Dear Dr.K: I’ve never taken the flu shot because my father got Guillian-Barré syndrome from the 1976 swine flue vaccine. Now that I’m 50, I worry about getting really sick from influenza. Do you think I can take the flue shot?
In a word, “yes.”
For those readers who don’t know about Guillian-Barré, let me explain. Now that polio is almost non-existent, Guillian-Barré is the most common cause for acute paralysis worldwide. Even though fewer than 5 percent of affected people die, it still can be a very serious problem. Typically, the weakness (paralysis) starts in the peripheral muscles of the feet and hands and moves upward.
Most of the cases occur after a pre-existing respiratory tract infection or diarrheal illness. The single most common cause for Guillian-Barré is a G.I. bug caused by campylobacter jejuni (a bacteria known to be a main cause of bacterial food-borne disease in many developed countries). Other common pathogens capable of causing it are cytomagalo virus (an infection caused by a member of the herpes virus family); Epstein-Barr virus (which is very common and usually mild); varicella-zoster virus (chickenpox and shingles viruses), and mycoplasmas (stealthy bacteria that can cause acute and chronic diseases at multiple sites).
In 1976 there were a number of individuals who got Guillian-Barré after receiving the swine flu (H1N1) vaccine. Subsequent seasonal flu vaccines over the past 36 years have not been associated with this risk. In fact, in 2009, the National Institutes of Health and the Centers for Disease Control had some concern that the H1N1 vaccine that year might have the same potential as the 1976 H1N1 vaccine, but this turned out not to be the case.
The reason that an antecedent infection can trigger Guillian-Barré is because of a phenomenon called molecular mimicry. Lipooligosacchoride is a big word for a small molecule that is a major component of the myelin, which is the protective coating on our nerve fibers. Certain viruses and bacteria have the molecule in their outer membranes. When susceptible individuals who are infected mount an immune response to kill the infecting organism, they make antibodies against the lipooligosaccoride. Unfortunately, this also attacks the same molecule (molecular mimicry) found on the nerve sheaths.
Thus, the individuals’ nerves are attacked by their own immune system.
Luckily, there are modern immune therapies that can help slow and turn off this auto-immune attack, and thereby lessen the severity of the illness.