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3e.8 What are some of the risks of the hepatitis B vaccine?




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This article is from the Childhood Vaccinations FAQ, by Lynn Gazis-Sax lynng@alsirat.com with numerous contributions by others.

3e.8 What are some of the risks of the hepatitis B vaccine?

Hepatitis B has traditionally been considered one of the safest and
least reactogenic vaccines:

"During clinical studies involving over 10,000 individuals distributed
over all age groups, no serious adverse reactions attributable to
vaccine administration were reported." (PDR, 1993) The most common
adverse reactions were injection site soreness (22%) and fatigue
(14%). A longer list of adverse reactions can be found in the
PDR. "Update: Vaccine Side Effects, Adverse Reactions,
Contraindications, and Precautions," published by ACIP in 1996,
reported that VAERS data showed a low rate of anaphylaxis
(approximately one event per 600,000 doses given).

More recently, controversy has been aroused by news reports,
particularly in France, of new or reactivated cases of multiple
sclerosis, and other demyelinating disorders, within two to three
months following administration of hepatitis B vaccine. Critics argue
that the risk is too high for a vaccine routinely given to children
not directly at much risk for hepatitis B. Supporters of vaccination
argue that, given the demonstrated risk of liver cancer and cirrhosis
of the liver from hepatitis B, effective vaccination programs should
not be abandoned for a hypothetical risk that the vaccine might in
rare cases lead to multiple sclerosis and other demyelinating
diseases.


As is the case in other controversies about vaccination risks, part of
the difficulty is assessing just what effect the hepatitis B vaccine
may have on demyelinating diseases. Multiple sclerosis is, in some
countries, the most common neurological disease of young
adulthood. Though most commonly reported between 20 and 40, it can be
reported at younger and older ages, and, given near universal
vaccination of pre-adolescents, some cases of MS are to be expected,
simply by chance, in proximity to vaccination. Since the incidence of
cases of multiple sclerosis attributed to the vaccine, in France and
elsewhere, is less than the number already expected for the age range
in question, statistical analysis is required, to determine whether
the risk of MS and other demyelinating diseases is in fact higher in
populations vaccinated for hepatitis B, and, if so, what the risk
might be.

Several studies have been carried out, to date, to assess this risk,
and more are ongoing.

ACIP reported, in 1996, that evidence was inadequate to establish or
reject a causal relationship between hepatitis B vaccine and
demyelinating diseases of the central nervous system.

The French National Drug Surveillance Committee studied people who
received more than 60 million doses of hepatitis B vaccine between
1989 and 1997, and found that the prevalence of neurological disease,
including MS, was actually lower in this group than in the general
population.

Three French studies, prompted by reports of MS, showed a slightly
increased relative risk in the vaccinated population, but not one
which was statistically significant. In response to this, the French
government required a risk-benefit analysis. The risk-benefit analysis
did not attempt to determine whether the hepatitis B vaccine in fact
causes MS or other demyelinating diseases, but rather to use the
largest possible risks which could be derived from the studies which
had been done, and weigh these against the expected benefits of
hepatitis B vaccine (with both being assessed in a statistical,
quantititive fashion). This study concluded that, though it isn't
possible to determine yet whether there is an association between the
hepatitis B vaccine and MS, the benefits of the vaccine for a given
vaccinated pre-adolescent cohort would clearly outweigh the risks.

In Canada, the Alberta Ministry of Health reported that a preliminary
examination of hospital admission data between 1975 and 1995 suggests
that the introduction of the hepatitis B vaccine in the mid-1980s has
not been marked by an increase in the incidence of multiple sclerosis.

The World Health Organization Viral Hepatitis Prevention Board (VHPB)
assembled experts, on September 28-30, 1998, to review the
epidemiology and current understanding of MS. This group examined data
on the epidemiology of hepatitis B, the epidemiology of multiple
sclerosis, from national reporting systems in the US, Italy, and
Canada, from one active pediatric surveillance system in Canada, from
industry post-marketing surveillance and clinical data, from published
studies of hepatitis B safety, and from preliminary reports of a small
number of unpublished epidemiological studies in the US, France, and
the UK. They tried to decide between three hypotheses for explaining
the relationship between the hepatitis B vaccine and MS: 1)
coincidence, 2) "triggering," in which an illness which would have
occurred anyway was unmasked by the vaccine, or 3) a true causal
relationship.

Evidence for the hypothesis of coincidence included the lack of any
statistically significant association with MS to date, and the fact
that age and sex distributions of reported adverse events resemble age
and sex distributions seen before the vaccine. Evidence in support of
an increased risk as precipitating factor was the fact that some
studies showed slightly increased risk of MS, though not to a
statistically significant degree. Evidence against was that another
study showed no increased risk. The group concluded that the evidence
for an association between the hepatitis B vaccine and MS was weak,
and did not meet the criterion for causality.

Response to this data has shown a rare divergence in public health
policies. The French National Network of Public Health, while still
recommending the vaccine as useful to pre-adolescents, concluded that,
because of differences in individual risk for hepatitis B and for side
effects of the vaccine and "the need for a medical consultation
including the personal and family history," the vaccination program
for pre-teens in the schools would be suspended. This suspension was
announced on October 1,
1998. Public health departments in several other countries, along with
the World Health Organization, criticized the French
government for making a decision based more on politics than on the
actual risks, and reaffirmed existing vaccination policies. The US
Congress held hearings on the subject, while the CDC affirmed that
"The scientific evidence to date does not support hepatitis B
vaccination causing MS or other demyelinating diseases."
(http://www.cdc.gov/nip/vacsafe/fs/qhepb.htm#7) Several organizations
concerned with hepatitis B and multiple sclerosis, in the US and
Canada, came out with statements supporting continued hepatitis B
vaccination.

As I write this section of the FAQ, the CDC reports that at least six
research projects are underway, in the US, France, and the UK, to
examine what relationship, if any, exists between the hepatitis B
vaccine and multiple sclerosis. In the meantime, most countries are
continuing to recommend universal hepatitis B vaccination for infants
and for pre-teens who have not already been vaccinated.

 

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