One of the arguments made by vaccine denialists is that vaccines cause significant increases in nervous disorders, and they point to the vaccine’s Package Insert (PI) as “proof”. Setting aside the misuse of the information in a PI, there seemed to be some evidence that there was a slight increase in the rates of Guillain-Barré syndrome (GBS) following vaccinations, although the risk was far outweighed by the benefit of preventing deadly diseases. Guillain-Barré syndrome is an autoimmune disorder of the peripheral nervous system, where the immune system appears to attack nerves involved in movement, although sometimes it attacks respiration and other functions. Guillain-Barré syndrome is usually preceded by a viral or bacterial infection, such as the flu. It is a serious condition, which often takes several months for full recovery. About 80% of those who contract the disorder recover fully with treatment.
Recently, in a meta-analysis published about the risk of GBS after receiving the H1N1 influenza vaccine, it was determined that there were approximately 1.6 additional cases of GBS for every 1 million doses of H1N1 vaccine. This is an extremely small increase in risk, especially compared to the risk of hospitalization and death from H1N1 influenza itself. In fact, the death rate from H1N1 is approximately 200 out of every million H1N1 infected individuals. It’s a no-brainer as they say.
However, GBS is so rare, a huge number of patients need to be included in a study to determine statistical significance of the results. In a recent article about GBS and vaccines, the researchers decided to examine the medical records of one of the most comprehensive and modern health care plans in the world, Kaiser-Permanente (K-P). They own the medical offices, specialists and hospitals, rather than contracting it out, so every patient’s medical record is centralized in one location, and, for ease-of-review, it is all computerized. The researchers examined nearly 33 million person-years of medical records, a number that reflects both the number of people tracked and how long they were followed. For example, 3.3 million people tracked for 10 years would represent 33 million person-years. Out of that 33 million person years, the researchers found a mere 415 GBS cases.
Out of those 415 cases, the researchers determined the following:
- Approximately, two-thirds had a documented gastrointestinal or respiratory infection in the weeks before developing GBS.
- Only 25 of those individuals had received a vaccine of any kind within six weeks of the onset of GBS. Eighteen had flu shots, two got pneumonia vaccines, three had tetanus shots and three got hepatitis vaccines.
The authors could find no statistically significant increase in the risk of GBS with any of those vaccines. In fact, they actually showed that those who received the pneumonia vaccine actually had a lower risk of GBS (though not statistically significant). In other words, the only causal link for GBS from this study is getting sick from a gastrointestinal or respiratory infection. The 25 individuals who got GBS in the period of time after getting a vaccination is no different than the recognized background rate of GBS. In other words, irrespective of the vaccination, they contracted GBS.
The authors concluded that, “In this large retrospective study, we did not find evidence of an increased risk of GBS following vaccinations of any kind, including influenza vaccination.”
There are some weaknesses to the study. It self-selects for individuals who are in a better health care system, so some confounding variable (like the quality of health care itself), reduces the chance of GBS. Because the study only includes Kaiser’s Northern California region, there might be some confounding variable, like better weather, that reduces the risk of GBS. However, given the fact that the researchers was examining all patients, and a huge number of patients, comparing the background rate to vaccine linked rate, and finding no increased risk, the results strongly suggest that there is absolutely no link between Guillain-Barré Syndrome and vaccines.
- Baxter R, Bakshi N, Fireman B, Lewis E, Ray P, Vellozzi C, Klein NP. Lack of Association of Guillain-Barre Syndrome with Vaccinations. Clin Infect Dis. 2013 Apr 11. [Epub ahead of print] PubMed PMID: 23580737.
- Salmon DA, Proschan M, Forshee R, Gargiullo P, Bleser W, Burwen DR, Cunningham F, Garman P, Greene SK, Lee GM, Vellozi C, Yih WK, Gellen B, Lurie N, H1N1 GBS Meta-Analysis Working Group. Association between Guillain-Barré syndrome and influenza A (H1N1) 2009 monovalent inactivated vaccines in the USA: a meta-analysis. The Lancet. 2013 March 13;. DOI: 10.1016/S0140-6736(12)62189-8. PubMed PMID:.