Does the flu vaccine cause Guillain-Barré syndrome or not?

urlGuillain-Barré syndrome (GBS) is a pretty scary condition. It starts with weakness and tingling in the extremities and can eventually leading to paralysis. Although most people recover in time, death can occur. Luckily, it’s a rare disease. It’s thought to result from an autoimmune process in which peripheral nerves are demyelinated and destroyed.

What causes GBS? Infections seem to be a major trigger. In about two-thirds of cases, the syndrome is preceded by either a gastrointestinal or respiratory infection. Campylobacter enteritis seems to be the most common trigger, but influenza, cytomegalovirus, Epstein-Barr virus, and HIV have all been implicated too. It appears that, in rare cases, these pathogens trigger the autoimmune cascade that leads to the diseases.

The 1976 H1N1 vaccine and GBS

Way back in 1976, researchers noticed something scary. 1976 was the year of the big swine flu epidemic scare. In February of that year, two army recruits at Fort Dix, in New Jersey, tested positive for swine flu. Researchers believed the strain they were infected with was similar to the one that had caused the 1918 flu pandemic that had killed millions. When they looked a little harder, they found that hundreds of other recruits at the base had been infected as well. Because these were not folks that had contact with pigs, it meant that the virus was spreading from person to person. Naturally, people were nervous. The government decided it would produce a vaccine against this strain and vaccinate as many people as possible, in order to head off what it feared might be a terrible pandemic.

Something strange happened though. Cases of GBS in people who had received the flu vaccine started cropping up. Hundreds of them. In 2009, The New York Times ran the story of Janet Kinny, a woman who developed GBS after receiving the shot in 1976. GBS put this young mother in the hospital for a month, paralyzed from the neck down. She recovered, but not everyone was so lucky. More than 30 of the people who developed GBS after getting a flu shot that year died. Epidemiologists spent a while debating whether or not this cluster was just a coincidence. In the end, most agreed that the shot really was associated with an increased risk of GBS. Researcher Lawrence Schonberger estimated that people who received the 1976 flu shot were roughly 7 times more likely to develop GBS than people who did not. For every 100,000 people vaccinated, approximately one got GBS. In December 1976, after having immunized more than 40 million people and failing to see evidence that the H1N1 pandemic was actually going to materialize, government officials called off the vaccination campaign due to the GBS risk.

Not surprisingly, people became wary of flu vaccines. Nobody wants to get GBS. A lot of work has been done over the years to try to clarify the risk that flu shots pose, but GBS is such a rare condition that it has been hard to put together studies large enough to shed light on this problem. Well, this year, three important studies on the flu vaccine and GBS came out. These were huge studies that each looked at millions of people, and they’ve provided a lot of insight into the relationship between vaccines and GBS.

2013: The year of gigantic flu shot/GBS studies

The first study appeared in Clinical Infectious Diseases. The authors mined data collected over 13 years (from 1994–2006) by Kaiser Permanente. Those of you from the West Coast know that Kaiser Permanente is a big insurer/hospital system with tons of clients. Using records for 3 million of patients, they were able to identify 415 confirmed cases of GBS. Sure enough, exactly two-thirds of these patients had suffered a respiratory and/or gastrointestinal illness in the 90 days preceding the onset of their GBS. But only 25 had received a vaccine of any kind in the 6 weeks prior to onset. In this study, GBS was NOT associated with getting a prior flu shot. However, the authors pointed out they could not rule out a very small increased risk of GBS; it’s always possible that with a larger sample size (i.e. more cases) they would have increased power to identify a small association.

Another even larger study appeared in the Lancet Infectious Diseases, and it, too, focused on seasonal flu vaccines. Carried out using the universal health care system records in Ontario, Canada, it was able to identify 2,831 incidents of GBS between the years of 1993 and 2011. The authors of this study found that the risk of developing GBS was roughly 50% higher in the six weeks following a seasonal flu shot, vs the risk experienced 9–42 weeks after. Thus, there really did seem to be a small, increased risk of GBS associated with seasonal flu shots. However, the authors found that actually GETTING the flu was a much bigger risk factor for GBS. In the six weeks after seeking medical help for the flu, the risk of GBS was roughly 16 times greater (vs 1.5 times for the shot) than in the weeks following the danger period. To put these findings in context: For every million people vaccinated with the flu shot, about 1 would get GBS, and for every million people who got the flu, 17 would get GBS.

