Monday, August 23, 2010

Lancet: The Influenza - Guillain Barré Syndrome Connection



# 4829



For more than 3 decades the public’s image of influenza vaccines has been tainted by memories of the 1976 swine flu shot which was associated with an unexpected increase in the number of GBS (Guillain Barré Syndrome) cases.


I’ve repeated the story, and my minor role in it, many times before.  But for those interested in the history of the 1976 Swine Flu program you may wish to read  Deja Flu, All Over Again


In the 34 intervening years, however, surveillance systems have failed to find any convincing evidence linking the neurological disorder with the influenza vaccine.  


It is believed that if such a link does exist, that it occurs so infrequently as to be practically undetectable.  The statistic of 1 case out of 1 million vaccinations is often mentioned, but no one really knows.  


But we do know that GBS  most often occurs after a viral or bacterial infection, and here in the United States, can be expected to strike several thousand people each year.


The CDC has a fact sheet on GBS, which states in part:


Fact Sheet: Guillain-Barré Syndrome (GBS)

December 15, 2009, 3:30 PM ET

Guillain-Barré syndrome is rare
Guillain-Barré syndrome (GBS) is a rare disorder in which a person’s own immune system damages the nerves, causing muscle weakness and sometimes paralysis. GBS can cause symptoms that last for as little as a few weeks, or go on for several months. Most people recover fully from GBS, but some people have nerve damage that does not go away. In rare cases, people have died of GBS, usually from not being able to breathe due to weakness of their breathing muscles.
GBS may have several causes
While it is not fully known what causes GBS, it is known that about two-thirds of people who get GBS do so several days or weeks after they have been sick with diarrhea or a lung or sinus illness. An infection with the bacteria Campylobacter jejuni, which can cause diarrhea, is one of the most common illnesses linked to GBS. Although rare, people can also get GBS after having the flu or other infections such as Epstein Barr virus. Except for the swine flu vaccine used in 1976, no other flu vaccines have been clearly linked to GBS.


Despite the warnings of the anti-vaccine crowd - many of whom predicted massive deaths and injury from the shot -  the evidence has shown that the pandemic shot given here in the United States and in Canada was extraordinarily safe.


A few blogs on the safety of the 2009 H1N1 vaccine include:


MMRW: Surveillance For GBS Among H1N1 Vaccine Recipients
What A Difference Three Decades Makes
VAERS Vaccine Safety Report


All of which brings us to a Lancet article (hat tip @jnwilliams76) that, alas, is behind a pay wall. A pity since I’d love to see their data.


What we do have access to is the abstract (below - slightly reformatted for readability) where the authors state that the risks of contracting GBS from the vaccine appear to be minor compared to the risks of developing GBS from catching the flu virus itself.



The Lancet Infectious Diseases, Volume 10, Issue 9, Pages 643 - 651, September 2010


Guillain-Barré syndrome after exposure to influenza virus

Original Text

Helmar C Lehmann MD, Prof Hans-Peter Hartung MD, Prof Bernd C Kieseier MD , Prof Richard AC Hughes MD


Guillain-Barré syndrome (GBS) is an acute, acquired, monophasic autoimmune disorder of peripheral nerves that develops in susceptible individuals after infection and, in rare cases, after immunisation. Exposure to influenza via infection or vaccination has been associated with GBS.


We review the relation between GBS and these routes of exposure. Epidemiological studies have shown that, except for the 1976 US national immunisation programme against swine-origin influenza A H1N1 subtype A/NJ/76, influenza vaccine has probably not caused GBS or, if it has, rates have been extremely low (less than one case per million vaccine recipients).


By contrast, influenza-like illnesses seem to be relevant triggering events for GBS. The concerns about the risk of inducing GBS in mass immunisation programmes against H1N1 2009 do not, therefore, seem justified by the available epidemiological data.


However, the experiences from the 1976 swine flu vaccination programme emphasise the importance for active and passive surveillance to monitor vaccine safety.