# 4987
The headline from yesterday’s Daily Mail proclaims:
Experts admit swine flu jab `may cause’ deadly nerve disease
By Jo Macfarlane
Last updated at 11:24 PM on 16th October 2010
And the lede reads:
Health chiefs have for the first time acknowledged that the swine flu jab may be linked to an increased risk of developing a deadly nerve condition.
Breaking news? Well, hardly.
In fact, I’m having a hard time finding anything `new’ in this story which states that experts from the UK’s Medicines and Healthcare products Regulatory Agency (MHRA) are looking at whether there might be a possible connection between last year’s swine flu shot and Guillain-Barre Syndrome.
According to this story, a recent report from the MHRA stated:
‘Given the uncertainties in the available information and as with seasonal flu vaccines, a slightly elevated risk of GBS following H1N1 vaccines cannot be ruled out. Epidemiological studies are ongoing to further assess this possible association.’
Apparently, this one statement –`a slightly elevated risk of GBS cannot be ruled out’. – is the basis for all this journalistic consternation.
According to this Daily Mail report, out of 6 MILLION swine flu shots given last year in the UK, 15 suspected cases of GBS were reported after vaccination.
- Missing from this report is the fact that every year, about 1500 people in the UK are diagnosed with GBS – most of whom never received the flu vaccine.
- No mention is made of the burden of deaths and/or hospitalizations in the UK from last year’s influenza pandemic.
- Also missing is the evidence that getting the flu is a far greater risk factor for developing GBS than is getting the flu shot (more on that later).
But I suppose including these factoids would just clutter up what is otherwise a perfectly good story, wouldn’t it?
First, a little about GBS from the UK’s Guillain-Barre Syndrome Support Group. (Note: CIDP (chronic inflammatory demyelinating poly[radiculo]neuropathy) is considered a related disease).
Who can get GBS and CIDP?
Anyone: young or old, male or female. The illnesses are neither hereditary nor contagious. GBS affects about 1500 people every year in the United Kingdom; the incidence of CIDP is perhaps one tenth that of GBS.
What causes GBS/CIDP?
This is a matter of much research. About sixty percent of patients suffer from a throat or intestinal infection, influenza or stress symptoms in the previous two weeks. These infections trigger an incorrect response in the immune system which attacks the nerves.
While the exact cause of GBS isn’t well understood, scientists have known for decades that it often appears following a respiratory, or intestinal infection.
In 1976, an increased incidence of GBS in the United States was associated with that year’s Swine Flu shot, but repeated studies have failed to establish a link between subsequent flu vaccines and GBS over the past three decades.
For those interested in learning more about the events of that year, I would direct you to my blog essay Deja Flu, All Over Again.
The CDC, along with many other public health agencies, accept that the flu vaccine might carry with it a very low risk of developing GBS. But most years the incidence is so low (perhaps 1 in 500,000 or 1 in a million) as to be nearly impossible to measure.
This from the CDC’s Guillain-Barré syndrome (GBS) Q&A page.
What causes GBS?
Many things can cause GBS; about two-thirds of people who develop GBS symptoms do so several days or weeks after they have been sick with diarrhea or a respiratory illness. Infection with the bacterium Campylobacter jejuni is one of the most common risk factors for GBS.
People also can develop GBS after having the flu or other infections (such as cytomegalovirus and Epstein Barr virus). On very rare occasions, they may develop GBS in the days or weeks after getting a vaccination.
According to the CDC, here in the United States the background rate of GBS runs from between 80 to 160 new cases per week – regardless of vaccination status.
While there is always some small risk involved in taking a vaccine, in the face of our yearly flu epidemic (or last year, a pandemic) I’ve always maintained that it is a risk worth taking.
No medicine, no drug, and no vaccine is 100% safe for 100% of the people that take it.
Even aspirin and NSAIDs – sold over the counter – contribute to thousands of hospitalizations and deaths each year. Penicillin, which has saved millions of lives over the years, can cause life threatening anaphylactic responses in some people.
All medicines are a double-edged sword.
That said, last year in excess of 12,000 Americans are believed to have died from the Swine flu, and the CDC estimates there were roughly 274,000 pandemic flu related hospitalizations.
A disproportionate number of those (90%) were under the age of 65.
Despite near-hysterical warnings over the safety of the pandemic vaccine, no deaths were attributed to the Swine flu shot (see CIDRAP VAERS study finds H1N1 vaccine safety similar to seasonal vaccines') and most reported side effects from the vaccine were minor, and temporary.
Only rarely did serious adverse reactions occur.
The truth is, the benefits of the flu shot far exceeded its risks.
As far as GBS is concerned . . . even if (and its a big `if’) vaccines were responsible for a handful of Guillain Barre cases last year . . . the flu almost certainly caused many more.
Two studies for you to ponder.
The first one comes from The American Journal of Epidemiology, and was published before the 2009 pandemic in September of 2008.
Investigation of the Temporal Association of Guillain-Barré Syndrome With Influenza Vaccine and Influenzalike Illness Using the United Kingdom General Practice Research Database
The entire study is available online, complete with graphs and charts, and supporting information. But the `money quote’ from the abstract reads:
The authors found no evidence of an increased risk of Guillain-Barré syndrome after seasonal influenza vaccine.
The finding of a greatly increased risk after influenzalike illness is consistent with anecdotal reports of a preceding respiratory illness in Guillain-Barré syndrome and has important implications for the risk/benefit assessment that would be carried out should pandemic vaccines be deployed in the future.
And second, a more recent study that I covered earlier this summer (see Lancet: The Influenza - Guillain Barré Syndrome Connection) that also found that influenza – not the flu shot – was a significant trigger for developing GBS.
The Lancet Infectious Diseases, Volume 10, Issue 9, Pages 643 - 651, September 2010
doi:10.1016/S1473-3099(10)70140-7
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
Summary
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.
It’s within the realm of possibility that over time we’ll discover that modern flu vaccines may be responsible for causing a small number of GBS cases each year. The evidence for that is scant right now, but as the MHRA stated, it can’t be ruled out.
The evidence, on the other hand, showing that influenza (and influenza-like) viruses can be a trigger for GBS is far greater.
If you want to reduce your (admittedly small) risk of developing GBS this winter, the good news is that getting the flu shot is a pretty good strategy.
But of course, those who get their vaccine knowledge from the `popular press’, instead of The Lancet or The American Journal of Epidemiology , are unlikely to know that.