The third study appeared in The Lancet, and it focused on the flu vaccine in one special year: 2009. You may remember that 2009 was the year of another H1N1 swine flu scare (and thus another H1N1 swine flu vaccine). So if any flu shot was linked to a greater risk of GBS, as in 1976, it seems like it would be this one. When focusing on this single year, researchers found an increase in GBS cases associated with the vaccine. Of the 23 million people who received the H1N1 vaccine and were included in the study, 54 developed GBS within 6 weeks of the shot. This works out to be about 1.6 extra GBS cases for every million people vaccinated. Thus, there WAS a slightly higher risk of GBS linked to the shot–but it was tiny. So tiny, the authors point out, that most studies of seasonal flu vaccines simply wouldn’t be large enough to detect the association. The sample size issue may well explain why the first study (based on the Kaiser Permanente data) did not identify an association between flu vaccines and GBS.

The take-home message: the extremely low risk of vaccine-related GBS is outweighed by the much higher risk of flu complications

So it appears that there is a small risk of GBS associated with flu vaccines. But, as flu researchers have been quick to point out, the risk associated with actually GETTING the flu is much higher. Poland and colleagues have posed a thought experiment in the Lancet on this subject. They point out that if everyone in the US had gotten the 2009 H1N1 vaccine, it’s estimated that 22 vaccine-related deaths would have occurred. But it everyone had gotten the H1N1 flu, 12,470 deaths would have occurred. Although the side-effects of a vaccine loom large in our minds, it’s important to put these risks in perspective: most vaccines prevent dangerous diseases, so foregoing a vaccine poses its own (often much greater) risks.

These modern studies still don’t explain exactly what happened in 1976. Why did that particular vaccine cause the syndrome at such a high rate (1 per 100,000 vs. 1 per 1,000,000 for modern vaccines)? Nobody knows. One explanation for the increased GBS risk is that the vaccine was contaminated with a bacterial trigger like Campylobacter.  Another explanation, which seems more plausible, is that something in the vaccine resembled nerve cells–so that when a recipient’s body mounted an attack against the vaccine, the attack might have hurt nerve cells as well. It would be comforting if, eventually, we could identify the problem.

13 thoughts on “Does the flu vaccine cause Guillain-Barré syndrome or not?

  1. Pingback: A side effect of the flu vaccine teaches us something new about narcolepsy | So much science, so little time

  2. Statistics for the relationship of GBS cases to flu shots are not reliable. My father-in-law in England contracted GBS a few weeks after receiving a flu shot. The hospital he was sent to appears to have had no experience with GBS. When the paralysis spread to his breathing during the night, he was unable to press his emergency buzzer, and was dead by the time nursing staff found him. The hospital simply recorded his death as being due to GBS. There was no mention of the flu shot he had previously. How many more times have hospitals failed to record the link of GBS cases with prior flu shots?

    • Individual case stories are compelling and occasionally tragic. The advantage of large studies like the Ontario study is that they can track who got flu shots and who got GBS in separate databases and create the correspondence whether the hospital reports it or not, so cases like your father-in-law would not be missed. No one is contending that we have proven that GBS never follows flu shots, but the data strongly suggests you are safer having a flu shot than risking having the flu.

  3. Yes, I believe the flu shot is associated with GBS. My mother had symptoms of paralysis or lost total function of her legs & arms after having the flu shot. No longer able to stand or walk. Is totally bedridden now. Tried therapy but the recovery time is slow. Didn’t understand what happened to her until we realized the same exact thing happened to her last year right after the flu vaccine. Last year her Dr. wrote it off as lack of use of her legs & arms. Said it was normal to lose function when a person is sedentary. I didn’t understand how someone could walk 1 day & not the next. My Dr. told me that elderly people or people over 65 get a Super Flu Shot that is Triple of what the normal is. He said sometimes that can be to strong for some elderly people to take. That is just crazy!

