VACCINATION IN PATIENTS WITH CIDP AND GBS.
Gareth J. Parry, M.B., Ch.B, F.R.A.C.P.
Professor of Neurology, University of Minnesota, U.S.A.
One of the most frequently asked questions from patients with GBS and
CIDP is whether they should avoid vaccinations, particularly influenza
vaccination. The question is a difficult one because there is so little data
on which to base the answer. I will briefly review the issues and try to
provide some guidelines but, as with so much in medicine, the decision is
a personal one that each patient must make, based on their best analysis
of the risks and benefits. This is my personal approach based on my best
interpretation of the available data; there is no strong consensus amongst
doctors in general or even amongst neurologists with a specific expertise
in GBS and CIDP.
Both GBS and CIDP are believed to be auto-immune diseases. These are
diseases that result from the body’s immune system attacking certain
components of the body. The immune system is designed to recognize
and eliminate attackers from outside the body such as viruses and
bacteria. It usually recognizes the body as “self” and does not react
against itself. However, it may become confused, resulting in a failure to
recognize specific body components, leading to an attack on itself. There
are many examples of auto-immune diseases including some types of
diabetes, rheumatoid arthritis, many skin diseases, some thyroid diseases
and many others. In GBS and CIDP, the component of the body that is
attacked is predominantly myelin, the lining of the nerve fibers that
provides insulation, although in some types there is an attack on the axon,
the nerve cable that transmits the electrical impulses (“axonal” GBS).
When the insulation is damaged a short circuit develops, the nerve fibers
cannot transmit their electrical signals to the muscles and paralysis
develops. The factors that result in this confusion of the immune system
are poorly understood. However, in some diseases we know that
infections or vaccinations can act as the trigger that somehow results in
an auto-immune attack. For example, about 70% of cases of GBS arise
following an identified antecedent event, usually an infection. The
relationship between CIDP and antecedent infections is less well
established. This is probably because the disease does not evolve as
rapidly as GBS and it is difficult to be certain exactly when it began and
therefore it is difficult to remember whether there was a specific
antecedent event. However, once CIDP is established we know that
infections or vaccinations can cause the disease to deteriorate.
Development of GBS following vaccination is remarkably uncommon.
The most highly publicized occurrence followed the influenza
vaccination program in the United States in 1976. In anticipation of a
potentially severe form of influenza (known as the swine influenza)
arriving in the U.S. that year President Ford ordered a national
vaccination program. Approximately 50 million people received the
vaccine and the incidence of GBS following that vaccination was more
than 20 times the expected incidence or the incidence in non-vaccinated
individuals. However, the risk seems to have been attached to that
specific vaccine. Prior to 1976 there had been only three cases of GBS
following influenza vaccination despite very widespread vaccination
programs and there has been no increase in the expected number of GBS
cases following subsequent influenza vaccination programs, even though
other vaccines have contained the swine ‘flu virus. Nor is there an
established risk of developing GBS following other vaccinations. There
has been a suggestion that one polio vaccination program in Finland was
associated with a slight increase in the number of GBS cases. Similarly,
there have been isolated reports of GBS following many other vaccines
but there has been no consistent relationship that would indicate a
predictable occurrence.
All of this information pertains to populations who have never had GBS;
i.e., these studies have looked at the incidence of GBS following
vaccination in normal populations. A related issue is whether people who
have recovered from GBS are at increased risk from vaccination.
Recurrent attacks of GBS, although rare, do occur and have been
described following vaccines, including influenza vaccines. Recurrence
of GBS may also occur following infections such as influenza. In any
given individual, the risk of developing another attack of GBS is probably
no greater than developing the first attack; i.e., having had GBS probably
does not make it more likely that an individual will have a second attack.
In patients with CIDP there is probably a greater risk that vaccinations of
any kind will produce a relapse of their disease. On the other hand, the
relapse is seldom severe; there may be a minor increase in numbness and
tingling or weakness but almost never life threatening problems such as
breathing or swallowing difficulties. Furthermore, the relapses are
usually responsive to standard CIDP treatment.
It is important to remember that the risk of developing new GBS, having
a recurrence of GBS or developing a relapse of CIDP are all considerably
greater following an infectious illness such as influenza than it is after
vaccination. Thus, by preventing the infection, vaccinations may actually
reduce the risk of one of these undesirable outcomes. For many diseases,
such as polio, typhoid, tetanus, rabies and others, the result of getting the
disease is so devastating that it is easy to recommend the vaccine, even if
it does cause GBS or CIDP. It is with the less severe diseases such as
influenza that the difficulties arise. Furthermore, most of the conditions
mentioned above require only a single vaccination in a life time while
influenza vaccines are recommended each year.
In making the decision about whether an individual who has had GBS
should receive the influenza vaccine (or any other vaccine for that matter)
I ask the following questions:1. Was the initial attack of GBS triggered by an influenza vaccine?
2. Was the initial attack of GBS triggered by influenza?
3. Is the individual at increased risk of significant complications of
influenza? This includes individuals with chronic respiratory disease
such as asthma, chronic bronchitis or emphysema, people over the age
of 70 years and people with other serious chronic diseases.
If the answer to either of the first two questions is affirmative while the
third is negative then the risk of the vaccine, although very small, may
outweigh any benefit. If the answer to the third question is affirmative
while the first two are negative then the benefit of the vaccination clearly
outweighs the slight risk that it will cause a recurrence of the GBS or
relapse of CIDP. If all three are affirmative then I usually still
recommend vaccination but certainly emphasize to the patient the
potential risk.