding the risk of MS exacerbation or onset in association with

vaccinations.

References

Ascherio A, Zhang SM, Hernán MA, et al. Hepatitis B vaccination and the risk

of multiple sclerosis. N Engl J Med. 2001;344:327-332. <A

HREF= " http://www.nejm.org/content/2001/0344/0005/0327.asp " >

http://www.nejm.org/content/2001/0344/0005/0327.asp</A> <A

HREF= " http://www.nejm.org/content/2001/0344/0005/0319.asp " >Abstract</A>