  4. My brother GBS shortly after receiving the flu shot in late Oct. 2014. It took the hospital 4 1/2 weeks to diagnois him with GBS, after repeated requests by family members to test him for GBS. He became paralyzed from the neck down by this time. There was one other young women in her 30,s diagnosed with GBS shortly after my brother was diagnosed, in the same hospital. RARE I THINK NOT. Thank god they finally listened and started him on treated (there is a 6 week window in which to start treatment,for the best recovery) and that,s not always a guarantee. Prior to the hospital diagnosis of GBS, they preformed an Ablation on his heart to regulate his rhythm as it was all over the place. Irregular pulse and blood pressure is one of the symptoms of GBS. DUH …clinical text book case for whatever reason they wanted to ignore. Soooo important to advocate for your self or loved ones. This was a prestigious hospital in PA…..so what does that say? I’m very happy to report he is now in acute rehab and already gaining his function back, to what degree remains to be seen. We are keeping positive and anthusiatic for a complete recovery. My Christmas Wish has been answered.

  5. It’s time for a bit of clear thinking on the flu shot/GBS debate. My father-in-law died from GBS a few weeks after a flu shot. He had been in good health, and had not had flu for years. He was 77, and his GP persuaded him that contracting flu at his age could be dangerous, so he should have annual flu shots.

    After his death, my instincts kept telling me that flu shots can lead to GBS, so stay away from them. On the other hand, scientists subsequently conducted some extensive studies on GBS triggers and announced that flu could also be a GBS trigger. They generally concluded that there was little difference in the risk of getting GBS from a flu shot or from flu itself. However, because flu can cause death in several other ways, they concluded that we would all be better off with the annual flu shots.

    Well, would we? I am now 77, and many GPs currently encourage patients over the age of 60 to have annual flu shots. I have not had flu in the past 17 years. If I’d had annual flu shots since age 60, I would probably still not have caught flu, but I would have had 17 additional opportunities to contract GBS (from flu shots) in that time.

    Sorry, Doc. No flu shots for me. I think I’d prefer to take my chances with the flu.

  6. I had gastro in late August 2012…which continued for 2 weeks. During this time I started to feel numbness and pins and needles in my hands and feet….which slowly spread as far as my abdomen. I also had excruciating lower back pain. I was going to the Drs every 2 days and they were just passing it off and giving me anti nausea injections I ended up so sick and dehydrated I could’nt walk or even pee. I was hospitalized, put on a drip, catheterised and had regular morphine injections for the pain. 5 days later a specialist saw me and immediately diagnosed GBS. I was treated with plasma but unlucky for me it didn’t cure it, just eased somewhat. I still have numbness and tingling and days where I just can’t get my legs to work for me. I can’t help but wonder if I was diagnosed as soon as I told Drs of my symptoms if I would be better. Even tho I will have this for life at least I am alive. Hard to believe a bout of gastro could cause this

  7. Hi I had a flu jab in September 2014
    I am having problems with my left arm I have lost muscle of my arm it feels week can’t lift things as before still suffering with twitching. Drs do not want to admit any thing I just read these articles and realised what I have gbs
    Is there any one pleas who can advise me what I can do to cure as drs should warn patients about this that how it can effect your nerve system so then patients can make decisions.

    • You need more information. It is wise not to jump to conclusions at this stage. However, you are absolutely correct to ask the question about possible GBS.. As a matter of urgency, you should seek a referral to a specialist who can determine what your symptoms mean. It is urgent because GBS can fairly quickly become life-threatening. If you were to lose the ability to breathe (even temporarily) you need to be in a situation where they can keep you alive. I lost a family member because that support was not provided in time.

      Your symptoms may well turn out to be unrelated to GBS, but you must insist on a proper daiagnosis as soon as possible. Even GBS is not a death sentence, and many GBS victims ride out the storm and make a pretty good recovery. Good luck with your diagnosis.

  8. On Dec 12 2012 I was walking through A Kaiser entry and was confronted with free flu shots. believing then and now it is a pink elephant phenomenon I thought “what could it hurt” on February 8 2013 I knew the answer to that question. that morning my legs were difficult to move by the 10th I could not walk. after two visits to uninformed doctors in Kaiser emergency I had the good fortune to have my personal doc see me on Friday morning and by that evening I was in IC beginning treatment. the relationship between flu shots and GBS is somewhat anecdotal but I am not about to wait for the facts. The FACTS on flu shots and the flu do not appear to have anything closer in the way of undisputable results, rather they appear to have a serious helping of fiction. A completely controlled experiment on shots and flu could not have been done as the strains change every year. So what are we really buying here and at whose expense. Sorry Doc you just don’t have the kind of documentation that make me comfortable. It would be good to find more about GBS before we really understand cause and effect and how GBS is impacted by flu shots..

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